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1. Figure 192b A TYPICAL SCHEMATIC WIRING DIAGRAM OF AWINDOW WALL MOUNT AIR CONDITIONER Compressor 330 Figure 193 imide Unit TYPICAL COMMERCIAL OR RESIDENTIAL CENTRAL AIR CONDITIONING SYSTEM Bises iini meum re rmm maaan prm Indoot Thermoktat See Pages 225 115 vac and 710 VAD through 227 Figure 193 shows a wiring diagram of a typical commercial or residential central air conditioning system You can see that there are two power sources 220 VAC coming directly from the circuit breaker box next to the condensing unit outside the structure and 115 VAC which would come from a wall outlet to power the fan relay inside the plenum chamber The low voltage created by the step down transformer goes through the indoor wall thermostat to energize the contactor inside the condensing unit see p 244 When the contactor coil is energized it creates a magnetic field and overcomes the spring pressure which draws down the armature causing the points to connect T and T with L and L Since the 230 line voltage is also connected to L and L the 220 VAC circuit to energize the compressor and the condenser fan motor s is created The circuit will remain in this state until the wall thermostat is satisfied and disconnects the low voltage from the contactor At this time the coil loses its magnetic field and spring pressure takes over to return
2. 17 18 19 20 CAUSES OF HIGH SUPERHEAT Flash gas Liquid line restriction Improper piping design Inadequate subcooling Low head pressure Capillary tube or TEV distributor restricted Excessive load on the evaporator above design conditions System contamination Results of using an undersized TEV Using an internally equalized TEV Gas charged TEV Sensing bulb failure or loss of charge Results of using the wrong thermostatic charge Measuring and adjusting operating superheat Oversized evaporator or undersized compressor Superheat adjustment too high CAUSES OF LOW SUPERHEAT Overcharge of refrigerant and or oil Compressor oversized Uneven or inadequate evaporator loading Excessive accumulation of oil in evaporator Poor bulb and equalizer location External equalizer line plugged or crimped Cracked diaphragm or bellows automatic expansion valves System contamination Evaporator fan blade on backward motor running backward Oversized condenser Excessive subcooling Poor distribution through evaporator circuits Faulty TEV or wrong charge in sensing bulb Interrupted pump down Oversized TEV Cold suction line or compressor location encourages liquid migration to the low side during the off cycle TEV seat leaks or liquid line solenoid seat leaks or the compressor discharge valve leaks during the off cycle Excessive coil frosting A long free
3. 3 Good Tools Are Half th 5 Basic 1 vais acca cncstiawias 7 Residential Refrigerators and 13 The Brazing and Flaring Methods of Connecting Tubing 37 Testing Residential and Commercial Refrigeration Units 47 Procedures for the Evacuation and Charging of Commercial and Residential Refrigeration 107 Additional Controls for Commercial Units and Compressor Service VaIVOS cccccccccccccccceccsssessessessesaeeeeeeeeess 131 sms 185 Water Coolers and Fountains Sob auae 203 Refrigerated Display Cases and Walk In Coolers 209 Repair Techniques in Commercial and Residential Air Conditioning 5 225 Basic 289 Troubleshooting Refrigerant Flow Controls 357 Checking Out the Solid State TEV Thermal Electric Valve 383 Servicing a Cooling Water Tower 393 Substituting SUVA Refrigerants for CFCS 399 Glossary OF MENM Saesaare de 419 ACKNOWLEDGMENT The author and AIR ZONE Re
4. ul coronam cece dor the tmu diaji mal eng ee hj pe cmm anms ipit be oord on rp cd Pen coder ii ee bth ie ni rds Fu jima duas ced deter dus reed Ex den 08 according ten rehia ath a Sembee arn IE CT ee cooker mamie of the bathing Tus Ganra kx imi peer be her uxeardi tp of corer 1 remporwim the mi il ul teebignation comin MET SS ee t Eh s ams i 212 In many commercial refrigeration units that produce low temperatures such as frozen yogurt machines etc the condenser is required to cool more rapidly than what can be accomplished by just circulating air through it In these units the heat from the condenser is absorbed and dissipated much faster by circulating cool water over or adjacent to the condenser coil Circulating water picks up the heat from the condenser coil and then pumped into a cooling tower usually located on the roof of the building where a fan s draws air in through cooling fins or slats over which the water is sprayed See fig 87 All of these actions cause the heated water to cool far more rapidly than any one of them alone The cooled water is then drawn from t
5. Meutral a Drar Terminals 1 and 3 connected to the timer motor Terminals 2 and 3 connected to the timer moto Terminals 2 and 4 connected to the timer motpr Figure 541 80 A good way to find out if the timer motor fails to change cycles is by visual observation Watch the timer dial while it is connected to the power for a short time If the timer dial turns there is nothing wrong with the timer motor Some commercial type timers are equipped with a sensing bulb which is attached to the evaporator coil When enough ice accumulates on the evaporator coil the sensing bulb transmits the changes in temperature to the timer bellows and causes the timer to take the unit into the defrost cycle by stopping the compressor motor the evaporator fan s and energizing the evaporator heater or the hot gas solenoid Then when sensing a rise in evaporator temperature power is restored and the unit restarts The defrost period on these timers can be regulated by turning an adjusting knob inside the unit cabinet to lengthen or shorten the defrost period Some large commercial units with multiple evaporators use more than one timer TESTING OVERLOAD PROTECTORS If the unit does not run or if it short cycles it can be due to a dead or weak overload protector An overload protector is mounted on the compressor under the plastic compressor terminal cover It prevents the compressor from overheating by opening th
6. 21329 3 puejado se31no 393 394 HOW TO TRACE WATER CIRCUIT TROUBLES To pinpoint the source of a blockage disconnect one by Figure sto one the water inlet and outlet nar gii M m y hr connectedtoeachcomponentand i M mirochiorie Bal ion see where the water flow stops 1 Disconnect the water outlet hose from the condenser to see if the water flows up to CAUTION Use that point water protective 2 If not reseal the connection loves and goggles and disconnect the condenser water inlet hose to see if A EL 9 water flows up to that point If 3 10 water flows to the condenser bucem inlet but does not flow out heel Weca of the condenser or if it flows OMOAEEEES Connection too slowly the problem is a restricted condenser caused bythe formation of deposits on the inside of the tubing walls One way to clean a water cooling tube is to Use containers made of acid connect a vent pipe to the upper condenser resistant material Never use connector and pour the dilute hydrochloric acid aluminum or galvanized vessels solution through a funnel as shown Either the water cooled condenser is replaced or the water lines within the condenser must be cleaned with a power driven wire brush after removing the condenser end plates or by using a dilute hydrochloric acid solutio
7. From Cr ecr f pei li li TIBI ci Li T cz Li To Cmmpregsger Suction 5 Figure 103b Courtesy of ALCO Controls AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 157 REVERSING VALVE When this solenoid valve is de energized the unit is in the heating cycle which means that the indoor coil acts as a condenser and the outside coil acts as an evaporator See fig 103a The discharge gas flows through ex gh EI ports D and C2 making the indoor T L coil the condenser Thermostat z vein in IR Figures 156 Transformer Compress sed A typical heat pump circuit using a 24 volt contactor coil reversing valve and thermostat The suction gas flows from the outdoor coil evaporator through reversing ports C1 to S and back to the compressor When the coil is energized see fig 103b the unit changes over to the cooling cycle with the discharge gas flowing through reversing valve ports D to C1 making the outdoor coil the condenser and the suction gas flows through port C2 to S thus making the indoor coil the evaporator Figure 105a shows a typical wiring of a reversing valve in a heat pump that uses line voltage Figure 105b shows a typical heat pump circuit using a 24 V contactor reversing valve and thermostat A typical heat pump circuit using a line voltage contactor coil reversing valve and thermostat d a E E u E i HEATIMG CREE n
8. H irai ee ira besar iii n Baton LA eee ICE MACHINES This section covers the operation of various types of ice machines It includes an easy to follow diagnostic chart and provides an electrical diagram of a typical ice machine Courtesy mi iWilstire Corp hembu Mirai 185 186 ICE MACHINES Primarily ice machines are nothing more than simple refrigeration units with a few differences Only water and refrigeration are involved with a well insulated but unrefrigerated bin to store the ice chunks or flakes In the cube producing units water enters a reservoir tank It is then circulated by a water pump and then sprayed onto the extremely cold surface of the mold evaporator where a thin layer is frozen almost instantly see fig 128 Excess water is circulated back into the reservoir and the process is repeated One thin layer forms at a time until the molds are filled A thermostat See fig 130a is installed close to the molds when the ice formed in the molds become thick enough to touch the thermostat power to the compressor is interrupted and the circuit to a heating elementis closed to loosen the ice from the molds causing the cubes to fall into the storage bin see fig 128 This cycle is referred to as the harvest cycle In the harvest cycle of units that use a hot gas defrost system the compressor is not stopped Instead a solenoid valve opens and allows the hot gas from the compress
9. 10 9 The side of the compressor connected to the condenser is referred to asthe side 9 10 What component de energizes the compressor upon reaching the desired cabinet temperature p 10 What causes the unit to start running again after a compressor shut off p 10 Why can refrigerant R 134A not be kept in an open container p 7 When turning a nut or bolt how should force be applied to the wrench p 5 Why is caution advised when handling refrigerant pp 3 4 What is the purpose of an accumulator p 9 Under normal operating conditions what is the state of refrigerant flowing through the filter drier p 9 Why should transporting a refrigerator on its back be avoided p 4 What should be done before removing a capacitor p 3 Where is the filter drier located figs 1 2 How are a refrigerator an ice machine an air conditioner and a freezer alike p 8 RESIDENTIAL REFRIGERATORS AND FREEZERS This section explains how residential refrigeration units work It illustrates and describes the function of the various components used in these refrigerators and freezers It includes manual defrost cycle defrost and automatic defrost units Courtesy of Marvel Industries Division of Northland Corporation 13 14 THE BASIC REFRIGERATOR The sealed system consists of a compressor evaporator condenser tubing filter drier and an accumulator The illustration below is a rear view of a
10. Deep ree NI Hen Capacitor Tan Rotor H Thermcatatk a The wall air conditioner with Lo Cool switch energized The thermostat is not satisfied the compressor is running esmpress the fan motor is on Lo Speed ps ium Capacitor Far Sear man Caparites Fan fertur BK Black BL Blue BR Brown C Common OR Orange P Purple W White Y Yellow 324 Hi Fan will engage when unit is on Hi Cool Compre fun Capati tor Fan Bohr fan Star Thewallairconditionerwith Hi Cool switch energized The thermostat is not satisfied the compressor is running and the fan operates on Hi Speed pP Figure 189 Ting Capacitor or Fee Stor i Pur Capa tor n ow The wall air conditioner with Hi Cool switch energized The thermostat is satisfied and only the fan motor is operating on Hi Speed Figure 189d Thermostat closes on heat rise AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 325 Line Ceed Hon Eibbnad Fan Motor around n Capacitor Caparibsr A typical schematic wiring diagram for a wall window air conditioner with overload protector outside of the compressor Figure 190a 31399 UOSJ2UJ3 JO UOISIAIG s498pou e3UM 40 so34n05 Electric heat thermostats 1 and 2 Two pole disconnect type 3 and 4 Single pole type 326 Lins De E
11. Wall TharmcwkrE puo fg 163 pp 352 353 10 11 12 13 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 351 QUESTIONS AND ANSWERS ABOUT THE DIAGRAM ON PAGE 310 Is this a frost free refrigerator Yes because a defrost timer is being used in the wiring On what scale should the ohmmeter be set in order to get the correct ohm reading or continuity in the following The compressor The lowest scale The evaporator or condenser fan motor The lowest scale The capacitor On the highest scale The defrost heater On the lowest scale What voltage reading should be expected between points 0 VAC Is the compressor grounded to the chassis Yes What voltage reading should be obtained between points N O 0 volts Is the unit in a cooling or defrosting cycle Cooling What three components in the compressor circuit control the operation of the compressor The defrost timer thermostat and overload protector In the defrost heater circuit what component controls the operation of the heater The defrost thermostat What controls the operation of the light bulb Y X light switch What components in the entire diagram are grounded four the compressor condenser fan motor evaporator fan motor and the defrost timer Supposing the timer motor has a resistance of 4000 O By placing a flux type ammeter between points M N what ampere reading should be expected to d
12. Gee Fig 157 contre Pasal Wall Mount Thermostat AN A COIL EVAPORATOR INSTALLED IN THE AIR HANDLER Drain pan Condensate drain line Liquid line Suction line Expansion valve 252 jo Steer An automatic vent damper reduces heat loss by closing the vent between heating cycles This energy saving device can be used in new or Figure 161 existing systems This drawing illustrates a typical heating air conditioning duct work mounted in the ceiling or floor of a home or office building Also known as a perimeter loop system it carries the conditioned air from the furnace and evaporator housing to each room or office through this duct work dust and dirt particles are trapped before reaching the evaporator These filters should be replaced at least once a month or cleaned that often if they are of the permanent type When this is not done on a regular basis the dust and dirt particles clog the filter restricting the air passage In this case the evaporator fails to get sufficient air circulation Ice builds up on the coil causing a further restriction and the unit fails to cool Condensate water will not drip into the pan under the evaporator coil because of ice blockage causing the moisture to flow outside and run onto the floor The same symptoms occur when sludge and dirt accumulate inside the drain pan or the drainpipe causing the water to overflow in the pan and wet the floor In a
13. modal fic OCTH bisp cap f rimy x 72 A D Super Tap Raiden bla Needle specially 5 E Model No QT 100 engineered tip provides three times the flow 1 Insta Tap Refrigerant Recovery Tool Snaps onto refrigerant line and punctures a large hole for maximum flow to recovery unit 2 and 3 Wagner Line Piercing Valves They are available in 1 4 5 16 3 8 1 2 and 5 8 to fit those tubing sizes Courtesy of Wagner Products Corporation Miami Florida 414 SUVA VAPOR PRESSURE TEMPERATURE RELATIONSHIP CHART TEMP HCFC HCFC HFC HFC TEMP HCFC HCFC HFC HFC F 123 124 125 134a T 123 124 125 134a 100 29 9 29 2 24 4 27 8 90 29 8 28 8 21 7 26 9 110 10 5 79 7 291 6 146 8 80 29 7 28 2 18 1 25 6 120 15 4 94 9 334 3 171 9 70 29 6 27 4 13 3 23 8 130 21 0 111 7 380 3 199 8 60 29 5 26 3 7 1 21 5 140 27 3 130 4 430 2 230 5 50 29 2 24 8 0 3 18 5 150 34 5 151 0 482 1 264 4 40 28 9 22 8 49 14 7 160 42 5 173 6 301 5 30 28 5 20 2 10 6 9 8 170 51 5 198 4 342 0 20 27 8 16 9 17 4 3 8 180 61 4 225 6 385 9 10 27 0 12 7 25 6 1 8 190 72 5 255 1 433 6 0 26 0 7 6 35 1 6 3 200 84 7 287 3 485 0 10 24 7 1 4 46 3 11 6 210 98 1 322 1 540 3 20 23 0 3 0 59 2 18 0 220 112 8 359 9 30 20 8 75 74 1 25 6 230 128 9 400 6 40 18 2 12 7 91 2 34 5 240 146 3 444 5 50 15 0 18 8 110 6 44 9 250 165 3 491 8 60 112 25 9 132 8 56 9 26
14. AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 75 Testing Procedure 1 Disconnect power to the unit 2 Disconnect the relay from the compressor by pulling it off the compressor terminals or by pulling off the wires connecting it to the compressor run and start terminals In most commercial units the relay is not directly attached to the compressor terminals instead it is installed in a control box next to the capacitor near the compressor and wired to the compressor terminals 3 Disconnect the only power line to the relay and connect it directly to the compressor run terminal 4 Using a length of wire with alligator clips at each end and a momentary contact switch in the middle connect the compressor R and S terminals The wire should be twelve gauge or heavier 5 Reconnect power to the unit and depress the switch for no longer than three seconds and release it If the compressor starts and remains running the relay must be replaced See figs 50 and 51 Also see Testing the Compressor with a Test Cord ll TESTING A POTENTIAL TYPE RELAY Potential relays are wired to all three compressor terminals and not just to the compressor run and start terminals When a compressor motor fails to operate and the potential relay is suspected to be the cause the best way to test it is to use a compressor test cord See fig 35 36 Start the compressor by bypassing the relay If the compressor starts running the starting r
15. Check compressor terminals with ohmmeter replace if necessary Disconnect discharge and check Check and replace if necessary Try switching to another circuit or call electrician Check pressure and shut off valve Test and replace if necessary Check wiring with schematic diagram Make sure line voltage is not over 10 above compressor rating if so call electrician to correct it 1 High voltage or excessive running time Start Capacitor Burnout 1 Sticking relay contacts 1 Clean contacts or replace relay 220 Problem and Possible Cause 2 Wrong capacitor 3 Unit short cycles 4 Runs too long on start winding Relay Malfunction or Burnout 1 Relay vibrates Unit short cycles Wrong relay Relay mounting or connections wrong Wrong run capacitor Line voltage too low Line voltage too high Remedy Verify correct capacitor rating Reduce cycling frequency by in increasing the differential on the pressure control or change capacitor Check for low voltage or reduce frequent starting by regulating valve installed on suction line in multiple evaporator system Secure mounts or move relay to a less shaky location Reduce cycling frequency See 3 above Install a relay compatible with compressor motor specifications Install relay correctly and check for proper connections Install proper capacitor Voltage cannot be more than 1096 lower than motor rating Voltage cann
16. 19 20 21 22 23 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 347 step electrical operation in the circuit 24 VAC power flows in the circuit through the HEAT switch TH 1 RVR then back to the other side of the line With the RVR contact at the bottom of the diagram closed power flows through the circuit to the other side of the line energizing the CR coil relay A 24 VAC also flows through the IFR internal fan relay and to the other side of the line With the CR IFR and the RVR reversing valve relay energized the contacts within the relays will become activated and the 230 VAC circuitry will close the RVS OFM IFM and C causing the reversing valve outside fan motor inside fan motor and the compressor to become energized and commence operating The CH will become de energized Can the heater relay HR 1 second stage supplemental heat become energized without the compressor operating No What purpose does a defrost thermostat DFT serve By sensing the temperature on the outside coil it initiates or terminates the defrosting How and when is the defrost cycle started It is automatically started every ninety minutes by the defrost timer How doesthe compressor start When the inside thermostat IT or the TH 1 is closed the heat or cool switch is closed and when the contactor relay CR is energized What are the two ways the unit is taken out of the defrost cycle The defrost timer
17. 5 6 Disconnect every wire from the thermostat Set the ohm meter on the RX1 scale and turn the thermostat to its warmest setting While holding the thermostat bulb in your hand for about 2 minutes touch the two ohm meter probes to the two thermostat terminals You should get a 0 reading on the meter If not the thermostat is bad and should be replaced Turn the thermostat to the off position and touch the probes again to the two terminals You should get an open circuit reading If not the thermostat must be replaced Turn the thermostat to its mid position and put the thermostat bulb in a mixture of crushed ice and a little water for about 3 minutes while touching the ohm meter probes to the two thermostat terminals The indicator needle should move from to an open circuit reading If not the thermostat must be replaced REPLACING THERMOSTATS Thermostats used in residential units are installed in the fresh food or freezer compartment while the sensing bulb is attached to the evaporator coil There are occasions when the sensing bulb is routed through a maze of holes in the cabinet making it appear impossible to replace once the original one is removed There is a way to make this job much easier When all the screws securing the defective thermostat sensing bulb and or sensing bulb line are removed tie a piece of strong cord a few feet longer than the sensing bulb line securely to the sensing bulb Pull out the old thermost
18. Connect the high pressure gauge to the service valve and compare the reading with the pressure calculated from the chart If the reading exceeds the expected pressure by more than 5 psi shut down the unit The problem may be due either to the presence of air in the system or the system being overcharged Open the gauge connected to the discharge service valve and purge the system for about twenty seconds Turn on the compressor again Purge the system for another twenty seconds and watch the gauge A head pressure drop even a small one is an indication of air in the system If there is no pressure drop the problem can be due to an overcharged system Resume purging until the last condenser coil and the bottom of the liquid receiver feel cold to the touch Another common water cooled condenser problem is the settlement of waterborne impurities on the tubing walls This is easily identified by the higher than normal head pressures and a hot liquid line provided of course there is no air in the system and it is not overcharged The most common means of controlling waterborne deposits is through the addition of a weak sulfuric acid chromate solution to the water in the cooling towers Commercially prepared scale prevention chemicals are the safest cleaners These can be purchased from refrigeration dealers Follow the directions carefully 396 TYPICAL COMMERCIAL REFRIGERATION SYSTEM USING A PARALLEL COMPRESSOR ARRANGEMENT Court
19. Failure of Flooded Head Pressure Control System No Bypass Foreign material wedged between condenser a Artificially raise head pressure and tap the valve port and seat body to dislodge foreign material Wrong pressure dome on valve for system Change dome or valve Hot gas bypass line restricted or shut off Clear obstruction Sensing bulb lost its charge Change the valve Oversized condenser or condensing unit Replace with properly sized condenser Pressure of condenser bypass regulator Adjust condenser bypass regulator setting to OPR set too low appropriate level Normally set 20 psi below condenser pressure regulator IPR setting AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 377 11 3 Fluctuating Discharge Pressure Probable Cause Faulty condensing water regulating valve Insufficient charge usually accompanied by corresponding fluctuation in suction pressure Inadequate and fluctuating supply of cooling water to condenser Cooling fan for condenser cycling Fluctuating discharge pressure controls on low ambient air cooled condenser Fan cycling caused by pressure switches Applies to water cooled condensers Remedy Replace condensing water regulating valve Add charge to the system Check water regulating valve and repair or replace if defective Check water circuit for restrictions Find cause and correct Adjust repair or replace controls Normal for fan cycling operati
20. Reduction Elbows and Tees 5 16 3 8 4 W W Figure 24b Elbow One end 7 Pipe x Elbow x x Tee Both ends same size x Figure 24a HOW TO MAKE A FLARED CONNECTION 1 Cut and clean the ends of the tubes as described earlier Use a fine toothed file to smooth the ends or to make a slight correction if the tubing is not cut perfectly square 2 Place a female flare nut on each of the tubes with the larger end facing the cuts Do this prior to making the flare because the nut will not slide over the end after the flare is made 42 3 Figure 25a Slide the nuts back on the tubes to provide enough working room Then put the end of the first tube into the flaring block hole with the same diameter as the tube The end of the tube should extend slightly above the chamfered end of the hole to allow enough metal to form a satisfactory flare The tools have directions with them for guidance in this step As a rule of thumb the extension above the block should be about one third of the height of the flaring See fig 25a and 26 111 Fiaring Hed get 5r Spinner Lg ERIT Flare 2u sjonpoJd JO A FLARED COUPLING Etainlaes Wire lirzzhamg Figure 25 Put a drop of refrigerant oil on the bottom of the flaring cone where it comes in contact with the tubing Tighten the spinner until the flare is formed Avoid overtightening as this will thin out the wall of the tube and weaken the flare In
21. diagnosed simply by checking the m compressor discharge and suction pressures The recommended TER DRIERS USED high and low side pressures for IN RESIDENTIAL UNITS every model of residential unit Auedwo3 aye 40 AsayinoD 28 manufactured in the United States can be looked up in a reference book called Tech Master published by Master Publications Filter drier A cylinder made of copper or brass of varying sizes depending on the capacity of the unit filled with alumina or silica gel Its function is to remove moisture that penetrates the sealed system by absorption It is installed at the inlet of the capillary tube The ends are either silver brazed or coupled by flare connections Inthe sealed system only pure refrigerant and asmall amount of clean refrigerant oil should be circulated Any moisture penetrating the system will cause a lot of trouble The air in the atmosphere can penetrate the sealed system through very tiny pinhole leaks in the tubing or at the joints Air contains moisture When it enters the system the excessive low temperatures cause the moisture to freeze and block the circulation Hence the reason for the installation of filter driers Since the narrowest passage through which refrigerant moves is the capillary tube this is the most likely place for the restriction When a restriction occurs the unit will no longer cool When a sealed system is opened moisture gets in and the filter drier m
22. 1 0 Either the needle and scale type voltmeter or d E a digital type multimeter E 1 is used to detect faulty components in electrical circuits AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 303 The circuit below shows four positions for voltmeter readings These positions produce the following readings 1 It s 115 to 120 VAC when power is on Zero voltage when power is off No reading if switch is closed or a voltage reading if switch is open 3 Avoltage reading across the resistor with the switch closed No voltage reading across the resistor with the switch open 4 Avoltage reading across the lamp with the switch closed No voltage reading across the lamp with the switch closed if lamp is shorted A voltage reading across the lamp with the switch closed if the lamp is burnt out or inoperative r9 The total voltage across numbers 2 3 and 4 should be equal to the reading across L1 and L2 if the switch at number 2 is closed and power is on 132 120 E Voltage T ul Credit card size multimeter measures volts ohms and amperes A combination volt and ohmmeter with a digital readout is recommended for ease See p 269 of use in lieu of the needle and scale type illustrated above Uone1odjo jeuisnpu uewyoog jo Aseqino 304 UNDERSTANDING ELECTRICAL CIRCUITS Instead of drawing pictures to illustrate the various parts of an electr
23. 1 Disconnect the power Where a split system is used be sure to disconnect power to the furnace air handler as the transformer is energized there Remove the snap off thermostat cover Remove the wires from the base Remove the sub base and the base Run the wires from the wall through the hole in the new sub base and fasten it to the wall If the wall is thin use behind the wall expanding nuts moly bolts being careful not to tighten them too much Very often regular wood screws work as well 6 Run the wires through the base Fasten the base loosely just to hold it in place while connecting the wires to their designated and marked terminals Be sure that each wire is confined within its proper area so that the cover can be mounted properly 7 Adjust the base with a small carpenter s level and tighten the screws Check the level again after tightening the last one If it is not perfectly level loosen the screws and try again Step 7 of course only applies to the mercury bulb thermostats Skip step 7 when installing solid state wall thermostats because they are not sensitive to accurate leveling 8 Finally snap on the cover reconnect the unit to the power supply and start the unit ON pe INS 262 wall openings Run the thermostat wiring to the designated location on the wall and pull about three inches of wire through the hole fig 2 Hang the thermostat on the tabs at
24. Compressor Condenser fiscal ve Compressor Probecior Ewapixabor Preisure Regalater Pid Figure 37e Pressure High Temp Fwapeorater Regulating Valve High 5kfe Pressure Control Low Ambient panai INSTALLATION PRESSURE REGULATING VALVE TO SERVE DIFFERENT PURPOSES 97b A valve installed in the system to protect the compressor against burnouts 97c Valve installed in evaporator suction line to stop evaporator pressures from dropping below a desired minimum 97d A valve installed in the liquid line at the condenser outlet to close at low ambient temperatures 97e A valve installed at the outlet of the warmest Winter Start Control evaporator in a multiple evaporator system It prevents pressure drops below a desired point in the warmest evaporator 97f A valve installed in a bypass line between the compressor and the receiver to quickly admit discharge gas into the receiver at the start of the refrigeration cycle to rapidly build operating receiver pressure The valve closes when operating pressure is reached Courtesy of Eaton Corporation Controls Division 148 Figure 97c shows pressure reducing valve installed in the evaporator suction line to prevent evaporator pressures from dropping below a desired minimum Installation of these valves on the suction line for example can prevent liquid in chillers from freezing SOLEN
25. Diii CLE a Figure h a haai pp la te coding recie aad Bgas iD ahaa pear ini Pee heating cercle Bey che amenriaa ro bes Grecian of the reiner horas Chine agi hee lass reser be in Pac horde 158 REFRIGERANT CONTROLS USED IN COMMERCIAL REFRIGERATION In residential units a capillary Figure 106 tube connects the liquid line to the evaporator inlet to maintain a pressure difference between the low and high side of the system and also to control the amount of refrigerant flowing into the evaporator In commercial refrigeration the capillary tube is used to some extent but the following controls are also used 1 Thermostatic expansion valve TEV a Bulb type fig 106 b Thermoelectric type solid state also called an electric valve fig 107 2 Automatic expansion valve AEV fig 108 Low side float system fig 109 4 High side float system fig 110 po BULB TYPE THERMOSTATIC EXPANSION VALVE TEV It is installed on the inlet of the evaporator with a sensing bulb connected to the valve body by a capillary tube and mounted on the evaporator outlet See figs 110a through 110e The thermal bulb is filled with refrigerant As the evaporator temperature rises the refrigerant in the bulb attached to the evaporator coil expands exerting pressure on Thermoelectric Valve the diaphragm within the valve Solid State allowing the refrigerant to flow As Figure 107a Courtesy of Eaton Corpora
26. E wn Power E J Figure 74a Figure 74 L Anerdnarg cae puerile s band ar bos aid pect the leveling legs 2 Pauke Tables vehe mesing Using a pocket size digital multimeter to check wall mounted units the continuity of a power cord Finor covers piobert Tones ane help wtih Lave al Poem s Dba Ee um a i 2 Setthe ohmmeter on its lowest scale and zero it 3 Hold the ohmmeter probes on each end of each wire in the cord The meter should register a zero reading in each case If not it will mean that there is a break in one of the inner wires and the cord will have to be replaced 4 f you are using a digital multimeter simply set the meter on its ohm setting to read the amount of resistance Or set it on Continuity touch AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 103 the two sides of each individual line as indicated in figure 74 If there is no break in the line being tested you will hear a light buzzing sound TIPS ON INSTALLING REFRIGERATORS AND FREEZERS When transporting a refrigerator never lay it on its side or back because the compressor oil leaves the compressor Then when in place and turned on the compressor operates without lubrication and it ends up having to be replaced If for any reason it must be laid down for five minutes or longer be sure it is in an upright position for a minimum of twelve hours before being turned on This will allow su
27. Low refrigerant flow See section I high superheat Low airflow through evaporator Low outside temperature on air cooled condenser Evaporator discharge air recirculating Liquid line solenoid leaking during the off cycle Undercharged system TEV problems Remedy See section IV 1 Unload compressors when starting Use interval unloaders if present See section 11 1 Check for mechanical damage check motor and compressor bearings for temperature lubricate motor bearings Determine reason and correct Find source and correct Rewire correctly Replace faulty equipment Replace overload protector if internal replace compressor Replace compressor and install new filter drier s as previously instructed Remedy Find source of problem and take corrective action b Find source of problem and take corrective action 380 c Uninsulated receiver exposed tolow ambient c Insulate or artificially heat receiver air V 3 Unit Runs Continuously Adequately Sized Inadequate Cooling Probable Cause Remedy Load too high Has there been a recent Choose a condensing unit with increased addition to the design load product people capacity to match load requirement or reduce equipment etc load b Low refrigerant charge b Repair leak and recharge Probable Cause Remedy Low refrigerant flow due to liquid line Check and repair liquid feed problem restrictions See sec 1 1 to I 3 Evaporator
28. This section covers the most practical methods and techniques of connecting tubing It includes flaring brazing swaging bending and cutting tubing 37 38 THE BRAZING AND FLARING METHODS OF CONNECTING TUBING There are two common methods of connecting tubing silver brazing or silver soldering or just brazing and flaring Silver brazing Brazed joints are very strong and considered to be the best method of making Figure 17 leakproof connections The correct procedure is as follows CAUTION Before any brazing is begun all of the refrigerant must be evacuated from the system as instructed in the section on repairing leaks in the sealed system 1 Clean and burnish the joints with fine sandpaper The parts to be brazed must be fitted snugly and accurately clean and securely supported so that no part can move during brazing 2 Apply the recommended flux fig 19 for the alloy being used to the outside of the joint after the tubes are fitted snugly together Be sure the joint is firmly supported to avoid movement during brazing or cooling 3 Heat the joint evenly with a torch figs 20 and Use either style 21 using a figure 8 motion More heat will be hacksaw to cut needed for larger tubing Acetylene oxygen tubing tanks along with the appropriate lines and tips can create more heat The kit is available at refrigeration supply houses Start heating about one half inch to one inch away from the joint Never ho
29. To PAC HAG 2 5 escent Tress former A TYPICAL SCHEMATIC WIRING DIAGRAM OF A THREE PHASE CENTRAL AIR CONDITIONER Upper General Diagram Lower Detailed Diagram Bupply L1 gue To FAC MINAC Trazadnurmer To Y of aes F Tharmartat i High Pressures Switch nn pn ondanR E Fan motor Comdensar Fan CapaciL r i bi Solid state Crmnkcamu Heiter Low valt Wirteg Lima Volt Wiring a 342 QUESTIONS AND ANSWERS CONCERNING THE SCHEMATIC WIRING DIAGRAM ON PAGE 341 What color wires activate the contactor coil Yellow Which contactor terminals are connected to the fan motor T1 and T3 Which contactor terminals are connected to the compressor T1 T2 and T3 Which contacts in the contactor are connected to the power supply lines L1 L2 and L3 If the compressor runs but the condenser fan motor does not which components should be checked as most likely to cause this problem Fan motor fan capacitor fan wires connected to contactor terminals T1 and T3 must have a good connection If a fuse blows in the power supply line to contactor terminal L2 what effect will it have on the operation of the unit The condenser fan motor will run but the compressor will fail to start Why will the system become inoperative if the high pressure switch cuts off the low voltage power Because the low voltage power will not activate the contactor coil to connect the line voltage When is the
30. Tranasmissi n ar Wns Corporgnos oan iru AEV adjustment screw counterclockwise to move the frost line toward the evaporator See fig 131a 194 TMAM MS ON AMD IVAPORATOE ASSEMBLY Description Gear motor and cable Shaft goal mount O ring Seah aal Lower waster Lowe Emari dive pe Lock washer 1 4 split amp crww 1 4 s 20 8 3 HHA Funpnrubzr cup Estrodirg head Dovartar beating eut assembos Thama asparisxin vals bracket end adapte eenuntng plate Som Fels LE Gm Po a AUGER AND EXTRUDING HEAD REMOVAL Disconnect unit from power supply Remove storage container cover and put aside Turn off water supply to ice maker After ice has melted from head take hold of the auger nut and lift straight up to disengage from ice maker When replacing the auger assembly make certain that both the auger engages the drive pin and the extruding head ribs engage the evaporator tube see figs 131d and 131e Figure 131e BES Bret ab em Rih 1 Planes Figure 131d Courtesy of Wilshire Corporation Schaumburg Illinois AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 195 INSTALLATION AND SHAFT SEAL REPLACEMENT See fig 131f Hgure 1311 1 0 1 Place shaft seal mount over gear motor output shaft and push down until shaft seal n ing e DE Luba ig rc
31. Variable resistor Relay coil Normally open relay Normally closed relay Line voltage wires Defrost timer symbol used by GE Connector Heating element Overload protector GE Timer Switch Main switch Adjustable thermostat Connected switches Switch Thermostat Closes on heat rise Thermostat Opens on heat rise Thermostat Single pole double throw switch Resistor Thermostat Whirlpool Push button switch Normally closed Push button switch Normally open Two circuit push button switch Multiposition switch AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 307 Transformer Solenoid coil Centrifugal switch Starting relay Power supply grounded Wires connected Light bulb Wires not connected Crossover Terminal Crossover Capacitor Thermister Buzzer Power supply grounded Split phase motor Three speed motor Two speed motor Single speed motor Neon light Fluorescent light Incandescent light Chassis ground Earth ground Low pressure control High pressure control Three speed motor Two speed motor 308 m Evaporator Tan Rater Bg Ohm p Defrost heater t 2 Ohma eh Cold Control L 5 Tharscstat i UR d li Defrost Timer D Bee Cage Heater Aon ITIS wma Energy Saver Switch en Rul line Haater 7100 Chem
32. Water falling in the bin Room temperature too high po ix OO ee Replace solenoid valve coil Check refrigerant pressures repair leak change filter drier and recharge Turn on faucet Replace water float Check and replace if necessary Install new thermostat or recalibrate Unit may be too small for needs Check for inoperative transformer fuse broken wire etc in grid circuit Remove mineral deposits with recommended chemicals Reconnect or turn on Replace bin thermostat Turn switch to On position Replace relay Replace compressor motor Turn master switch on Repair as necessary Relocate unit to warmer area Install new thermostat Recalibrate or replace thermostat Relocate unit to warmer area Replace solenoid valve coil Check and repair sealed system Replace bin thermostat Check water pump water float O and for any restriction in lines a Check water line parts adjust repair or replace b Check water pressure at supply and check water faucets Advise customer AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY Problem and Possible Cause 8 Mineral buildup on evaporator plate Linted condenser Inoperative condenser fan Water continuously fills reservoir and is siphoned off Ice Cubes Come Out Milky Not enough water in water tank Water hardness exceeds fifteen grains Ice Cubes Come Out Too Thin Faulty evaporator thermostat To
33. a o 5 A lt o t ct o 5 Q o E o o a o 3 In side by side units this drain heater can be seen at the bottom of the evaporator around the drain opening Timers are usually mounted directly when the evaporator panel is removed to the back of the units inside the see fig 9 In the case of units with the freezer on top it ison the bottom of the freezer compartment around the drain opening Erretes S ISNPUJ JMEN Jo 2 pUeJYHON JO UOISIAIG AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 25 Different evaporator designs have different defrosting requirements for optimum efficiency Some evaporators must be defrosted every six or eight hours some require defrosting every twelve hours and some in commercial systems are designed to be defrosted is Rue ae anc after every cooling cycle in addition to the USED IN RESIDENTIAL periodic defrosting at regular intervals REFRIGERATION UNITS Timers are usually mounted inside the cabinet next to the cold control or behind the toe plate in the front One of the most common problems leading to timer replacement occurs when the timer motor freezes in one position When it gets stuck in the defrost cycle the refrigeration unit remains in the defrost cycle the compressor no longer runs and the evaporator panel in the freezer compartment feels warm to the t
34. 6 a shorted start capacitor 7 pressure control reaction to a restriction in the sealed system of commercial units 8 the cut in cut out set too close on the pressure control or thermostat 9 a defective compressor 10 loose connections particularly at the compressor terminals 11 an overcharged system 12 an undercharged system particularly one that uses a pressure control 13 extension cord too long and or too light for the electrical requirements of the unit 14 a refrigerant leak in systems using pressure controls and 15 a defective starting relay AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 171 SHORT CYCLING AND A BAD STARTING RELAY If a starting relay does not disconnect the power from the compressor start winding the compressor will keep running on its start winding until it overheats and the overload protector shuts off the power within four seconds Once the compressor cools the contacts within the overload protector close causing the compressor to restart at short intervals If short cycling cycling on overload continues the compressor start winding may overheat and burn If the contacts within the starting relay don t close the start winding will not become energized and the compressor will never start In either case the starting relay will have to be replaced SHORT CYCLING AND PRESSURE CONTROLS A high pressure control is wired in series with the compressor common terminal and it is a
35. And cut out refers to pressure at which the compressor stops operating Not colder than that point NOTE After replacing the low pressure control check the pressures in the unit if it is suspected that any refrigerant has escaped Watch it cycle two or three times after restarting it Remember that pressure controls are affected by the pressures in the sealed system and not by the temperature Use the chart on page 124 to convert any temperature to its corresponding pressure To calculate cut in and cut out do the following 142 1 Using the chart on page 133 determine the evaporator pressure for the warmest allowable temperature Then turn the cut in screw until the needle indicates the correct pressure 2 Determine the lowest allowable evaporator temperature Assume a 20 F drop in evaporator temperature is allowable 3 Find the corresponding pressure for the allowable temperature drop for the refrigerant used in the unit 4 Deduct the allowable pressure drop from the cut in pressure and the result will be the differential adjustment 5 Turn the differential adjustment screw until the indicator is at the proper setting When the pressure in the evaporator drops to the lowest allowable point the cut out switch will automatically turn off the compressor until the low side pressure rises to its preset cut in pressure range EXAMPLE The desired temperature of a walk in cooler using R 12 is about 35 F Determine the cut in and
36. Check for wrong or binding fan or blower wheel or wrong fan motor Check location of sensing element or comfort guard a plastic sleeve missing from sensing element Check compressor for short or ground weak connections broken wires run capacitor overload protector etc Check start capacitor and start relay if unit has these Advise customer unit not designed to operate at low ambient temperature See number 6 above Check thermostat see that temperature is not set too low Check for dirty filter condenser or blower wheel Loose fan or wheel or exhaust door open Check for loss of refrigerant or restriction in sealed system Advise customer to run fan at higher speed check for low voltage Check for binding blower wheel or shaft wrong motor or blower wheel Check for loose parts tubing vibrating against sides or components loose fan blower or mountings Check for worn fan shaft bearing s or loose parts in the unit Could have internal parts worn low on oil or low voltage Correct as necessary Check condition of wiring and connections look for short circuiting and repair as necessary Advise customer to wait two to three minutes before attempting restart Check fuse for proper type and time delay check circuit breaker size for adequate amperage Check power source for voltage no more than 1096 of that on nameplate AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY Problem and Possibl
37. Disconnect the green ground wire and disconnect the individual wires from the timer if there is no connecting block Be sure to mark every Poses 2l war h TIT VM dearer In figures 53 and 53a power is transmitted to terminals 1A 2A 1B 2B 3A 3B 4A and 4B through line 1 line 2 line 3 and line 4 When terminals M and T are connected to the power the timer motor becomes activated and causes the terminals to open and close resulting in making or breaking load circuits energizing or de energizing the load in the circuits at predetermined intervals depending on how it is programmed on the dial The wiring diagram is pasted inside the timer door Figure 54a is the schematic diagram of the electronic timer in figure 54 Power is applied to terminals 1 and 2 At predetermined intervals power flows through terminals 3 and 4 or 3 and 5 not shown on the diagram energizing or de energizing any load connected to these lines AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 77 wire so it may be reconnected correctly Method make a little flag for each wire with masking tape and a fine line marker 5 Set the ohmmeter to the RX1 scale and zero it 6 Connect the ohmmeter probes to the timer terminals 1 and 4 then using a screwdriver coin or putty knife blade turn the cam on the timer clockwise very slowly The meter should register a zero reading until a click is heard At that precise mo
38. Furnace Step down transformer Blower fan Power supply junction Fan relay Filter drier Duct work connection Contactor NEM e NEED Dust Wark zT d E P d wr isaer iry Balay ar Gee vr Electric irq Beet phere A TYPICAL SET UP FOR A RESIDENTIAL OR COMMERCIAL CENTRAL AIR CONDITIONING SYSTEM min CO vec 135 WAG amd 280 RC irasa AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 255 A COMPLETE WIRING METHOD FORA CENTRAL AIR CONDITIONING SYSTEM Unit in Cooling Mode Figure 165 A Typical plenum arrangement It can be either a heat pump or gas fired if gas fittings are installed 4 B A type coil C 1 Suction line opening 2 Liquid line opening 3 Condensate drain Figure 164 Figure 164 A typical plenum chamber Suction line pipe Liquid line Condensate drain line B C and D By removing the screws from the face plate ofthe A coil housing access is gained to the refrigerant control and the condensate drain pan Blower Fan capacitor AIR CONDITIONER WALL THERMOSTATS The thermostat is the temperature sensing part of an air conditioning unit It is mounted on a wall in the air conditioned area and it is sensitive to the changes in the air temperature It turns on or off the relay s and the contactor s responsible for energizing the heating or cooling section of the unit depending on how it is adjusted In th
39. It is wired in series with the electric valve Here the thermistor reacts increasing or decreasing voltage in the valve circuit depending on the state of the refrigerant passing through that part of the line When it is exposed to hot refrigerant gas the thermistor is heated to a high temperature by the voltage applied to it The thermistor resistance drops as it self heats This negative coefficient thermistor causes an increase in voltage to the bimetal heater inside the valve head The amount of low voltage applied to the heater bimetal within the valve controls the degree of valve opening see figs 208 and 209 At zero voltage the valve is closed As voltage is applied the bimetal heater is deflected The needle follows the bimetal deflection and opens the valve The more voltage applied the greater the valve opening 166 Figure 115 There Electric WE e fi Evaporater Lr Frocen food Cass 1 Thmrmiskar dj Il ES Evaporator Bolid ataks T E V Cosprsggcr The installation of an electric valve with a bleed tube When electric valves are used to control multiple Vader FART id evaporators solenoid valves and evaporator pressure regulators are not necessary Terc Voltage The thermistor be installed nearly anywhere the system to perform a variety of functions Depending on where the thermistor is installed the electric valve can control head pressure maximum evaporat
40. Replace gasket check for warped door Check high and low side pressure If head pressure reads too low and back pressure reads too high replace the compressor Check for leaks and charge system if necessary 218 Problem and Possible Cause 5 Restriction in system Refrigeration Unit Is Noisy 1 Compressor mounts loose 2 Vibrating tubing 3 Unit not level or on weak floor Compressor Loses Oil Low Freon oil ratio Oil trapped in lines Refrigerant low Unit short cycles Remedy 5 Check for bent tubing a cold drier blocked or improperly set valves If a pressure increase is created behind a restriction point it will feel warmer or hotter than usual and a pressure drop will feel colder than usual In other words the temperature difference before and beyond a restriction point becomes drastic Check rubber mounts for wear replace adjust or tighten mounts and bolts as necessary Secure tubing with tape wood foam or rubber blocks Residential refrigerators and freezers require leveling every time they are moved or if flooring is uneven 1 pt oil 10 Ibs Freon Keep ratio same if adding to factory charge Position tubing to drain into compressor Check for leaks add refrigerant and oil See other remedies under this title Applies only to those units have water cooled condensers AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 219 ELECTRICAL TROUBLESHOOTING CHART
41. To determine the amperage put a finger over divide the voltage by the resistance For instance there is a need to determine the amperage expected in a particular circuit The circuit is supplied with a 220 volt line and the schematic diagram shows 22 listed under a heater as its resistance Looking at the illustration above the amperage equals the voltage divided by the resistance I E R or 220 divided by 22 equals 10 A If the ammeter reads only 0 5 1 2 A it will mean that there is a short in that particular circuit as there should be a reading of about 10 A EXPECT THE INDUCTIVE REACTANCE IN THE WINDINGS OF A LOAD TO CAUSE THE AMMETER READINGS AND OHM S LAW MATH TO BE SLIGHTLY DIFFERENT The most important law in electricity The current which flows in a circuit is directly proportional to the applied voltage and inversely proportional to the resistance Simply stated when voltage is increased the current increases If the voltage is constant the current changes as the resistance changes but in the opposite direction The more resistance applied the lower the amount of current flow Ohm s law may be easier to understand if a circuit is thought of as a plumbing system With the water valves fully open no resistance the water current is free to flow at whatever pressure electromotive force is applied As one or more valves are partially closed adding resistance to the system the amount of water current
42. Voltage is the energy electromotive force which pushes the electrons through a circuit The passage of electrons past any given point in a circuit is called current Fuse Pat ME pH 27 00 n Circuit TYPICAL CURRENT FLOW TO HOUSE CIRCUITS AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 291 Current is measured by the ampere One ampere is about the amount of current carried by a medium size light bulb Any source of voltage can move electrons such as a car battery a flashlight cell or even a wire passing through the magnetic field of a small handheld magnet although its current is very tiny And that example is an oversimplification of how electricity is created A generator has hundreds of wires in its winding called a rotor with magnets placed around the inside of the housing called a stator to create a magnetic field When the rotor rotates those hundreds of wires pass through that magnetic field hundreds of times per minute creating an electrical current Any material with low resistance to the flow of current is called a conductor Materials that are poor conductors are referred to as insulators Wires of various sizes and materials are used as conductors today There are four basic elements in an electrical circuit 1 A power source i e 110 440 volts of electromotive force A set of conductors the wires 3 A load any device in a circuit that converts electrical energy to useful wor
43. a constriction in the flow of refrigerant is created in the sealed system This constriction maintains the pressure difference between the high and low side Without continually maintaining this pressure difference the vaporization and liquification of the refrigerant would not be possible When refrigerant reaches the larger space of the evaporator by the suction power of the compressor the low pressures in this environment immediately cause the refrigerant to vaporize and absorb the heat from the evaporator Commonly used in commercial and household refrigerators freezers and window or 32 rooftop type air conditioners capillary tubes are installed between the filter drier on the liquid line and the evaporator If a capillary tube must be replaced for any reason such as a restriction that cannot be cleared with a tube cleaner it is most important to replace it with one of exactly the same length and inside diameter The diameter is measured by a capillary tube sizing kit Capillary tubes are used in different sizes and lengths according to the capacity of the unit see fig 45b 45c 45d 45e Defrost heater It is an electric resistant heating element clipped to the evaporator in frost free refrigerators and freezers The purpose of the defrost heater is to melt the frost accumulated on the evaporator surface during the run cycle AN EVAPORATOR FAN MOTOR A timer takes the unit into the defrost mode causing the defrost heater
44. a switch within the thermostat to open the main circuit to the unit shutting off the system AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 187 Figure 128 ATYPICAL ICE CUBE MAKER Ejmctrir SS In the lower right system water enters the reservoir pan It is then pumped across the top of the evaporator It then flows down the face of the evaporator The unfrozen portion of water flows back to the reservoir to be pumped over the evaporator plate again iy cuplliary fuba i Ice thickness thermostat Evaporator plate Condenser Thermostatic expansion valve Filter drier Pump and float mechanism in th s rT bui reservoir pan comprin Soe explanation bals A TYPICAL COMMERCIAL 3 al power Vappl p ICE MACHINE A WATER CIRCULATING TYPE ICE CUBE MAKER Photo Courtesy of ICE O MATIC a Welbilt Company Asthe water level in the reservoir lowers the water inlet float opens a valve to the water supply to allow the reservoir to refill Water from the reservoir is pumped to the sprayer tube where it is sprayed onto the mold continuously and instantly frozen in thin layers Run off water is returned to the reservoir Ice continues to build until it becomes thick enough to touch a sensor at which time the low temperatures cause the sensor to shut off power to the compressor and water pump and to energize the electric defroster As the eva
45. and not through the heaters It completes its path by flowing back to L2 the neutral terminal in the wall receptacle 316 Lina De Breed i bes Dine f 0 Cycle Lb Comprmessur Tharmcm mi n Evagereie Heater ar MA Dem Drain Hester e bs CMM diee Malligr Bmater ie 1878 Dern Cama Heabzr DT WID dhas Figure 185c THE SCHEMATIC WIRING DIAGRAM OF A CYCLE DEFROST REFRIGERATOR IN THE DEFROSTING CYCLE When the thermostat becomes satisfied opens the defrost cycle will start Note the direction of the flow Power starts from L1 the hot terminal in the wall receptacle flows through the starting relay compressor overload protector evaporator and drain heater and back to L2 the neutral terminal in the wall receptacle to complete its circuit Since the resistances of the evaporator and drain heaters are substantially higher than the resistance of the compressor motor in the circuit the heaters will consume all the power and the compressor will not start although current flows through it See p 292 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 317 A TYPICAL TWO PIPE HOT GAS DEFROST SYSTEM coder Sigh pea Fan Bud Dui Lia Presaura OELJDUE The liquid line solenoid valve becomes energized and Freon flows through an expansion valve to D 1 the evaporator It is AT then drawn back into a
46. called a ground wire color coded green 2 The chassis is grounded in the power receptacle see fig 182 in which the opening marked G is the ground connection The receptacles are connected to ground by a wire leading to an eight foot copper rod which is buried in the earth outside If the receptacle being used is not grounded secure a piece of wire to the chassis and connect the other end to the nearest cold water faucet This will do the job as well since cold water pipes run under the ground It is the amperage not the voltage which is the dangerous ingredient of electricity A very small amount of amperage driven by 120 volts of 60 hertz current can be fatal Dry skin may have from 100 000 to 600 000 of resistance This resistance is reduced to as little as 1 000 when the skin is wet as from perspiration Perhaps less if it is perspiration because sweat contains salt and salt makes moisture a more efficient conductor Using Ohm s law volts divided by ohms equals amperes it can be determined what amperage will be dangerous Experience has shown that 5 10000 to 2 1000 A is just noticeable 5 100 to 2 10 A causes irregular twitching of the heart muscles with no pumping action and anything more than that causes paralysis of breathing With dry skin the current flow through the body would be 120 V per 100 000 Q or 0 0012 12 10 000 A barely noticeable Now if the resistance were lowered to 1000 O through perspiration acc
47. not be circulated back to the compressor OIL PRESSURE SAFETY CONTROLS These controls are made for 2 uosuuor jo sa1no5 If for any reason the oil pressure drops below the low side pressure the pressure switch in the control will shut off the power to the compressor Thistype of control operates the same way as the low pressure control in figure 94 There are two bellows or diaphragms within the pressure control which are set to sense a safe pressure difference between the suction line pressure and the oil pressure If this pressure difference drops below a predetermined point the mechanism will open the circuit to the compressor CHECK VALVES Check valves are used in large commercial systems having multiple evaporators with different temperatures The purpose of the check valve is to keep the liquid or vapor refrigerant flowing in one direction Normally installed at the outlet of the colder evaporator they only permit vapor to AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 145 leave to prevent flooding of the colder evaporator during the off cycle In some units a check valve is placed near the suction line of the compressor to prevent a possible back flow of liquid refrigerant into the compressor during the off cycle See fig 95a DOUBLE TEMPERATURE VALVES Pressure regulating or Pressure reducing Valves In some of the larger commercial units the suction line is connected to a multiple evapora
48. passing through the system or out the faucet decreases The flow of electrical current always follows the path with the least amount of resistance As electrical current reaches a junction in the circuit if the difference in the resistances between the paths branching off is substantial current takes the path s with the least resistance and does not flow through the branch with the substantially higher resistance 296 An electrical circuit with no resistance load is a short Think about it It is just like inserting the two ends of a piece of wire into the two sides of an electrical outlet which will cause a short and blow a fuse or trip a circuit breaker If only a light bulb no matter how small is hooked up on the wire a load it will not blow the fuse When an appliance is properly grounded any electrical short is carried harmlessly to ground since a ground has little or no resistance A good ground can protect both the equipment and the technician should the current be accidentally short circuited into the housing Since electricity follows the path of least resistance should anyone touch a shorted piece of equipment current will not flow through a body that has several thousand ohms of resistance instead it is bled to ground because a grounded circuit has very little resistance EQUIPMENT IS GROUNDED BY THE FOLLOWING METHOD 1 All electrical components in the unit are connected to the chassis by a piece of wire
49. several sizes up to sixty inches long Courtesy of Marvel Industries Division of Northland Corporation AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 17 Generally the lower the temperature the longer the food can be preserved _ BELLA The walls of freezers and refrigerators contain an insulating material to prevent the loss of cold air and to keep heat from penetrating Either urethane foam or fiberglass is used as insulation in almost all units In some commercial and industrial units other materials may be used as well The walls of refrigeration units are made of cold rolled steel and are welded together l nas l e fre S h fo o d IYPR AL TOP par ZE refrigerator the evaporator SHOWING EVAPORATOR LOCATHIN is located in the top of the cabinet and cold air is Figure 6 distributed automatically because cold air is heavy and flows down from the evaporator surface and settles on the bottom of the cabinet see fig 5 In frost free refrigerators cold air from the evaporator is forced into the fresh food compartment by means of a fan because the evaporator and fresh food compartment are separated by a wall More about this later See fig 6 MANUAL DEFROST AND CYCLE DEFROST Manual defrost units are the least expensive and should be defrosted every four weeks in the summer and every eight to ten weeks in the winter Usually the refrigerator is shut off and permitted to
50. sometimes other symbols to indicate the grounded terminal on the capacitor It indicates the pole to which the hot wire is to be connected In the event of a short the current is drained off harmlessly protecting A RULE OF THUMB FOR SELECTING CAPACITORS When replacing a capacitor the voltage rating must be at least as high as the original and the microfarad mfd rating must be as near as possible to the original Sometimes it is impossible to identify a defective capacitor The chart in figure 66a can help you select a capacitor for any unit up to 3 hp Simply determine the horsepower rating of the motor compressor and check the columns next to it for the mfd AC volts for the start or run capacitor you wish to replace Remember the motor operating voltage has little or no bearing to the voltage rating of the capacitor i e a motor that operates on 110 VAC may use a 330 VAC capacitor Capacitor Capacitor Start Run HP Motor Rating MFD MFD VAC VAC 72 88 110 75 90 110 5 370 6 370 7 5 0370 7 5 0440 1000370 1000440 15 370 15 440 15 370 15 440 20 440 20 370 20 370 20 440 1 8 1 6 86 100 110 108 130 110 124 149 110 161 193 110 200 240 110 216 259 110 324 388 110 340 408 110 378 440 110 400 480 110 540 648 110 75 90 250 81 97 250 108 130 250 121 145 250 25 370 25 440 25 370 25 440 20 370 to 35 370 40 440 127 152 330 135 162 330 130
51. turns to ice in the filter drier capillary tube or any other refrigerant control blocking the flow of refrigerant Also caused by wax or other small particles in the sealed system retainer strip A metal or plastic strap used to hold another object in place refrigeration with cycle defrost In these units each time the thermostat is satisfied the evaporator coil is defrosted by an electric heating element or a solenoid is energized shunting hot refrigerant through tubing adjacent to the evaporator coil reversing valve See four way valve saddle valve A type of piercing valve silver brazed to tubing saturated vapor pressure A certain pressure imposed upon vapor refrigerant at which no more refrigerant can vaporize schematic diagram A line drawing of an electrical circuit in which the wiring and components are simplified and depicted as commonly recognized symbols sealed system An airtight passage for refrigerant circulating through the compressor filter drier capillary tube evaporator and condenser self contained unit A refrigerating or air conditioning system in which all of the components of the entire sealed system are contained within the same console 428 sensing bulb A tubular extension of a temperature control device that is filled with refrigerant and attached to the evaporator As temperature changes occur the expansion and contraction of the refrigerant in the tube causes the contacts in the temperature
52. 12 boils at 80 F If the unit operated under this condition in a humid ambient of about 90 liquid line sweating would become evident a sign of too much pressure drop Pressure drop can also be caused by tees elbows rises etc That has to be taken into consideration when designing a refrigeration or air conditioning system Other ways to compensate for the effect of liquid line pressure drop is to add to the amount of refrigerant in the system reduce the number of tees and elbows or increase the diameter of the tubing Oil traps must be installed at the bottom of a suction line vertical rise to preclude the return of a large quantity of oil to the compressor at the moment of starting Generally when multiple evaporators are installed in series the size of the suction and liquid lines must be increased for each evaporator added The cross sectional areas of every additional line feeding multiple evaporators is added to the liquid and suction lines OUTSIDE DIAMETER OF TUBING INCHES 1 4 3 8 1 2 5 8 3 4 7 8 1 18 1 3 8 1 5 8 2 1 8 2 5 8 3 1 8 3 5 8 4 1 EQUIVALENT RESISTANCE IN FEET OF TUBING PER FITTING Figure 178d 90 Elbow 0 75 0 75 10 1 0 15 15 20 25 30 40 50 55 65 75 Tee 15 15 20 20 25 30 40 50 60 75 90 110 13 0 15 0 15 15 20 20 25 30 40 50 60 75 90 110 13 0 15 0 LIQUID LINE REFRIGERANT CHARGE IN LBS FT Figure 178e Liquid line size 1 4 3 8 1 2 5 8 3 4 7 8 14 8 Refrigerant charge 0 015 0 043 0 08
53. 16 750 35 0 32 0 31 8 33 0 22000 40000 5 16 3 8 3 8 3 8 3 8 900 410 37 0 35 5 385 40 000 51 000 3 8 3 8 3 8 3 8 3 8 7 700 640 616 660 53 000 66 000 1 2 1 2 1 2 2 1 2 1500 Courtesy of Tecumseh Product Co Discharge Line If there are too many restrictions in the liquid 18 500 20 000 5 16 3 8 3 8 line or if the liquid line is too small pressure 20 000 22 000 3 8 3 8 3 8 drop will cause insufficient liquid refrigerant flow 22 000 24 000 3 8 3 8 3 8 2 1 2 through the refrigerant control reducing the 24 000 34 000 3 8 3 8 1 2 2 1 2 cooling capacity of the unit As a general rule 38 000 44 000 3 8 1 2 1 2 2 1 2 it is a good practice to choose liquid line tubing 44 000 51 000 3 8 1 2 1 2 2 5 8 about 15 oversized 53 000 66 000 The above figures assume standard refrigeration tubing with a wall thickness of 0 028 inches or 0 032 inches and do not include any consideration for additional pressure drops due to reduced joint sizes elbows or valves Refer to pages 285 to 287 for correct piping method v For each ten feet of tubing over thirty five feet it is necessary to add three fluid ounces of refrigerant Figure 199b CONTROLLING THE HEAD PRESSURE BY CONTROLLING THE CONDENSER FAN SPEED The high side pressure can also be regulated by controlling the condenser fan operation When the fan operates air is blown through the condenser the condenser is
54. 37 3 130 1 30 39 9 41 9 39 7 40 6 22 7 8 32 2 36 0 31 9 33 5 140 1 40 38 2 40 3 38 0 38 9 24 7 10 28 7 32 7 28 4 30 0 150 1 50 36 6 38 8 36 5 37 4 26 7 12 25 2 29 3 25 1 26 6 160 1 60 35 1 37 3 35 0 35 9 27 7 14 22 0 26 2 22 0 23 5 170 1 70 33 7 35 9 33 6 34 5 30 7 16 19 0 23 3 19 1 20 5 180 1 80 32 3 34 6 32 3 33 1 32 7 18 16 1 20 5 16 3 17 7 190 1 90 31 0 33 3 31 0 31 8 34 7 20 13 3 17 9 13 6 15 0 200 2 00 29 7 32 1 29 8 30 6 36 7 22 10 7 15 4 11 1 12 4 210 2 10 28 5 30 9 28 6 29 4 38 7 24 8 2 12 9 8 6 10 0 220 2 20 27 3 29 8 27 4 28 2 40 7 26 5 8 10 6 6 2 7 6 230 2 30 26 2 28 7 26 3 27 1 42 7 28 3 4 8 4 4 0 5 3 240 2 40 25 1 27 6 25 3 26 0 44 7 30 1 2 6 2 1 8 3 1 250 2 50 24 0 26 6 24 2 25 0 46 7 32 1 0 4 1 0 3 1 0 260 2 60 23 0 25 6 23 2 24 0 48 7 34 3 1 2 1 2 4 1 1 270 2 70 22 0 247 22 3 23 0 50 7 36 5 2 0 1 44 3 1 280 2 80 21 23 7 21 3 22 1 52 7 38 TA 1 8 6 3 5 0 290 2 90 20 1 22 8 20 4 21 1 54 7 40 9 1 3 7 8 2 6 9 300 3 00 19 2 21 9 19 5 20 2 56 7 42 10 9 5 5 10 0 8 7 310 3 10 18 3 21 1 18 6 19 4 58 7 44 12 8 7 2 11 8 10 5 320 3 20 17 4 20 2 17 8 18 5 60 7 46 14 5 8 9 13 5 12 2 330 3 30 16 5 19 4 16 9 17 7 62 7 48 16 3 10 6 15 2 13 9 340 3 40 15 7 18 6 16 1 16 8 64 7 50 18 0 12 2 168 15 6 350 3 50 14 9 17 8 15 3 16 0 66 7 52 19 6 13 8 18 4 17 2 360 3 60
55. 4 60 4 70 6 56 2 450 4 50 12 0 12 4 12 4 180 10 1 74 60 619 620 619 722 57 7 475 4 75 13 9 14 1 14 0 197 118 76 7 62 63 6 634 63 4 73 7 59 2 500 5 00 15 6 15 7 15 7 214 13 4 78 7 64 65 2 649 64 9 75 3 60 7 525 5 25 17 3 17 2 17 2 23 0 14 9 80 7 66 668 664 66 4 76 8 62 2 550 5 50 18 9 18 7 18 7 24 164 82 7 68 68 4 678 67 8 78 2 63 6 575 5 75 20 5 20 2 20 2 260 178 84 7 70 69 9 69 2 69 2 79 7 65 0 600 6 00 22 0 21 5 216 27 4 19 2 86 7 72 71 4 70 6 70 6 811 66 4 625 6 25 23 5 22 9 22 9 28 8 20 6 88 7 74 72 9 71 9 72 0 82 5 67 7 650 6 50 24 9 24 2 242 30 2 21 9 90 7 76 74 3 73 2 73 3 83 9 69 1 675 6 75 26 3 25 5 25 5 315 232 700 7 00 27 7 26 7 268 327 244 725 7 25 29 0 27 9 28 0 340 25 6 Inches of mercury NOTE kPa and Bar are absolute pressure Used by permission of DuPont Fluoroproducts psiG The numbers in parentheses the reading on the manifold gauge 416 SATURATED VAPOR TEMPERATURES OF R502 AND ITS SUVA REPLACEMENTS Temperature F Temperature C psiA kPA psiG R502 HP80 HP81 HP62 Bar R502 HP80 81 HP62 12 2 5 56 8 59 7 55 8 57 7 80 0 80 50 4 51 9 49 8 50 8 14 7 0 49 7 52 9 49 0 50 8 100 1 00 45 7 47 4 453 46 3 16 7 2 44 8 48 1 44 1 45 9 110 1 10 43 6 45 5 43 3 44 2 18 7 4 40 2 43 8 39 7 41 4 120 1 20 41 7 43 6 41 4 42 4 20 7 6 36 0 39 7 35 7
56. 45 F depending on their use and some are equipped with ultraviolet lamps to retard bacteria growth If the unit is used as a freezer the cabinet temperature ranges between 10 F and 30 F and 50 F to 55 F for a floral display and storage case For better insulation double glass doors and windows are used in these units Field Assembly 1 Place floor panels into position and level Cam lock together 2 Start wall assembly by locking a wall panel and wall panel together Complete wall assembly Start ceiling assembly by locking top panel to side wall Complete ceiling assembly Install self contained or remote refrigeration Bw ou Walk in coolers and freezers can use any number or combination of evaporator units illustrated above The condensing units are installed on the top of the unit on the roof ofthe building or in the alley at the rear of the business Top left is a combination walk in reach in and product display unit Center left Shows how a portable unit is assembled and bottom left an assembled multiple unit Lower right is a floral display case with the condensing unit on top T Courtesy of Buchbinder n Courtesy of RAM Chicago Illinois Freezers and Coolers Manufacturing Inc it FP L AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 215 Courtesy of RAM Freezers and Coolers Manufacturing Inc i V 9deJaAag Asayino Food
57. 87 93 101 108 117 125 USED FOR VARIOUS SYSTEMS R 22 95 104 113 123 133 144 155 158 180 194 208 AND REFRIGERANT TYPES R 717 98 108 119 130 140 152 164 177 191 205 220 R 500 71 78 86 94 112 121 131 142 153 165 Figure 214 R 502 116 126 137 147 160 173 186 200 214 230 246 Figure 214c HOW TO REMOVE A WATER VALVE Disconnect power to the unit Disconnect the water valve wires from the unit Close the manual water shut off valve Remove this valve from the system If the valve pressure tube is connected into the cylinder head of the compressor proceed as follows a After connecting the gauge manifold to the system turn the suction line service valve all the way clockwise b Turn on the compressor until pressure in the crankcase drops to 0 psi Using a heat lamp heat the valve and line for about five minutes to move the liquid refrigerant that has condensed in the valve and this tube back into the condensing unit Turn the discharge service valve all the way clockwise Open both manifold valves The high pressure in the water valve refrigerant line and the manifold bypasses to the low side Heat the water valve again being aware that no one is standing in front of the line as any remaining refrigerant is released with considerable force SERVICING A COOLING WATER TOWER The accumulation of w
58. COMMERCIAL AND RESIDENTIAL UNITS Problem and Possible Cause Remedy Compressor Hums But Will Not Start Cycling on Overload Contacts in relay not closing Wired wrong Start winding open or shorted Low voltage Discharge pressure too high 6 Frozen compressor Compressor Will Not Run Electrical control open such as a pressure control thermostat etc No power Blown fuse or tripped breaker Motor or compressor frozen Overload relay tripped Control location too cold Compressor piston stuck Compressor Runs Only on Start Winding Run windings shorted Shorted run capacitor Weak start capacitor Line voltage too low Discharge pressure too high Faulty relay Wired wrong Run Capacitor Burnout Check and replace relay if necessary Check wiring with schematic diagram Check winding replace compressor if necessary Check voltage at source to determine that it is not more than a 10 drop Check for excessive amount of Freon restriction linted condenser bad condenser fan and that discharge service is fully open Check replace if necessary Check replace if necessary Check power source fuses or circuit breakers Replace fuse or reset breaker Replace compressor if all else is OK Reset overload switch Relocate to warmer place where it will function properly On other than hermetic compressors remove head and check for broken or jammed parts Replace hermetic
59. CONDITIONING AND REFRIGERATION REPAIR MADE EASY 275 Total 42 600 Btu divided by 12 000 3 55 tons Thus a 3 to 4 ton unit should do the job quite well Choose the smaller unit if the shop is well insulated from the outside as in a mall or use the next larger unit if the area to be air conditioned is in a free standing building The chart on the next page is used to quickly determine the general tonnage requirement of an air conditioner for two small rooms or a small house When deciding on a unit keep in mind that the percentage difference is important and not the number of tons For example if a thirty ton unit is determined to be suitable for a building and the closest unit available is rated at thirty tons the result will be satisfactory because the difference between thirty and thirty two tons is less than 1096 whereas if a two ton unit is substituted for one ton equipment the difference will be 10096 In which case the conditioned area will feel uncomfortable because of the excessive humidity The air conditioner will cool the area too fast and the thermostat will become satisfied too soon shutting off the compressor too quickly This will cause the unit to stay off most of the time During the off cycle the evaporator is no longer cold enough to condense the excess humidity That is why the conditioned area will remain too humid Thus a two ton unit will cool the area too fast preventing the humid air from condensing on the cold
60. Cause i Liquid refrigerant backed in condenser Refrigerant overcharge Receiver too small for flooded head pressure control system in summer operation Fan pressure switch out of calibration Higher rate of infiltration of ambient air inside cabinet than designed Condenser air recirculation Condenser tubing restricted internally or by physical damage Ambient conditions exceed design limitations 375 Remedy p Check for faulty flooded type head pressure control valves Charge properly Sec 11 1 Replace with correct size liquid receiver Reset or replace as needed Correct air infiltration Panel missing or exhaust fans from elsewhere discharging under or close to condenser air intake Change airflow direction Replace condenser Reevaluate suitability of unit for the application Failure of Flooded Head Pressure Control System Constant Bypass Pressure drop through condenser exceeds 20 psi forcing bypass port partially open Bypass port wedged open due to foreign material between seat and seat disc Bypass port seat damaged or worn Wrong pressure dome in valve for system refrigerant Bypass check valve in backward Pressure of condenser bypass regulator OPR set too high Applies to water cooled condensers Change condenser to reduce pressure drop below 20 psi Artificially reduce head pressure and tap valve body with system running to dislodge foreign material
61. Compressor Never Stops Running Compressor has low compression Low refrigerant charge Linted condenser coil System overcharged Faulty low pressure control Overload Protector Causes Compressor to Short Cycle Faulty overload protector Faulty start relay Faulty start capacitor Linted condenser Restriction or overcharge Freezer Is Too Warm with Compressor Running Cold control set wrong Bad door gasket Faulty compressor Undercharged system Remedy Add refrigerant Replace filter drier if it feels cold Remove and clean if valve frosted Inspect tubing repair as necessary Adjust valve stem for higher flow Replace evaporator fan Check for leak repair as necessary Check head and back pressures for leaks and check low pressure switch Depress reset button Check for adequate water supply Depress reset button Verify thermostat is on and power at the valve Check voltage notify owner to call electrician for remedy Check and replace if necessary Check and replace if necessary Test replace if necessary Add refrigerant Clean condenser coil Discharge an appropriate amount of refrigerant Check and replace if necessary Check replace if necessary Check replace if necessary Check replace if necessary Clean condenser coils Check for restriction and or discharge refrigerant as necessary Adjust thermostat and or recalibrate cut in and cut out pressure control
62. E mi TEIT FH Ba ERHETO j t C 16 A Leak Detector using a propane amet T T PM Th am flame Trace lines with flame mri 10 Blue flame turns green when leak is found Courtesy of Robinair Div SPX Corp AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 89 CAPACITORS Capacitors See Fig 65 increase the power factor and efficiency of electric motors Voltage is accumulated on one pole and when charged to capacity it is released to the other This is done in rapid succession Start capacitors provide extra voltage to enable the motor to start easier while drawing less amperage Run capacitors provide more energy to the motor run winding to help it run easier Capacitor capacitance is measured in Micro Farads LI j Lower mBlcrofarad type men capacitor Higher rated type for up 1 J tearminal center commen Tor xir coed Ei ore i Biechargiog a capacitor see beran TO PREVENT THE POSSIBILITY OF SEVERE SHOCK DISCHARGE THE CAPACITOR BEFORE TOUCHING IT Discharge capacitors by shorting the terminals with an insulated screwdriver described in Testing Capacitors Very often a compressor may not start or short cycle due to a bad capacitor Some capacitors are used to help motors start They are called start capacitors They are wired in series with the compressor start winding an
63. F below the desired temperature produced Therefore 20 F 20 F 40 F Referring to the temperature pressure chart at 40 F the corresponding pressure for units using refrigerant 502 is 4 3 psi which should be the low side pressure To determine the high side pressure add 30 F to 80 F which will be equal to 110 F The corresponding pressure on the chart in the R 502 column at 110 F is 245 8 psi the proper head pressure for this unit in this environment EXAMPLE 1 What evaporator temperature is required to maintain the cabinet temperature of a floral display case at 40 F 136 ANSWER 40 F 20 F 20 F EXAMPLE 2 Suppose service is needed ona delicatessen case with a cabinet temperature of 35 F using refrigerant R 12 The ambient temperature is 75 F Determine the high and low side pressures ANSWER The evaporator temperature should be regulated at 15 F 35 F 20 F 15 F According to the chart 17 7 psi back pressure is required for R 12 to create 15 F To determine the high side pressure 75 F 30 F 105 F On the chart the corresponding pressure for 105 F in the refrigerant R 12 column is 126 6 psi EXAMPLE 3 Determine the head and back pressures of a frozen yogurt machine which uses R 502 with evaporator temperature of 10 F The condenser is cooled by water which is in tubes that run through the condenser coil Many commercial units have water cooled condensers for improved heat exc
64. If there is no service valve on the suction line install one and leave it closed b Remove the evaporator cover Using this charging method becomes necessary when working on a unit where the charging information is not available or where an ammeter or a charging cylinder or a charging scale is not available Connect a refrigerant tank to the compound gauge on the manifold and also to the piercing valve as indicated in figure 81 d Turnon the unit e Turnonthe piercing valve the gauge manifold and the refrigerant tank as in figure 81 f Keep a hand on the valve of the refrigerant tank while watching the frost pattern appear on the evaporator Let the refrigerant flow into the system while the unit runs g The frost pattern will appear and advance on the evaporator coil Once the frost pattern covers all of the evaporator coil close the valve on the refrigerant tank the gauge manifold and the piercing valve h Remove the hoses from the unit Put some Teflon tape on the threads of the piercing valve and replace the cap CHARGING THE UNIT BY THE LOW SIDE GAUGE PRESSURE METHOD This method is widely used in commercial refrigeration since the exact back pressure requirement is known This is explained in Saturated Vapor Refrigerant Pressure and Temperature Relationship The correct low side pressures of all residential units made in the USA can be obtained from the Tech Master publication mentioned on page 112 All that
65. LOW CAPACITY COMPRESSOR Courtesy of Robinair Division SPX Corporation 70 A heavy accumulation of soft frost on the evaporator coil that can be easily removed Low side pressure reads higher than normal High side pressure reads lower than normal Low amperage reading when unit is running as compared with the FLA on the unit nameplate Get an amperage reading from the wire connected to either the run or common terminal See fig 124 The unit runs constantly When a residential unit is running frost covering the accumulator disappears very quickly when the accumulator is held in the hand A LOW CAPACITY COMPRESSOR MUST BE REPLACED TESTING STARTING RELAYS The starting relay provides power to the start winding of the compressor during start up for approximately three seconds At this time the compressor reaches about 75 of its running speed the relay shuts off the power to the start winding and the compressor run winding continues to run the motor and bring it up to its normal speed See fig 46 These relays used in residential units are mounted on the compressor terminals under the terminal cover Basically they are of two types those with two electrical terminals and those with three In both cases they are connected directly to the compressor run and start terminals NOTE Pay particular attention to the word TOP on start relays If relays are not mounted right side up they will never open the circuit to th
66. PAN OTOA KAMEFLATE jira Cos As explained earlier the model number is needed to replace a part The serial number usually indicates the age of the unit Next to the type of refrigerant R 12 R 22 etc the charge requirement may be shown in pounds and or ounces The FLA and LRA amperage on the nameplate indicate the amount of current drawn by a good compressor under normal conditions These are the figures AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 123 by which comparisons are made in diagnosing the situations mentioned earlier Also see figs 64a 64b and 80 TRACING REFRIGERANT LEAKS IN THE SEALED SYSTEM When lower than normal pressures are observed on both the high and low sides and the system does not cool properly look for a refrigerant leak This is done with a leak detector see fig 82a Pass the probe of the detector over the suspected joints in the system As the leak is approached the detector gives off a piercing sound Some leak detectors also come with a light that flashes Some are sensitive enough to detect a leak of as little as 0 05 ounce per year Before getting into the repair procedures note that there are systems of either copper or aluminum Should you receive a call from a home owner stating that he she has poked a hole in the evaporator in an attempt to more quickly defrost it it may be concluded that it is a manual or cycle defrost refrigerator and that the evaporat
67. Pick a spot and place a piece of paper between the gasket and door jamb With the door closed pull it around the perimeter of the door If the gasket is fitted properly the paper will offer some resistance as it is being pulled An air leak can occur where the paper offers no resistance If a corner is not sealing a loosen half the gasket screws starting from that point to the two nearest corners b with the door open twist the door from that particular corner toward the door jamb hold it in that position and tighten the screws C if you notice any cracks or breaks in the door liner around the screw hole hold the liner and gasket in position see fig 73a remove the screw from that particular hole pass the screw through a metal tab to hold the liner in place and then screw it into the door assembly 2 Thevertical and horizontal adjustment of the door is made by the hinge with elongated holes at the top of the door In chest type freezers there are two hinges at the back of the lid If the gasket is not sealing on one side proceed as follows a Loosen the hinge screws at the top or on the back hinges b Force the door into its proper position To do this you will have to force the door against the jamb in a way that all four corners of the gasket are flush and sealing Hold the door in that position while tightening the screws on the hinge You may have to repeat step 2b for proper door adjustment If you still observ
68. REPAIR MADE EASY 263 3 With a small screwdriver recalibrate the thermostat to match the temperature reading of the accurate thermometer TESTING A WALL THERMOSTAT When a certain component in the unit fails to start and the wall thermostat is suspected to be the problem disconnect the unit from the power supply in split systems disconnect the furnace from the 120 VAC power 1 Remove the thermostat cover and the base from the sub base 2 Remove the wires that energize the cycle that has failed and connect them directly together then reconnect the power The thermostat is now bypassed and if the unit starts that proves the thermostat is bad and will have to be replaced Otherwise the thermostat is OK and the answer to the problem is to be sought elsewhere Reconnect the wires to their appropriate terminals and put back the thermostat base and cover Before running these tests bear in mind that only the red wire is hot Other wires will only become energized when they are connected to the red wire Disconnect power to the unit connect the appropriate wires together and then reconnect power to the unit to check for results Connect red and yellow wires to energize the contactor coil which will energize the compressor and the condenser fan Connect red and green wires to energize the plenum blower relay causing the plenum blower to operate Connect the red yellow and green wires together to energize the entire cooling system se
69. Remove the wall plate from the the top of the base fig 3 Swing thermostat fig 1 down and press on lower edge until Install the mounting plate on the wall thermostat snaps into place fig 4 as instructed on page 234 Be sure to Tighten the captive mounting connect every wire to its color coded screws fig 5 connection on the unit fig 2 MOUNTING A DIGITAL THERMOMETER ON THE WALL Courtesy of Honeywell RECALIBRATING THE THERMOSTAT THERMOMETER If it is suspected that the thermometer of the thermostat is not giving an accurate reading it may seem too warm or too cool for the indicated temperature check it first with a thermometer known to be accurate If there is a significant temperature difference the thermometer can be recalibrated 1 Remove the cover The thermometer adjusting screw is in the back of the cover See fig 173 a Thermostat cali calibration screw in back of thermostat cover Lo Figure 173 TYPICAL HEATING AND COOLING WIRING B a a T p zs b Left The drawing shows ei I astep down transformer DOTEN ninm providing low voltage FAS SME Courtesy of White Rodgers Division current to the wall of Emerson Electric Company thermostat terminals 2 Place the thermostat thermometer close to the accurate one Wait for about three minutes for the temperatures to stabilize AIR CONDITIONING AND REFRIGERATION
70. Split phase compressor generally used start windings used mainly in in residential and commercial units i den A capacitor start compressor used in residential units with limited coinmercialeg ipm nt use in small commercial units A rotary compressor 2 Capacitor start induction run Courtesy of Tecumseh Products Company motor Capacitor start capacitor run motor 4 Permanent split capacitor run motor po Figure 42 1 Split phase hermetic is the simplest kind used mostly for household refrigerators since the compressor motors do not require alot Typical wiring for a hermetic of starting torque In these split phase compressor motor operating units when the thermostat shuts the system down the high and low side pressures equalize through the capillary tube In heavy commercial N Typical wiring of a hermetic units the pressures do not split phase compressor motor equalize because they use peg M operating on a potential type TEV thermostatic electric relay valve or automatic valves covered later as well as capillary tubes These valves isolate the high and low sides and the pressures in the system do not equalize very easily in the off cycle In these motors a relay controls the engagement of the start windings The starting relay used may be of the thermal type the current type or the potential type which will be covered later Capacitor s
71. THE METHOD EP LECT A LT caning fm prue ELECT 1 hes Charging increase the pressure and cause the liquid or gas to be expelled faster hold the container under your coat next to your body or put it on a Prams L condenser to warm it In severely cold weather use a refrigerant container heating blanket such as ar rna caer the one pictured above If an electric blanket is not available it is also possible to increase the pressure in the refrigerant container by placing it in a tub of warm water at the time of charging Before charging a unit purge all charging hoses to rid them of moisture and air Commercial systems may also be charged by the high side method as shown in figure 80a The system must be turned off when it is being charged through the high side This method is used only if the entire amount of refrigerant has been removed from the system The inverted refrigerant container is placed on a scale and the unit is charged until the proper amount of liquid refrigerant is transferred into the system PUTTS RETREGERANT WTU A CHABDING CYLINDER 118 TROUBLESHOOTING RESIDENTIAL REFRIGERATING UNITS PROBLEM POSSIBLE CAUSE REMEDY Unit won t start Unit runs continuously Freezer and fresh food compartments too warm Low voltage or no power Bad power cord Bad starting relay Broken thermostat Defective timer Bad thermost
72. Tn In heavier commercial compressors adjusting the oil level is made easier by the placement of a sight glass in the crankcase of the compressor Be sure to use the oil specified by the manufacturer Compr ea oor CoBpraeasmar SN Buetion Line e An oil separator is placed in the discharge line As oil separates from the refrigerant it collects at the bottom until the float rises enough to open the needle valve to allow the oil to be drawn back into the compressor AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 155 COMPRESSOR SERVICE VALVES Commercial refrigeration units are equipped with permanent service access valves which make the service technician s job much easier With these valves already in place installation of piercing valves becomes unnecessary Some units come with a valve installed directly on the compressor suction opening see figs 100 and 118 and one connected to the receiver see figs 101 and 118 Many bolted type compressors are equipped with suction and discharge valves connected to the compressor housing fig 120 The valves seal off the system by turning the valve stems all the way clockwise and trap the refrigerant in the sealed system By removing the bolts connecting the valves to the compressor housing they can be removed and reconnected to the new compressor in a few minutes without breaking into the sealed system and having to do the regular procedures of evacua
73. Unless the tubing is supported around its circumference it will flatten at the bend and possibly crack causing it to leak Use a tool called a bending spring shown here in figure 27 on the right The bending springs are inexpensive and do the job properly Place the spring over the tubing at the area to be bent then bend it slowly and carefully making a curve as large as practical The larger the bend the less likely it will be flattened or kinked Never try to complete a curve in one stroke Do it in short stages until the appropriate curve is made Remove the spring by twisting while sliding it off A SPRING TYPE TUBING BENDER sjonpoud 40 Asaqnog For tubing larger than one half inch in diameter a bending lever with a flange attached to the end is used See illustration below Figure 27a Spring type benders upper right make it easy to form bends by hand without collapsing the tubing They can also be used to protect tubing during installation and repair procedures The special coil spring wire easily slips over the outside of the tubing and the belled end simplifies insertion and removal The lever type tubing benders illustrated on the left are used for the larger sizes of tubing as they require considerably more effort to bend The curved radius on the stationary bar has a scale in degrees When the movable lever bends the tubing its index mark indicates the degree of the curve The lever type sh
74. a bright yellow or green ring around the leak hole which is visible only under ultraviolet UV light You can find battery operated UV lights on the market to serve this purpose These additives are capable of detecting leaks a low as 0 25 oz per year It is important to use only the type of fluorescent additive compatible with the lubricant and refrigerant being used in the system If you have any doubt AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 403 about the use of any specific additive contact the fluorescent additive manufacturers for detailed information The only disadvantage with the use of additives is that certain parts of a sealed system may be hard to reach and unobservable SUVA MP 66 REFRIGERANT This is the recommended environmentally acceptable alternative for refrigerant R 12 used in low temperature systems with evaporator temperatures below 10 F 23 such as commercial and residential freezers transport refrigeration equipment ice machines etc It can also be used as an acceptable alternative for existing R 500 systems SUVA MP 66 and 39 will decompose if exposed to high temperature producing elements such as electrical resistant heaters open flames etc The pungent odors produced by decomposition may irritate the nose and throat SUVA MP 66 comes in 30 lb 12 Ib and 1700 Ib containers color coded light gray green Nylon hose is recommended for use with this refrigerant Existing low temperat
75. a conventional pressure controlled system Being electrically operated the thermal electric valve does not depend on system pressure or temperature nor does it need a charged element or capillary line It can be used in any type of system with any noncorrosive refrigerant And itautomatically compensates for head pressure evaporator 383 384 load and ambient conditions The electric valve figs 107 and 207 is operated by low voltage current It has two working parts a wire wound bimetal heater and a spring loaded needle At zero voltage the valve is closed As voltage is applied the heater deflects the bimetal upward The spring loaded needle rises as it follows the movement of the bimetal and opens the valve the more voltage applied the greater the opening See figs 208 and 209 Voltage to the valve is regulated by a liquid sensing thermistor This thermistor is installed in the suction line at the exact point where a complete change of refrigerant from liquid to vapor is desired The thermistor reacts to the amount of liquid refrigerant as it leaves the evaporator Figures 210 and 211 illustrate the operation of the thermistor and the electric valve when they are wired in series This is a system in which the valve and thermistor replace a thermostatic expansion valve Voltage input to the valve heater depends on thermistor resistance When it is exposed to hot refrigerant gas the thermistor self heats This lowers
76. and Low Superheat This can be caused by incorrect sizing or distributor and or valve orifice The distributor tubes must be of equal dimension and length see fig 200 Liquid can short circuit through unequally loaded passages and throttle the valve cause it to react prematurely before all passages have received sufficient refrigerant Liquid traps should be avoided when mounting the distributor tubes NOTE At proper load there should be no more than 5 F difference between any two circuits before they enter the header AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 373 11 13 Faulty TEV or Wrong Charge in Sensing Bulb and Low Superheat Depending on the type of charge the TEV could starve or flood Replace the valve with the proper TEV and correct charge in accordance with the evaporator requirements Also see section Il 5 on poor bulb and equalizer location 11 14 Interrupted Pumpdown and Low Superheat An interrupted pumpdown leaves refrigerant in the low side in the off cycle causing possible flooding when the system restarts Find the cause of the interruption and adjust the control to a lower suction pressure if necessary 11 15 Oversized TEV and Low Superheat An oversized TEV results in flooding to the suction line and low or negative superheat You need to replace the TEV with one correctly sized per the information in Section 1 9 11 16 Cold Suction Line or Compressor Location Encourages Liquid Migration to th
77. and compressor Turn valve stem for higher flow Replace evaporator fan Adjust valve for lower flow Replace compressor Discharge excess refrigerant Add refrigerant Repair or replace valve Reduce water flow to condenser Adjust turn stem clockwise or replace valve Clean condenser remove obstruction Evacuate and recharge system increase water flow and check lines and pump Discharge excess refrigerant Increase water flow to condenser clean clogged water pump strainer or lines Increase water flow Discharge excess refrigerant Adjust high pressure cut out Check replace water failure switch Check pump and motor Check water strainer valves and lines Low Pressure Control Causes Compressor to Short Cycle 1 Too much frost on evaporator 2 Refrigerant control valve screen clogged 1 Defrost evaporator coil 2 Remove and clean screens AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 217 Problem and Possible Cause Low refrigerant charge Restriction in liquid line filter drier Clogged expansion valve strainer Kinked tubing Insufficient refrigerant passing through valve Evaporator fan runs too slow Compressor Will Not Start Unit low on refrigerant Low pressure cut out open leak High pressure cutout open Water failure switch open Overload has disconnected power Solenoid valve closed Low line voltage Defective start relay Defective compressor
78. and removed from the rest of the sealed system without having to discharge the refrigerant from the system see figs 119 32 The service valves are bolted to the compressor housing with two bolts from one side and connected to the tubing by flared connections from the other side TESTING THE EFFICIENCY OF A COMPRESSOR CAUTION Conduct this test only with the cranking motor Refrain from running the motor to prevent pressure from climbing to a dangerous level too fast When the unit does not cool as well as it is expected to and the compressor is suspected to be inefficient an inability to pump conduct this test as indicated in figure 45h for residential units Testing the efficiency of commercial units is an easy task because they come with service valves This eliminates the necessity of installing piercing valves and pinching off tubing See figs 100 101 102 TESTING THE EFFICIENCY OF A COMMERCIAL OR RESIDENTIAL COMPRESSOR Remove the valve stem caps and gauge connection caps from compressor discharge and suction valves and connect your gauges to the valves compound gage to the suction and high pressure gauge to the discharge valve With the help of a service wrench turn the discharge valve stem all the way clockwise and crack open the suction valve gauge port by turning the suction valve stem 1 2 aturn clockwise and turn on the compressor and observe your low pressure gauge The compound gauge reading should drop to 29
79. attention Usually SUVA refrigerant vapors have little or ignorable effect on eyes or skin However overexposure to some SUVA refrigerant blends such as SUVA 123 vapor refrigerant can cause a mild to moderate eye irritation blurring of vision or tearing If liquid SUVA refrigerant blends come in contact with eyes or skin they can cause frostbite They can freeze eyes or skin on contact In which case immediately soak the exposed areas in lukewarm water for about ten to fifteen minutes and seek medical attention LEAK DETECTION There are two categories of leak detectors area monitors and leak pinpointers Area monitors are installed to signal the presence of a concentration of any targeted compound in an entire room on a continual basis Leak pinpointers are used when servicing equipment see fig 82a and 218 There are three types of leak detectors 1 Nonselective 2 Halogen selective 3 Compound selective l NONSELECTIVE LEAK DETECTORS These leak detectors are very durable simple to use and inexpensive They detect any type of vapor or emission indiscriminately Due to their insensitivity incapability to be calibrated and lack of selectivity their use for area monitoring is very limited Many nonselective leak detectors on the market today are not sufficiently sensitive for use with SUVA MP 402 refrigerants In fact where SUVA MP components are concerned such as HCFC 22 even leak detectors made especially for th
80. automatically controlled and maintained by the thermostat setting Thermostats are designed to control heating cooling or both They come in a variety of styles and sizes The wire terminals in wall thermostats are color coded Each colored wire is connected to its appropriate terminal which is marked with a corresponding color Normally R stands for the red wire representing the common hot wire G stands for the green wire which energizes the plenum fan motor relay Y stands for the yellow wire energizing the compressor contactor in the cooling cycle W stands for the white wire energizing the appropriate contactor or relay s for heating O for the orange wire which energizes the reversing valve relay to take the heat pumps into the cooling cycle if the reversing valve is energized on a call for cooling The wire connected to terminal B is energized to take the heat pump into the heating mode by energizing the reversing valve if the valve is energized on a call for heat See figure 173 and figure 4 on page 352 However if the wall thermostat is not used in a heat pump system terminals O and B can be used for such applications as electronic air cleaners zone damper controls or humidifiers see fig 1 on page 353 RH and RC shown on the thermostat sub base are connected to the red wire RC represents the thermostat common hot terminal for the cooling cycle RH represents the thermostat common hot terminal for the heating cycle See
81. be due to a dirty or linked condenser Even if the condenser appears clean on the outside dirt accumulated at the base of the fins and coil can prevent proper heat exchange and keep the unit from cooling Furthermore particularly in the case of roof mounted condensers make certain they are protected from direct exposure to the sun and have adequate shade to assist in the cooling process A unit left exposed to the sun absorbs so much heat that it becomes incapable of transferring heat necessary to change the hot vapor refrigerant back to its liquid state When 182 this happens the head pressure will rise above normal The temperature will never drop low enough to satisfy the cold control causing the compressor to run continuously Eventually the overheated compressor will cycle on overload Do not rely on natural shading taller buildings trees etc It will be necessary to build a structure over the condensing unit if one is not already provided The symptoms are often misdiagnosed as a bad compressor or a weak overload protector SYMPTOMS OF AN OVERCHARGED SYSTEM There are several symptoms that indicate the presence of an excessive amount of refrigerant in the system 1 Long running time of the unit When there is too much refrigerant in the system the unit runs for an exceedingly long period of time before the temperature drops to the point where the thermostat becomes satisfied and shuts off the compressor This increase in
82. become energized while the defrost heater remains de energized Courtesy of Eaton Corporation Controls Division F i 1 i AZ m 24 The four timer terminals are numbered on the back Plastic tubing Figure 11c When air which contains moisture used as insulators comesincontact withacold evaporator coil the moisture condensates and immediately changes to a layer of ice If the evaporator coil is not heated from time to time the accumulation of ice willinsulate the coil preventing it from absorbing the heat from its surrounding air inside the unit and the unit will lose its ability to cool When the unit is in the defrost mode the defrost heaters are energized and the evaporator fan s de energized The timer block connects the timer to the system in such a way that it The water produced by the melted ice cannot be installed incorrectly flows by gravity through a plastic pipe and collects in a tray on or beside the compressor where it is heated and Figure 11d evaporated by the condenser and the heat from the compressor In many models an electric heating element is placed around the inlet of the drain tube It is wired into the defrost heater circuit Every time the timer takes the unit into Timer Mounting Bracket the defrost mode this drain heater is also energized to prevent drain water from freezing in the drain line Thee Rourtlng esc Figure 11e and clogging it 5 a 9
83. build up on the coil used in commercial The temperature in the and residential units A commercial double freezer compartment Shaftoten Im OPE will rise from 10 F Fan blades may be to O F or higher As a obtained separately result the temperature in the fresh food compartment will rise to room temperature The same thing happens in air conditioners If the evaporator blower fails air will no longer be circulated through the cold evaporator fins causing an accumulation of ice on the evaporator plate and a sudden temperature rise in the air conditioned area uonejodJo pue u1JoN UOLS seuisnpuj JO Aseunoo sed snoueA Condenser fan In automatic defrost freezers and refrigerators and in larger capacity units that require a more rapid cooling of the condenser additional air movement through the condenser is provided by a fan called forced draft cooling Air is drawn into the compressor compartment from one side of the front grille circulated through the condenser and expelled through the other side of the front grille In some side by side models air is expelled at the rear of the compressor compartment In addition to the rapid cooling of the condenser the condenser fan also causes rapid evaporation of water in the condensation tray 34 UNIT IN THE DEFROST CYCLE UNIT IN THE COOLING CYCLE Figure 16 Accomulator emp Lae peg lla E Fld F Iepe 8 HOW A HOT GAS DEFROST S
84. cOS H OOS Y ccu ed A 1ue1e814Jay isd eansseuq 4m aunjesadway do ZTL Y COS Y 006 cCC H ed isd aunssald aunjyesaduay To convert degree Fahrenheit to degree centigrade use this formula To convert degree centigrade to degree Fahrenheit use this formula 32 5 9 AR C x9 5 32 134 EXAMPLE To determine the corresponding low side pressure to produce the desired evaporator temperature of 33 F in a walk in cooler using R 12 refrigerant refer to the temperature pressure chart ANSWER Across the line on which 33 F is shown in the R 12 column find 30 9 as the pressure needed to produce 33 F Charge the system until the compound gauge low pressure side reaches 30 9 Ibs in turn off the valve and stop charging The cabinet temperatures in different types of refrigeration units are fairly standard Figure 86 shows recommended cabinet temperatures for different units As a rule of thumb evaporator temperature should be set 20 F lower than the desired cabinet temperature EXAMPLE To determine the required low side pressure in a unit using R 12 to maintain a general cabinet temperature of 45 F subtract 20 F from the cabinet temperature to get 25 45 20 25 ANSWER Referring to the chart across the line from 25 F in the R 12 column 24 6 psi is the required low side pressure to maintain the general cabinet temperature at 45 F T
85. cabinet from outside air gauge high or low pressure Measures pressure in pounds per square inch psi A refrigeration gauge scale reads up to 500 Ib in the low pressure gauge is capable of measuring vacuum in inches of mercury inHg ground The connection to transfer excess electrical current to earth used to protect personnel from accidental electrical shock ground wire A safety device Usually a third wire from the unit to a ground source to carry off excess electrical current guardette Another name for an overload protector head pressure Another name for high side or discharge pressure heat A form of energy which causes a body to rise in temperature heat exchanger residential units That part of the sealed system where the capillary tube and suction line are joined side by side for the purpose of transferring heat as is passes through heat pump An air conditioner capable of heating as well as cooling by the use of a four way valve which reverses the direction of refrigerant flow hermetic compressor A compressor and its motor sealed within a metal housing Hermetically sealed hermetic system Refers to the hermetic compressor commonly found in residential and small commercial units high pressure gauge An instrument used for measuring pressures above atmospheric pressure in the high side of the sealed system high side The parts of the sealed system that are under high pressure condensing pressure inc
86. causes for the fan to run when the compressor does not p 277 Why is humidity increased when air is cooled p 226 How is Btu converted to tonnage p 227 Why are there two expansion valves installed in a heat pump p 262 What is the function of check valves in a heat pump p 265 What are the six main functions of an air conditioner p 265 228 What is the function of a slinger fan blade in a window or wall unit pp 231 232 What role does a reversing valve play in a heat pump p 265 What is the other term for a reversing valve p 265 What color is the hot common wire connected to a wall thermostat p 257 Why should a window unit be installed with the rear edge one fourth inch lower than the front p 232 What two types of fans are most commonly used in air conditioners p 233 Why are time delayed relays used in air conditioners p 263 How is a wall thermostat for an air conditioner tested p 263 Where should a wall thermostat for an air conditioner be installed p 259 What kind of a compressor motor is used in a wall air conditioner p 235 Where is the thermostat bulb fastened in a wall air conditioner p 235 What color is the evaporator fan wire in a wall thermostat p 257 In a wall thermostat what does the white wire represent p 257 How is the required tonnage determined for a new air conditioner p 274 275 and 276 What are the two methods for checking a transfor
87. coil iced or dirty See sec 11 19 Check and repair defrost system clean evaporator and or drains Refrigerated or air conditioned space has Determine fault and correct problem excessive load or poor insulation Dirty condenser Clean condenser Blocked filters Clean or replace filters Hot gas bypass valve stuck Check repair or replace Compressor valve leaking i Check high and low side pressures leaky valve will not be able to develop proper suction or discharge pressures See pages 46 and 47 Undersized TEV j See section l 9 for TEV selection Faulty EPR or pressure setting too high Replace EPR or readjust pressure setting where needed V 4 Unit Will Not Start Check pressure controls loads relays and capacitors Check power source Check circuit breaker Check fuses right size if blown find the cause Check thermostat contact made or loose wire V 5 Faulty Controls Check the control circuit transformer for size Check contacts Are they stuck open Check connections of terminals and contactors V 5 Causes of High Amperage Draw Probable Cause Remedy Reduce load Replace capacitor Correct voltage problem Rewire properly Replace compressor Replace contactor Rewire with proper size Voltage should not vary more than 396 between lines or call power company Excessive system load Defective capacitor High or low voltage Incorrect wiring Tight compressor Bu
88. compressor Check Manufacturer s specifications Replace heat exchanger Replace crankcase heater Clean evaporator coil Check for proper size and change if incorrect Check oil separator heater Check and replace if necessary Replace oil pump Clean oil pump screen Replace bearings pump or compressor Check high and low pressure control settings Check refrigerant charge Check for dirty condenser Replace burnt out condenser motors Adjust to correct voltage Replace control Replace overload protector Check wiring and correct 382 Different sizes of motors come with different ampere ratings The table on this page indicates the average expected ampere rating according to the horsepower of the unit Since all electrical components are selected by their voltage and amperage ratings the replacement part must have a rating that is equal to or greater than the actual full load amperage and locked rotor amperage of the motor Therefore when the compressor motor ratings cannot be determined by labeling or the wiring diagram this table can be used as a guide to determine the condition of a compressor motor Tight compressors and other factors see p 380 cause a higher than average amperage draw These factors should be carefully considered before condemning a compressor 5 Approximate 120 Volts AC 240 Volts AC g Horsepower Full
89. compressor running time is due to the increased pressure in the evaporator from overcharging The more refrigerant charged into the system the higher the head and back pressures go See the temperature pressure chart on page 133 2 Head and back pressures read higher than normal 3 High temperatures in the freezer and fresh food compartments The customer complaint here is that the unit does not get as cold as it used to This is true because the evaporator plates do not get as cold as they should 4 Suction line near the compressor sweats or frosts up 5 Compressor operating amperage goes too high Note the FLA run amperage on the nameplate example FLA 12 With the unit running close the jaws of the flux type ammeter around the wire going to the compressor run or common terminal If the meter reads 18 A for example the unit can be overcharged with refrigerant Look again at the section on Signs of Loss of Refrigerant item number 3 By using an ammeter it can be determined if the unit is overcharged with refrigerant fig 124 With the unit running and the ammeter placed around the run or common wire a high amperage reading indicates an overcharge too much refrigerant AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 183 1 Cage pd m adno ge gre 3 tener pre et eer cape APE aa IEP oC to LEEFT 1 theim See pug prerie pridd eel b kl 5 aN Ep
90. compressor connected to the evaporator is referred to as the low side meaning low pressure side and the side connected to the condenser is called the high side HEAT FLOWS FROM WARMER TO COOLER SUBSTANCES In nature there is actually no such thing as cold only the absence of heat In the illustration of the ice tray and the flame note the direction of heat transfer A Heat is transferred from the hand to the ice cubes causing the ice to melt B Heat is transferred from the flame to the hand causing the hand to get warm Just as water seeks its own level heat tends to equalize 10 11 12 13 14 15 16 17 18 19 20 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 11 A TEST OF KNOWLEDGE ON BASIC REFRIGERATION What are the other names for the suction and discharge sides of a compressor p 10 Which part of the unit radiates the heat absorbed by the refrigerant p 8 What causes the liquid refrigerant in the evaporator to vaporize pp 9 10 Why does vaporizing refrigerant in the evaporator make the freezing compartment cold pp 10 8 Explain the four essentials of refrigeration p 7 It is already known that water boils at 212 F at sea level At what temperature does refrigerant R 134A vaporize at sea level p 7 Never while the power supply is connected to the unit p 3 The side of the compressor connected to the evaporator is referred to asthe side
91. contactor Add stiffener to duct metal Check compressor shock mounts loose parts blower fan mounting etc Check plug and cord circuit breaker or fuse Fuse should be right capacity and proper time delay Be sure voltage is no more than 10 below that specified on nameplate AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 279 Problem and Possible Cause Remedy 3 Broken wire or bad component 3 Check wiring and connections check Compressor Runs But Fan Does Not 1 Fan motor burned out 2 Fan blade or blower wheel restricted 3 Broken wire or bad component Fan Runs But Compressor Does Not 1 Power supply faulty 2 Bad compressor or component Unit Runs But Does Not Cool 1 Compressor not pumping 2 Restricted airflow Unit Runs But Does Not Cool Enough 1 Restricted airflow Fan motor running slowly Voltage too low Poor seals Compressor not operating at full capacity Conditioned area too large Unit Short Cycles 1 Low supply voltage 2 Temperature set too high compressor capacitor switches relays overload protector and thermostat Check continuity in fan motor Check mounting or adjust blade Check wiring and connections fan capacitor defrost control and all switches Check for proper voltage to unit Check compressor start and run capacitors overload protector relays switches and wiring Check for restriction loss of Freon or lowered capa
92. contacts DTC open after a maximum of ten minutes every ninety minutes or the defrost thermostat DFT opens What contact s operate in the reversing valve solenoid RVS circuits and what is are the normal position s of the switch es DFR contact normally closed RVR contact normally open If the control relay CR in the 24 VAC circuit is energized and the compressor does not start name all the switches in the 220 VAC circuit responsible for this failure that should be checked CR HP LLP IT and C Name the switches in the defrost relay coil DFR circuit when the heat pump is in the cooling cycle Cool switch TC thermostat AUTO or ON switch and LP How does the first and second stage heating start The first stage heating starts when the TH 1 is manually closed on the wall thermostat The second stage begins when TH 2 on the wall thermostat senses the need for more heating and if ODT1 and or ODT2 thermostat closes which is are clipped to the outside coil the second stage heating will begin How many switches are there in the contactor relay Three two normally open and one normally closed Which switches on the wall thermostat are manually adjustable HEAT AUTO COOL ON OFF TH 1 and TC 348 24 25 The wall thermostat is set on the highest temperature the compressor is running but little heating is produced Which electrical components are most likely responsible ODT1 ODT2 HR 1 HR 2 reversi
93. cooling When C1 coil in the 115 volt circuit is activated it closes the C1 contacts energizing the compressor When OFC1 coil is activated it closes the OFC1 contacts to energize the outside number 1 fan motor OFM1 When OFC2 coil is activated it closes the contacts to condenser fan motor number 2 OFM2 When IFC coil is energized it closes the IFC contacts to energize the indoor fan motor AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 339 QUESTIONS AND ANSWERS ABOUT THE SCHEMATIC WIRING DIAGRAM ON PAGE 337 How many transformers are there in the entire circuit Two one transformer converts line voltage to 115 VAC the second one converts 115 VAC to 24 VAC What happens if the high pressure control is activated The compressor becomes energized What happens if fuse 4 burns out Nothing in the entire system will become energized What happens if transformer T2 burns out or becomes deactivated The internal fan relay and control relays 1 and 2 will become deactivated consequently the internal fan motor compressor and the condenser fan motors will become de energized What happens if one of the number 1 fuses burns out The compressor will become inoperative What happens if the relay coil CR1 burns out The compressor and outside fan motors 1 and 2 will become inoperative The crankcase heater will remain warm all the time On aservice call for not enough cooling the thermostat is adjusted to
94. cooling Unit will not start Faulty controls High amperage draw Loss of oil loss of oil pressure or oil pressure control trip out NOW PWNE CAUSES OF HIGH SUPERHEAT l 1 Flash Gas and High Superheat That portion of the liquid refrigerant which evaporates instantly flashes and turns into a vapor as it passes through the orifice of a refrigerant control is referred to as flash gas Since refrigerant controls TEVs AEVs are designed to control liquid and not gas flash gas reduces the efficiency of the control Flash gas at the inlet of the TEV obstructs the flow of liquid refrigerant and therefore starves the evaporator If flash gas enters the TEV the valve will operate inefficiently causing the system to lose some of its cooling efficiency and the superheat to increase Three probable causes of flash gas are a insufficient refrigerant charge b excessive pressure drop in liquid line or c a lack of positive head pressure control causes erratic head pressures The remedy for a and b is to add refrigerant to the system this raises head pressure For c install positive head pressure control valve as in figure 97d in which the valve stays closed until the pressure in the condenser builds up to a predetermined point before the refrigerant is permitted to leave If there is no sight glass in the liquid line at the TEV inlet a Flash gas can sometimes be detected by a characteristic steady whistling sound at th
95. de energize the circuits that are active Inr berry 3 LESER UOTA rei pre anas i NORMALLY CONTACTS Bior Son Winding n Motor Commen Winding Precim MAR another tarm lor Compressor Fun Wirdisg Relays have several contact points which energize or de energize different components in the unit The line voltage on each contact point can be 120 VAC 220 VAC or more Without the relay it would be very difficult to activate 244 de energize several switches simultaneously Relays usually operate on the same voltage as the wall thermostat CONTACTORS In an air conditioning system compressor and condenser fan motors are energized through a contactor a type of relay When the contactor coil is energized a magnetic field is created to overcome the spring tension separating the contacts points within the contactor assembly pulling the contacts together When these points come into contact with each other certain electrical circuits are completed such as the ones energizing the compressor and condenser fan motors When the contactor coil is de energized by an interruption through the wall thermostat the magnetic field is removed and the springs expand and separate the contacts See figs 152 152c and 153 In figures 152a and 152c note that the terminals in those contactors are normally open unless the thermostat closes the 24 VAC circuit to contactor coil in which case termi
96. decrease in current passing through the thermister to energize or de energize a circuit See fig 171 Figure 171 1 and 2 are the same low voltage wire lines that run through the thermostat 3 Thermister 4 Amplifier As temperature decreases resistance in the thermister increases stopping the current flow to the control relay and the cooling cycle ends 4 Thermostats that operate on the principle of changes in volume with changes of temperature such as the mercury type See fig 172 Am Figure 172 a 3 Heating cycle aercery tooling cree HEATING THERMOSTAT When room temperature rises mercury expands Because mercury is a liquid metal it is an excellent causing a change in the balance of the bulb As conductor of electricity the bulb tilts the mercury rolls away from the wire opening the circuit Mercury operated combination Heating and cooling thermostat Figure 172 shows a small pool of mercury in a glass bulb As the room temperature goes up Heating cycle lines 1 and 2 connected the volume of mercury increases causing the B Cooling cycle lines 1 and 3 connected balance to change and the bulb tilt connecting or disconnecting a circuit Bain cale Hanusml Difimrentia umbimg pasat Adj ume dey Bepew E Laver Bcraw A MERCURY OPERATED PRESSURE T CONTROL r amp leplatss Setting tall f 2 A capillary tube connects the pressure control Indicator 317 EE to the sealed s
97. evenly and in sequence Install cutter cutter nut and transport tube to evaporator flange with clamp Connect ice maker to condensing unit and check for operation INSTALLATION LOWER HOUSING and BEARING Figure 131g Courtesy of Wilshire Corp Schaumburg Illinois AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 197 GEARMOTOR ASSEMBLY Figure 131h 2 m zh Description Screw 8 32 x3 8 Motor shield End bell Motor screw Lock washer Gear motor stator Spring washer Washer Motor bearing upper Rotor assembly Seal motor Shoulder washer Motor bearing front Screw T O 6 32 x1 4 PHS Cable clamp 3 16 Manual T O Oiler assembly Gear case screw Cover Junction box screw Junction box cover Woodruff key Retainer ring Seal output Bearing shim Bearing cup Bearing cone Output shaft Output gear Bearing no 3 pinion Nylatron washer number 4 gear and 3 pinion assembly Bearing no 5 pinion Nylatron washer number 4 gear and 5 pinion assembly Gasket Case Spacer output shaft Lube quarts Cable Bushing WONDAUNBWNE Some ice machines are equipped with a low water safety control reed switch attached to the water reservoir to shut down unit if water level drops below bottom of reservoir It can be adjusted by bending the magnet arm number 3 as needed WATER LEVEL CONTROL ASSEMBLY B Description Reservoir assembly reservoir cover O ring and
98. figs 166 and 167 M urting hrrnews CENTRAL A DONO MIS THC ATIE A a M Angemaly ley a VR ee OE Lee LEUTE 258 As illustrated in figure 166 a wall thermostat consists of three parts 1 A back plate or sub base is fastened to the wall where the wires for the thermostat protrude see fig 167 2 A base is installed on the back plate with the wires running through a hole in the center and connected to the thermostat terminals on this base In some models the sub base and base are combined into a single unit 3 A cover is snapped onto the base It is very important to install the base absolutely level particularly in mercury bulb types as it will not function accurately if it is canted to one side or the other Auedwos 31139913 JO UOISIAIG sieSpoy eiluM Jo Asano The sub base on a mercury type thermostat must be level before completing installation Air Conditioner Wall Thermostat Wires coming through the sub base Wires connected to Figure 167 proper terminals SELECTING A GOOD LOCATION FOR INSTALLATION Thermostats should be installed on a solid inside wall at least 5 feet above the floor 1 5 meters It should not be installed where it is exposed to direct sunlight fireplaces lamps draft or any heat emitting source such as registers radiators or grilles The chosen wall should be unheated and more or less centrally located
99. for the oil pressure in the compressor Some units employ a low pressure control some employ a high pressure and some employ including the oil pressure control all three of the pressure controls are safety devices l LOW PRESSURE CONTROL The temperature in a commercial refrigeration unit is regulated by the low pressure control The low pressure control intersects the wire going into either the run or common terminal of the compressor There is a switch inside the control operated by a diaphragm This diaphragm is connected to the suction line by a length of small diameter tubing the sensing bulb through the low pressure access valve The pressure changes in the suction line are transmitted to the diaphragm through this line Some of these valves have a Y adapter so that both this sensing bulb and a gauge manifold can be connected When the pressure inside the suction line falls below a preset point it causes the diaphragm to flex turning off the electrical switch and disrupting Tories power to the compressor Figures 91 and 92 show a low pressure motor control This is a spring loaded device which is sensitive to the suction line pressure As the compressor runs the temperature and pressure in the evaporator are lowered As soon as y Bm e k ima m ir xa he min are AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 141 pressure drops to a g
100. freezer a glance at the chart will show you that the run terminal has a white wire connected to it the start terminal has a black wire and a red wire is connected to the common terminal Figure 40b STARTING A STUCK COMPRESSOR Occasionally after a long run in high ambient temperatures a compressor may become stuck and fail to start Reversing the rotation of the compressor by the following method may break it loose Prepare a single pole double throw SPDT switch two capacitors rated 130 50 mfd a line plug and three alligator clips Disconnect the unit from the power supply and remove all wires from the compressor terminals Hook up the reversing circuit as shown and plug the cord into a 115 VAC wall receptacle Operate the reversing switch by rocking it back and forth to alternately reverse the rotation causing the compressor to break loose Add SUPCO 88 additive to the system to prevent it from becoming stuck again AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 61 TYPES OF HERMETIC COMPRESSOR MOTORS AND HOW THEY ARE WIRED So far we have talked only about the kind Figure 41 of hermetic motors installed in residential units the split phase type These are called hermetic because they are mounted inside an airtight container with the compressor Basically there are four types of hermetic motors in commercial use today HERMETIC COMPRESSORS 1 Split phase hermetic motor as it has separate run and
101. from being flooded filled with refrigerant during the off cycle HOW TO SELECT AUTOMATIC EXPANSION VALVES Determine the following data They can be found on the unit nameplate Btu or tonnage rating of the unit System refrigerant Evaporator temperature or pressure Determine the expected evaporator temperature High side temperature or pressure Pressure drop across the valve These valves are set at a predetermined pressure and sealed with a lock nut Loosen nut to readjust Heat the screw with a heat gun to loosen for readjustment For servicing AEVs see the double temperature valve pages In this system the thermostat sensing bulb is attached to the outlet of the evaporator When sufficient drop in temperature is sensed by the bulb the contacts within the thermostat mechanism open causing power to the compressor to be disrupted and the cooling cycle stops see fig 117 Figure 1170 117 Bensing bulb SEHT il AS lngtzrrs bert vivus bobble deiecsion ler prec baj le een charging ary trevoareene Bright LED fgets eminas in sequesce do vhumby dipiamis moi bubi parsing Bet umen thee sete A typical comercial eefrigenatkon gni with a ihamora prid nn aima eae reo vae renirel Ee Ara of refrigerant Cis ol TI ba AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 169 LOW SIDE FLOAT SYSTEM Fig 109 Although the technical schools a
102. frost free refrigerator The evaporator is accessible from the front and the compressor condenser and the condenser fan are accessible when the rear cover panel is removed it is retained by a few screws The upper part of the drain system has a small heating element not shown to prevent restriction by an ice buildup during the defrost cycle The front grille is retained by screws or spring clips Condensation tray Condensation hose Defrost heater Condenser fan motor Compressor Grille Rear cover panel Evaporator fan motor Defrost thermostat 1 2 3 4 5 6 7 8 9 A TYPICAL FROST FREE REFRIGERATOR WITH A FREEZER ON TOP Figure 3 Various parts courtesy of Marvel Industries Division of Northland Corporation AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 15 The cabinet or body of the refrigerator contains and supports the evaporator condenser and the compressor The evaporator is located inside the freezer compartment where it absorbs heat from the food This heat is transferred to the condenser where it is radiated to the outside air The condenser is usually mounted at the back of the unit or in base of the cabinet next to the compressor figs 3 and 4 The air in a refrigeration unit is very dry because the moisture in the cabinet tends to collect and condense on the evaporator surface where the temperature is very low That is why food should be covered with a moisture proof cover to be k
103. gas Thus the unbalanced force due to the difference between discharge and suction pressures acting on the full end area of the main slide holds the slide in the down position as shown in figure 98i When the coil is energized see fig 98h the slide in the pilot solenoid valve raises now connecting ports D with B and A with S With the pilot solenoid so positioned the discharge pressure imposed on the top of the main slide area E flows through the pilot solenoid valve to the suction side of the system At the C end of the main slide high pressure discharge gas accumulates so as to increase the pressure An unbalanced force in an upward direction is again due to the difference between discharge and suction pressures acting on opposite ends of the main slide This unbalanced force moves the main slide to the up position as shown in figure 98h and the force unbalance across the area of the main slide holds the slide in the new position Depending on the design requirements of the manufacturer some reversing valves produce the cooling cycle when they are energized and some produce it when they are de energized When the solenoid in a reversing valve fails the valve will hold the unit only in the cycle it takes the unit to upon being energized Sometimes due to an internal short in the winding the solenoid loses the ability to pull all the way in or sticks in midposition in which case the unit neither heats nor cools In either case t
104. heat pumps as refrigerant flow changes in each mode Notice that the coil inside the house acts as an evaporator in the summer and a condenser in the winter the opposite being true in the case of the outside coil Note also that the reversing valve four way valve does not affect the flow of Freon into or out of the compressor it only creates a change in the direction of flow for each coil causing it to act as a condenser or evaporator as required to heat or cool 09 AJLA Asayino AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 267 NOTE Whether the unit is in the heating or in the cooling mode the flow of refrigerant to and from the compressor does not change Only the direction of refrigerant flow to the coils changes When the unit is in the heating mode the evaporator temperature should be set 20 F below the average ambient temperature for the most efficient operation This temperature difference is heat which is absorbed by the outside coil Bavarairg With the outside temperature at 50 F and the evaporator temperature set at 30 F the refrigerant condenses in the condenser at 110 F which is enough to warm the conditioned area Tnaids Cail Despite extremely cold weather when the unit is in the heating mode heat can always be extracted as long as the evaporator temperature is set below the outside ambient temperature tenia Ped 1 The teenie eee
105. in commercial units the problem can also be due to a defective capacitor in which case the capacitor will have to be checked See the pages about Capacitors Figure 57 Asi CD 8 PO B rir Shroud nut 15 Fyne Fan shaft nut Spacer Fan motor Sht Mtl Screws Line Bracket Washer Courtesy of Marvel Industries Division of Northland Corporation Figure 58 FAN BRACKET KIT This condenser fan bracket is a popular style for residential units The ring is mounted on the back of the fan motor and the legs are fastened to the fan shroud a Sometimes the blade must be removed before removing the motor Hold the blade with one hand and with a nut driver or a pair of pliers remove the stamped nut and gently remove the blade Note the pitch of the blade If it is remounted backward on the new motor it will move the air in the wrong direction b Removethe motor and its bracket by removing the screws connecting the bracket to the refrigeration unit c Remove the bracket from the defective motor see fig 58 d Mount the bracket to the new motor in the same location it was on the old motor e Mount the fan blade to the new motor ensuring that its pitch is in the same direction as on the old motor f Install the assembly reconnect the wires and replace the cover panel When replacing condenser or evaporator fan motors in commercial refrigeration units al
106. in liquid state The sensing bulb is installed at the outlet of the evaporator If all of the refrigerant becomes superheated before leaving the evaporator the bulb senses the higher temperatures and transmits signals to the valve for more refrigerant The valve opens wider and admits more refrigerant to a point where all of the refrigerant within the evaporator coil will not get a chance to boil off and become superheated and a portion of the refrigerant remains in the liquid state while leaving the evaporator at which time the bulb senses the lowered temperatures due to the passage of this liquid refrigerant and transmits a signal to the valve to limit the flow of refrigerant into the evaporator This cycle continues as long as the unit runs Since only superheated refrigerant with very little heat absorbing capacity should reach the TEV sensing bulb the temperature of the bulb is always above the actual evaporator temperature This temperature difference is called superheat The best way to adjust this type of valve is to do it by superheat adjustment Here is a general rule of thumb for superheat adjustment A GENERAL RULE OF THUMB FOR SUPERHEAT ADJUSTMENT 1 10 F to 12 F Superheat for high temperature evaporators 30 F evaporators 2 5 F to 10 F Superheat for medium temperature evaporators to 30 F evaporators 3 2 F to 5 F Superheat for low temperature evaporators 0 F and below evaporators Turn t
107. in the circuit being checked USING A VOLTMETER A voltmeter registers the potential difference voltage In figure 182 if the two voltmeter probes were to touch the H or N terminal of the 110 VAC receptacle no voltage would be registered on the meter But if one probe were to touch the H and the other one touch the N terminal the meter would register a voltage reading because of the existence of a potential difference between these two terminals In wiring diagrams the two terminals are represented as L1 the hot terminal and L2 the neutral terminal in a 110 VAC circuit and another hot terminal a 220 VAC receptacle Knowing this simple principle is essential in using a voltmeter in any circuit In figure 179 if L1 and L2 were plugged in the switch closed turned on and the two voltmeter probes touched the two power terminals on the switch the meter would register O volts It would be just like the two probes were touching only the L1 side of the receptacle As soon as the switch were opened turned off the meter would register a voltage reading because the open switch would separate the L1 and L2 sides of the circuit and a potential difference would be detected Any open switch or load separates the line In the case of a good fuse if the voltmeter probes were to touch the two terminals a zero voltage reading would be registered But if the fuse were blown burnt out the meter would register a voltage reading because of th
108. inches of vacuum within 60 seconds or so At this point turn off the compressor If within this period the reading on the compound guage begins to move toward zero the compressor has an internal lear Bad Gasket O Ring Bearing etc and must be replaced only bolted type compressor are repairable Figs 119 120 if the compound guage reading never reaches 28 or 29 of vacuum while running it has lost its pumping ability and must be replaced An efficient compressor must reach about 29 or vacuum an maintain the level of vacuum after it is turned off Residential refrigerators and freezers that do not come with access valves can be tested for efficiency by pinching off the liquid line see Figure 45g by using a pinch off tool and by installing a tap value see Fig 45f on the suction line before you follow the same procedure 52 TESTING THE COMPRESSOR Compressors become inoperative through either a mechanical or an electrical failure Before beginning a compressor test check the power supply to see if low voltage is the problem The voltage must be high enough to bring the initial speed up to 75 of its normal revolution per minute rpm to allow the run winding to take over If after start up this initial speed is never reached the run winding will never engage causing the start winding to overheat in a few seconds When the overload protector senses the high amperage heat it shuts off the power to the compressor When the co
109. is 212 F at sea level At this point the water is still in a liquid state As the water is further heated the temperature remains at 212 F until an additional 970 Btu are applied At that time the water begins to vaporize even though the temperature does not increase In other words water boils at 212 F and vaporizes at 212 F plus 970 Btu see fig 133 The additional 970 Btu applied to the heated water to change its state from liquid to vapor is referred to as latent heat Latent heat even though not measurable by a thermometer makes the change from one state to another possible Conversely should the vapor give up 970 Btu it would change to a liquid state without changing its temperature 228 The process whereby latent heat is absorbed by the evaporator and radiated through the condenser is the principle of modern refrigeration and air conditioning To change liquid refrigerant to its vapor state when it is forced into the low pressure environment in the evaporator it must absorb the needed latent heat from the environment around the evaporator When the environment around the evaporator loses its heat to the vaporizing refrigerant through the walls of the evaporator coil it becomes cooler When the vapor refrigerant gives up its latent heat going through the condenser it changes back to its liquid state This latent heat is then radiated into the surrounding atmosphere In an air conditioner inside air is d
110. is needed is the name and model number of the unit a Install a piercing valve on the compressor suction side and leave it closed 116 b Connect the piercing valve to the compound gauge manifold and the middle line in the manifold to the refrigerant tank as shown in figure 82 Leave all valves closed c Turnon the unit d Turnonthe piercing valve the compound gauge valve and the refrigerant tank Dariy m4 Bis M LErparatian THARI hG THE LO thee rendo W e Keeping a hand on the compound gauge valve watch the compound gauge and every few seconds turn off the valve and check the gauge for the desired low side pressure f Uponreachingthe correct low side pressure turn off the manifold valve the piercing valve and the refrigerant tank valve g Disconnectthe lines puta little Teflon tape on the threads of the piercing valve and replace its cap Make it a habit of running an electronic leak detector over all the tubing and valves in the system after recharging Make certain there is no refrigerant leakage A mixture of one half cup of liquid soap to one gallon of water can also be used as a leak detector when a leak is suspected in a particular location Simply apply the mixture to the tubing or the connections and watch for bubbling AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 117 Serii blanket kar a seiren fumi The heat kom the blanket Ais sn the Reo tank
111. most cases after the spinner touches the tubing about six and a half turns should form the flare Do the same with the other piece of tubing that is to be joined Don t forget to put the flare nut on first Use Pipetite a pipe fitting compound or a short length of Teflon tape around the male threads to establish an airtight seal Teflon is the better of the two If the compound is used be sure to apply it sparingly to prevent it from getting into the lines whenthe flare nuts are connected NOTE Connections made in plastic tubing such as a water supply to an ice maker use compression type fittings since plastic cannot be flared AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY Put nut on tubing and insert tubing into correct size collar in anvil block A STEP BY STEP GUIDE TO MAKING FLARE CONNECTION Turn spinner about six and a half turns Figure 26 Remove spinner and tubing from anvil block Tubing can now be connected to a male counterpart Use Teflon tape to ensure an airtight seal 4 Urkon Coapresnicna Compression 4 imion Unien Taa Elbeni Threaded Reducing Pipe ta m Compremakaon ry tea asa enim Collar 4 Wut variety of compression fittings used in refrigeration and air conditioning To prevent possible leaks do not overtighten nuts and couplings Figure 26a 44 BENDING TUBING Do not attempt to bend tubing by hand or around Figure 27 a pipe or pole
112. moving up and down ina cylinder Instead of relying on exploding and expanding gas to drive the piston the piston is powered by an electric motor As the piston moves downward or backward the inlet valve opens and vapor is drawn in from the evaporator When the piston starts up toward the top or forward the inlet valve closes and the gas is compressed thereby raising its temperature Before the piston reaches the top or its most forward position the discharge valve opens and allows the gas to be propelled into the condenser see fig 28 They are used in commercial and residential units light and heavy applications These compressors can be hermetic or externally driven Figure 28 ad ve THE PRINCIPLE OF THE RECIPROCATING COMPRESSOR Asthe piston moves down cold vapor is drawn in from the evaporator As the piston moves upward the vapor is compressed and converted to a hot gas which is then forced into the condenser fig 28a In a reciprocating hermetic compressor the circular motion of the rotor causes a back and forth movement of the piston Right A motor stator B motor rotor C compressor cylinder D compressor piston E connecting rod F compressor winding G compressorterminals under a plastic cover H compressor housing weld I compressor suction tube J compressor discharge tube K compressor housing Courtesy of Tecumseh Products Company AIR CONDITIONING AND REFRIGERAT
113. must be filtered prior to entry to the valve to prevent internal damage VALVE OPERATING PRESSURE ADJUSTMENT This pressure adjustment is easily and quickly made by turning the adjusting stem with a standard service wrench To increase flow decrease head pressure turn stem counterclockwise To decrease flow increase head pressure turn stem clockwise Actual operating condenser pressure is as much as 25 30 psi above the opening pressure Low suction pressures or high water pressures tend to lower condenser pressure High suction pressures or low water pressures tend to raise condenser pressure Generally it is better to determine the maximum summer temperature of the water to be used and adjust the valve accordingly rather than adjusting it for each season See minimum recommended valve opening pressures psi on page 392 392 WATER VALVE ADJUSTMENT Referring to the chart you will find the corresponding head pressures expected for different water temperatures Adjust the valve adjusting screw to the desired head pressure and let it run for some time It should automatically when the head pressure reaches the point indicated on the chart Use athermometer to check the water temperature and a compound gauge to check the head pressure WATER TEMPERATURE F REFRIGERANT 50 55 60 65 70 75 80 85 90 95 0 HEAD PRESSURE TABLE HEAD PRESSURE psi FOR WATER TEMPERATURE R 12 56 62 68 74 80
114. of refrigerant into the evaporator and counterclockwise to increase the flow Turn this valve stem only one fourth turn at a time then HIGH SIDE wait for about five minutes for 110 a partial frost pattern to appear on the evaporator coil A hissing sound from the evaporator while the 160 unit is turned on indicates a starved evaporator In this case turn the stem counterclockwise as described above Bulb Force F1 Diaphragm Bpring Force Remote Bulb Figure 110a Courtesy of Eaton Corporation Appliance and Specialty Controls Division The Simple Operation of the Thermostatic Expansion Valve Reiter Figure 110b A Fi Evaporator Force Fl Bpring Force urea CLnksieg A TEV is designed to control evaporator superheat by the reaction of the three forces on the diaphragm Espansion Valve TEscmiWwur Ewa atur Install the expansion valve as close as Compressor possible to the Cotes evaporator inlet Figure 110c Capillary On replacement of any valve it is most important to obtain an exact duplicate one with the same specifications Just as containers for different types of refrigerant are color coded the majority of TEVs are color coded indicating the type of refrigerant they can handle If they are not color coded they have a label or tag giving the specifications of the unit for which
115. potential shock hazard Proceed cautiously Be sure not to touch any wire without its insulation If the insulation is cracked or frayed or if for any reason it does not seem 98 right unplug the unit put the meter in place and then reconnect the unit and wait for about three minutes until the compressor starts then proceed STUDY THE SECTION ON BASIC ELECTRICITY BEFORE CONDUCTING THIS TEST Mullion Kowter Figure 72 o Ureerload Promectes A Three terminal Door Switch 1and 2 Cabinet light 3 Ground A Four Terminal Door Switch TESTING THE DEFROST HEATER 1 Check the electrical diagram schematic of the unit refer to figs 54c through 541 or the chapter about Reading Electrical Diagrams to determine which one of the timer terminals is wired into the defrost heater 2 Using a screwdriver turn the knob on the back of the timer until a click is heard and the compressor stops running 3 Place the clamp of the clamp on ammeter around the proper wire and check the reading The meter should register about 5 A If the ammeter registers a considerably lower reading such as 1 or 2 A the defrost system must be inoperative Check the defrost bimetal and the defrost heater and replace the defective part Common Cabinet light Evaporator fan Ground ad TYPICAL DOOR SWITCHES Sometimes due to a defective light switch the light in the fresh food compartment will not
116. pressure reading atthat added temperature for the type of refrigerant used in the unit This figure indicates the expected head pressure in the unit For water cooled condensers the head pressures should be calculated by adding 20 to the exhaust water temperature See the section on Water Cooled Condensers EXAMPLE Suppose there is a commercial central air conditioning unit using R 22 operating in an ambient temperature of 90 F Assume also that this is a new unit with no malfunctioning parts What head pressure should you expect to read on the high pressure gauge For the answer add 30 F to the ambient temperature 90 30 120 F find 120 F on the chart and read across to the R 22 column Hence 259 9 Ib in will be the expected high side pressure If the system is overcharged if the condenser is dirty and or linted if there is a slow or inoperative condenser fan or if there is a restriction in the system the head pressure increases dramatically causing a higher than normal head pressure A temperature pressure chart should always be carried with you on service calls The amount and type of refrigerant used in the unit can be determined by the unit nameplate PROBLEM Determine the head and the back low side pressures of an ice cream freezer with a cabinet temperature of 20 F using refrigerant 502 The unit operates in a room with an ambient temperature of 80 F SOLUTION The evaporator temperature must be adjusted to 20
117. s Blower wheel slips on shaft Refrigerant low as shown by low amperage evaporator not cold or large portion of condenser cool 8 Lack of insulation on ducts 9 Air leaks in ducts 10 Insufficient air from evaporator Compressor Does Not Shut Off 1 Dirty condenser 2 Unit too small for structure 3 Low charge of refrigerant 4 Control does not shut off Unit Is Excessively Noisy 1 Air noise in duct work 2 Mechanical noise in unit Unit Does Not Run 1 No power to unit 2 Low voltage Remedy 6 Check for proper voltage Allow enough time for overload to reset If condenser pressure is normal but compressor draws more than rated amperage compressor is defective Check control switches refer to nos 7 and 8 on page 277 Adjust to desired temperature Relocate thermostat away from drafts out of direct sunlight etc Check cause Clean condenser and or evaporator Clean or replace Check and tighten Allen screw Recharge after checking for restriction in capillary tube strainers TEV and filter drier Amperage should not be lower than FLA shown on condensing unit nameplate Replace loose or missing insulation Check and repair Make sure duct dampers are open duct runs are not too long or too small Adjust blower speed Inspect and clean Check for required cooling capacity Add refrigerant after checking for leaks and refrigerant restriction Check thermostat and
118. separator must be drained too Measure the total volume of oil drained from the system and recharge system with equal amount of alkylbenzene lubricant Reinstall compressor if removed Replace filter drier with one suitable for SUVA MP refrigerant blends Using a vacuum pump evacuate system to 29 9 inHg vacuum Using normal service practices check system for leaks check with manufacturers of your existing electronic leak detector for its sensitivity to SUVA MP refrigerant blends If any leak detected seal leak and re evacuate system Charge system with SUVA MP 39 or SUVA MP 66 Only liquid refrigerant must be removed from refrigerant cylinder To prevent any damage to the compressor due to liquid refrigerant entry you may screw an insta charge restrictor adapter on the valve on the refrigerant tank to instantly convert liquid refrigerant to saturated vapor before it reaches the system see fig 220 Begin charging 70 to 75 by weight of original R 12 charge Begin charging 100 by weight of original R 500 charge AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 405 9 Run equipment and adjust charge until optimum operating conditions are reached only liquid refrigerant must be removed from refrigerant cylinder If more charge is required add refrigerant to the system in increments of 3 to 5 of original R 12 or R 500 charge SUVA 134A REFRIGERANT It is the environmentally acceptable alternative replacement for R 12 us
119. service valve p 156 Whatis the purpose of a reversing valve p 156 10 How does a bulb type expansion valve work pp 159 160 11 What is the function of a thermistor p 165 12 How does an automatic expansion valve differ from a capillary tube p 167 13 What is a patented tube p 65 14 How would the length of a 0 042 inch capillary tube be determined for a 1 4 hp low temperature compressor p 66 15 What symptoms indicate a loss of refrigerant pp 176 177 16 What symptoms indicate a restriction in the sealed system pp 176 177 17 What causes high head pressure p 180 18 Would the symptoms of an overcharged system be the same or different from a system with a dirty condenser pp 181 182 19 When is heat applied to an evaporator of an ice machine p 187 20 Do ice flakers use a defrosting method in the harvest cycle p 189 21 What are the symptoms of an open bin thermostat in an ice machine p 191 22 When is power to the ice cutter grid shut off p 182 23 What would happen in an ice maker if the bin thermostat contacts were to stick in the closed position p 198 24 What indicates a bad expansion valve in an ice machine pp 199 200 25 What problem would an incorrectly wired relay cause p 201 26 How is calcium removed from evaporator plates p 202 27 Describe the operation of a heat exchanger in a water fountain p 203 28 What would be a symptom of a dirty c
120. stay off overnight to become completely defrosted Or for faster results a pan of hot water is placed in the freezer while the unit is turned off for a few hours The freezer temperature ranges between 5 F and 15 F and the temperature in the fresh food compartment ranges between 38 F to 45 F Normal low side pressure in manual defrost units varies between 10 15 psi Cycle defrost refrigerators are less troublesome than the manually defrosted units but 18 they are not as sophisticated as the fully automatic units In the cycle defrost type defrosting occurs each time the thermostat becomes satisfied An electric heating element attached to the extension of the evaporator in the fresh food compartment fresh food evaporator becomes energized to ensure thorough de icing of the fresh food evaporator in the off cycle see fig 5 A TYPICAL WIRING METHOD OF COMMERCIAL OR RESIDENTIAL Figure FROST FREE REFRIGERATOR OR FREEZER A COMMERCIAL FOOD PREPARATION REFRIGERATOR Def amiat One or more fans move air through the evaporator coil Courtesy of Beverage Air THENE Note the pattern of air circulation in a _ frost free refrigerator with the evaporator on the top a frost free freezer and upper left a commercial refrigerator Figure 7 1 Air circulation pattern in a frost free refrigerator 2 Air circulation pattern in an upright freezer Cycle defrost refrigerat
121. temperature types which produce temperatures down to about 0 F medium temperature types which produce temperatures of about O F to 10 F and low temperature models which produce temperatures below 10 F A capillary tube sizing gauge can be purchased Figure 45c Patented tubes can be used for capillary tube replacement Figure 45d CAPILLARY TUBE GAUGE from a major local refrigeration supply house This is a tool similar in appearance to a spark plug gapping tool used by auto mechanics It consists of a number of different sized wires to measure the inside diameter of capillary tubes see fig 45d See the chart on the next page for the required length of tubing based on its inside diameter the horsepower and temperature rating of the compressor When handling capillary tubes it is important to remember that 1 capillary tubes are connected to the sealed system mostly by silver brazing a flared connection is seldom used and 2 since capillary tubes are too small in diameter to be cut with a tubing cutter the usual practice is to score them with the edge of a file It is then bent carefully until it breaks 66 Figure 45 CAPILLARY TUBE LENGTH IN FEET hp COMPRESSOR TEMPERATURE ID 0 031 0 036 Medium Low High Medium Low High Medium Low High Medium Low 0 042 0 049 0 055 0 065 To silver braze a small capillary tube to a large tubing place the small tube at least two in
122. terminal in the wall receptacle and flows into the timer through timer terminal 1 It flows to a defrost heater through a defrost bimetal and also to a drain heater then back to L2 the neutral terminal in the wall receptacle to complete its circuit AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 313 Lime w Enurgizad Line Energiced Interior Light EI NE Ti Comm Defrost Bimetal Dafrant Beater 192 Drain Heater _ Thereostatl Probecbar Falay Evaporator Fan Figure 184c AUTOMATIC DEFROST REFRIGERATOR IN THE COOLING CYCLE The timer cam shifts to position number 4 and takes the unit into the cooling cycle and stays in this cycle for six eight or twelve hours depending upon the kind of timer used Pay close attention to the direction of the flow of current It starts from L1 the hot terminal in the wall receptacle flows into the timer and through timer terminal 4 to the compressor evaporator and condenser fan motors through the thermostat and then back to L2 the neutral terminal of the wall receptacle to complete its circuit 314 12 Volts 60 tyele I Door Switch Compressor Wn ary Thermoak Protector Evaparatar Heater EW GOD Ohms BraiB Beater 1550 Ohma Aullies Seater 14 1538 Chea W Coan Heater 17 98 800 Ohmm Figure 185a A TYPICAL SCHEMATIC WIRING DIAGRAM THAT COMES WITH A CYCLE DEFROST TYP
123. the armature to its upper disconnect position Compare this schematic with figure 163 on page 254 to get a better understanding AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 331 Turning on air conditioning units requires closing or opening many different electrical circuits to operate the unit To make this possible a control relay which operates on low voltage or sometimes on line voltage depending on the unit becomes energized causing its contacts to snap open or close thus energizing or de energizing various circuits See fig 151 The main circuits run through the relay contacts When the relay coil is energized it creates a magnetic field moving an armature which in turn shifts the contact points As these points come into contact or separate from one another by the movement of the armature individual circuits are interrupted or connected In other words a relay that can operate on low voltage power controls other circuits that are connected to higher voltage lines In the schematic wiring diagrams each contact of a relay is shown on the line voltage circuits which is intersected by that particular contact The relay contacts that are normally open close when being energized and those that are normally closed open when energized Refer to figures 194a through 194c Note the representation of relay contacts on the schematic wiring diagram Three phase motor protector It protects the compressor by shuttin
124. the diagram the lines carrying power to the compressor condenser fans and the internal fan motor evaporator fan run through a set of fuses and relay contacts The wiring system of the unit includes two transformers T1 and T2 Transformer T1 reduces the line voltage to 115 VAC and transformer T2 reduces that 115 VAC to 24 VAC The 24 volt circuit runs through the wall thermostat and a set of relay coils IFR CR1 and CR2 The components in the 24 VAC circuit control the 115 VAC circuit and the coils in the 115 VAC circuit control the operation of the compressor OFM1 OFM2 and the IFM If the head pressure drops to an unacceptable level due to cooler ambient temperatures the fan control pressure switch FCPS connected to the liquid line de energizes the condenser fan motor 2 OFM2 until the head pressure reaches a proper level The liquid line solenoid control LLS is connected to the evaporator outlet When it senses the evaporator pressure has dropped below a preset level it automatically energizes solenoid valve LLS which is installed on the liquid line thereby putting more refrigerant into the evaporator through auxiliary capillary tubes which bypass the TEV This will increase the pressure in the evaporator LLS is energized when CR2 closes TC1 and TC2 are switches mercury or spring operated or solid state are located inside the wall thermostat and control the two stages of cooling The TC2 switch activates the second stage
125. the thermostat is in the on and heat position it closes the 24 40 volt circuit to a heating relay causing a gas valve in the furnace compartment to become energized to open the flow of natural gas heating the conditioned area until the temperature sensed by the wall thermostat rises above a preset point see fig 156 and 162 In the warm seasons when the wall thermostat is set in the On and Cool position it closes the 24 40 volt circuit to the contactor coil energizing the compressor and the condenser fan causing the unit to cool Once the conditioned area reaches a predetermined temperature the thermostat opens the 24 40 volt circuit and the contactor coil becomes de energized and consequently power to the compressor and the condenser fan motors is interrupted Each wire in the wall thermostat is color coded and fastened to its designated terminal There is more detail about this on the pages about wall thermostats Inside the furnace compartment air handler a fan relay is placed in series with the fan circuit to start the evaporator blower fan when the thermostat closes the 24 volt circuit 254 A condensing unit is hooked up to 220 VAC circuit breaker installed next to it This makes it possible to disconnect power to the unit if needed Figure 163 0 09 SL OY iS Outdoor breaker panel Fused on off switch Condensing unit Wall thermostat Suction line Liquid line A coil inside Condensate water drain
126. there power available at the No power unit Are circuit breakers on And Bad bin thermostat gt Overload or relay defective are fuses OK Bad compressor 2 15 the problem caused by poor or Pressure control defective Defective master switch no refrigeration 3 Is there a water problem Is enough water getting into the ice machine Check the water valve solenoid water float and hoses for corrosion and deterioration Check for clogged water lines or filters and clean as necessary 4 15 the problem due to faulty controls such as a thermostat or solenoid valve Follow these procedures to quickly troubleshoot the problem Allow the unit to run for at least one cycle to see what happens If it continues building ice and never goes into the harvest cycle the problem is probably the thermostat or the molds have become too dirty and have lost their smoothness due to mineral buildup on the evaporator plate In this case clean the surfaces carefully and thoroughly using the manufacturer s recommended cleaning agents If the smoothness cannot be restored try spraying them with Teflon or replacing the evaporator plate if necessary Very often the master water valve sometimes located under a kitchen sink may have been inadvertently shut off by the owner or an employee Check to see if it is turned on and that the water float is in good working condition Figure 131 shows a wiring diagram of a typical ice machine A UIUSTIBI
127. they are suited The label shows the type of refrigerant and the tonnage of the unit Valves can be obtained with flared or brazed connections For those with flared connections be sure they are fastened tight enough to prevent Freon leakage but not too tight to damage the flare Use Teflon tape on these connections The bulb is attached to the evaporator outlet by a couple of screws It is important not to change the location of this bulb when a new one is installed See figs 110c through 110e Be sure not to bend the bulb line sharply during installation otherwise it may inhibit the free flow of refrigerant The bulb should be seated on a straight section of the last portion of the evaporator line not on a curve AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 161 The temperature ona curve is slightly different because the pressure produced at that particular point is different and produces a false temperature With the unit running liquid refrigerant passes through the TEV and gets into the evaporator where it immediately absorbs heat and boils off becomes superheated vapor Superheated refrigerant due to the absorption of heat loses a great deal of its cooling capacity A properly adjusted valve admits the correct amount of liquid refrigerant into the evaporator to produce the desired evaporator temperature by absorbing heat and becoming superheated and the least amount of refrigerant leave the evaporator
128. through their suction or discharge line Open drive and semihermetic compressors are equipped with an oil drain hole In large commercial systems lubricant present in the accumulator s and oil separator s must also be drained Charge compressor with an equal volume of lubricant compatible with SUVA HP 80 or HP 81 Reinstall compressor if removed Change filter drier to one suitable for use with HP 80 or 81 Evacuate system with a vacuum pump Vacuum to 29 9 inHg Using normal service practices check system for leaks Check with the manufacturer of your detector for its sensitivity to HP 80 and HP 81 8 Charge system to 9096 by weight of the original charge with SUVA HP 80 or 81 with the refrigerant cylinder in an upright position Only liquid refrigerant should be removed from the cylinder The initial charge should be added to the system with the compressor turned off 9 Run equipment and adjust charge to achieve optimum operating conditions If more charge is needed add more SUVA HP 80 or 81 in small amounts from the cylinder d p SUVA HP 80 and SUVA HP 81 come in 15 Ib 30 Ib and 123 Ib cylinders that are color coded light brown SUVA HP 62 REFRIGERANT It is an environmentally acceptable alternative for 502 and formulated for use in new commercial refrigeration equipment producing medium and low temperatures such as vending machines ice machines food service and transport SUVA HP 62 r
129. to collect all foreign matter to keep it from entering the compressor that may cause internal damage It should always be installed after a compressor burnout Larger commercial systems use bolted type suction line filter driers to allow a quick replacement of the filter element They are also equipped with an access valve through which pressure is checked with the compressor running and then compared with the compressor suction pressure If the gauge registers a pressure drop of more than 2 psi the filter drier should be replaced A liquid line filter drier used in residential and small commercial units A liquid line filter drier equipped with an access valve used in residential and small commercial units E and F are installed in systems using a capillary tube Courtesy of Eaton Corporation Controls Division 110 THE FOUR METHODS OF CHARGING A REFRIGERATION UNIT x Charging by ammeter reading x Charging by the amount of refrigerant shown on the nameplate critical charge Charging by the evaporator frost pattern x Charging by the low side gauge pressure CHARGING THE SYSTEM BY AMMETER READING When measuring the charge by an ammeter bear in mind that with the unit running the more refrigerant is charged into the unit the higher the ammeter will read and vice versa If the unit is operating properly any reading other than the FLA amperage which is printed on the nameplate of the unit will either be an underch
130. turn off when the door is closed The heat created by the bulb inside the unit cabinet will not let the cabinet temperature drop low enough to satisfy the thermostat When this happens the compressor never shuts off Check the door switch by opening the door and pushing the light switch If the light stays on replace the light switch CHECKING A DOOR GASKET A leaky door gasket allows outside air to penetrate the cold compartment and cause frost to collect on the evaporator coil and longer running time In the fresh food compartment moisture appears on the walls and floor AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 99 1 2 and 4 Compression type gaskets 3 Magnetic type gasket Gaskets for residential units are purchased through suppliers of those units Commercial gaskets can be purchased from commercial refrigeration hardware supply houses They can be ready made or purchased by the yard In some commercial wk ES TYPES OF units gaskets are secured by cement DOCE GASKETS 7 DOOR GASKET Gaskets are installed to prevent air from getting into the cabinet Magnetic and compression gaskets are the two types used in refrigerators and freezers today They are secured to the door by screws or sometimes by cone or dart clips in chest type freezers that pass through the gaskets the door liner then threaded into the door panel In some models retainer strips are used In which case the screws pass through the ga
131. use wrenches that fit the nut or bolt screwdrivers that fit the slot in the screw head etc The wrong size wrench does not fit or it is slightly too large causes the edges of the nut or bolt to become rounded Too small of a screwdriver causes the blade to twist or shave the edges of the screw slot The proper size screwdriver allows the application of more torque with less effort When turning a nut or bolt draw the wrench toward you rather than pushing it away While pushing if the wrench slips it may cause a hand injury Never try to drive a wrench with a hammer or use a cheater bar a short length of pipe on the shaft as it may damage the tool the nut or bolt or cause an injury If more torque is necessary use a longer wrench or a loosening agent such as Screw Loose Make it a habit to remove watches and rings and secure any loose clothing before beginning to work Wearing safety toe shoes shoes with a hard steel cap in the toe is also a good idea BASIC REFRIGERATION MOST IMPORTANT KEEP THE INFORMATION ON THIS PAGE IN MIND AS YOU PROCEED WITH THIS COURSE DISPLACING HEAT BY VAPORIZING REFRIGERANT Different liquids boil at different temperatures Some need a great deal of heat to reach their boiling point to vaporize while others require very little When speaking of boiling a liquid we immediately think of heating water in a pan ona stove and watching it bubble The fact is that the boiling points o
132. valve must be used on any system in excess of three tons regardless Figure 110h shows how to measure superheat of application in systems using a TEV with an external equalizer AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 165 SOLID STATE THERMOSTATIC EXPANSION VALVES Electric Valves Figures 107 107a and 111 show a solid state type of TEV This type of valve can be used on any system Unlike the bulb type TEV the electric valve eliminates the problem of placement of the sensing bulb The electric valve is operated by and responds to low voltage electricity Its operation is simple and easy to understand Tha salve alve FEER Aum D ibed anes Ligeia rw 1 font La Pad inte Tabar Ls 1 Tri r 2 Az q a gt EAM contacts t la 4 at the I2 Figure 112 r incre ad o emm l a an t pa leg HE eee oe 3l l F jr Tharmiebzr T aor rn E Fipe 111 r TW Iz E feet F i k LL 7 An iliuatratios D ri m E H hock ol an el rtric 5 ML Beli ate TET Re S A liquid sensing thermistor see fig 112 is installed in the suction line at the outlet of the evaporator where a complete change of refrigerant state from liquid to gas occurs
133. very simple Considerable effort has been made to keep the text clear and concise Study each page until it is clear before going on to the next By studying carefully and paying attention to all the details the technician will be able to provide his customers with high quality service This is a very profitable business and the market is as big as the world Information gained and used from this course is probably the best gift anyone can give his or her loved ones truly a gift to last a lifetime The average person can develop this into a very lucrative business during his first year of operation This book is dedicated to those who are serious about succeeding in this profession but cannot afford the time or expense of a full time formal training course RULES FOR PERSONAL SAFETY WARNING DISCONNECT POWER SUPPLY BEFORE BEGINNING ANY TYPE 10 11 OF SERVICING TO AVOID INJURY OR POSSIBLE DEATH FROM ELECTRICAL SHOCK Always wear safety goggles or glasses when working on refrigeration or air conditioning units where there is danger of flying particles from compressed gases Never breathe refrigerant fumes of any kind Always wear a gas mask when working in a refrigerant laden atmosphere or near brazing fumes Do not expose yourself to electrical shocks Do not work on electrical circuits in moist or wet areas and always keep open electrical terminals covered with an insulating material Make sure there is an adequate and
134. waterborne minerals the system must be thoroughly flushed with clear water prior to putting the fountain back in service Even in small quantities these chemicals can cause gastrointestinal injury or other problems if swallowed AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 207 TROUBLESHOOTING BY TOUCH This method of troubleshooting refrigeration problems is very quick and easy and practiced by many technicians in the industry As refrigerant circulates in the sealed system under different pressures various temperatures are produced in its path The hand felt temperature of the components and tubing can be a good indication of the internal condition of the unit when compared with the standard expected temperatures when the unit operates in an ambient temperature between 75 F and 85 F Compressor A warm to very warm compressor is normal A hot or very hot compressor indicates a continuous excessive load or running time Evaporator f it produces temperatures below 32 F a frost pattern is observed A restriction or a shortage of refrigerant is indicated by a below average frost line An inefficient compressor may show an above average frost line Suction line temperature at the compressor should feel cool Condenser The discharge line from the compressor should be very hot The top of the condenser should feel very hot to the touch It should gradually lose that heat as your hand passes down the surface to feel warm at the b
135. when humidity lowers Check door gasket adjust or replace as necessary 122 NAMEPLATE LOCATION UNIT IDENTIFICATION PLATE The nameplate can be a piece of metal riveted to the body of a refrigeration unit a thin metal label with a sticky back or a piece of paper glued to the unit In smaller refrigerators and freezers it is sometimes inside at the bottom of the cabinet under or next to the crisper drawers or seldom in the back of the unit In side by side units it is normally hidden behind the kick panel grille or toe plate and can be easily found when the panel is removed In commercial units it is most commonly riveted to the side wall inside the cabinet or somewhere close to the compressor In window air conditioners it can be found under the front panel In central air conditioners it is attached to the condensing unit or to the compressor compartment panel in the case of console units Information found on the nameplate includes the following Model number Serial number Type of refrigerant used and amount of charge in console units Amperage free load amperage LRA locked rotor amperage indicates the amperage the unit draws at the instant of starting f Electrical rating of the unit maximum and minimum voltage and hertz requirement g Phase pou mM BMictur Sise white sirsa White calor s Commom Di pet ion Capaciknr Rating Ampurmes dran while the matur runm TrigcAt
136. wiring for a Permanent spalt amp apacitar nin hermete sor compressors Typical Wiring f r Lapacitere Start Start Capacitar Compressor Matrr AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 63 HARD START KIT A hard start kit is a combination relay start capacitor and overload protector Primarily this kit see fig 47a was designed to start older compressors that due to their age and normal wear become hard to start Very often a compressor that is thought to be defective can be restored to service by using a hard start kit A hard start kit is a great tool for the service technician It eliminates a lot of work and time spent in testing several components and looking for the defective part when a compressor fails to run or cycles on overload It is inexpensive and can be used on almost all 115 VAC compressors under 1 2 hp Some hard start kits are designed for use on compressors operating on 208 230 VAC and on air conditioners up to several tons The wires on the kit are either color coded or individually labeled Start Run and Common Figure 45a HOW TO USE A HARD START KIT Disconnect the power from the unit Remove the overload protector and starter relay Connect the start terminal of the compressor to the wire on the kit marked Start Connect the run terminal of the compressor to the wire on the kit marked Run Connect the common terminal of the compressor to the wire on the kit marked Comm
137. 0 185 8 70 6 6 34 1 157 8 70 7 270 207 9 80 1 1 43 5 186 0 86 4 280 231 8 90 2 6 54 1 217 5 104 2 290 257 5 100 6 3 66 2 252 7 124 3 300 285 0 Vapor pressures are shown as psig Indicates inches of mercury vacuum TEV CAPACITY INCREASE FOR SUVA REPLACEMENTS TO R502 Suva Equipment used Refrigerant in buildings HP62 1196 HP80 14 81 22 TEV CAPACITY INCREASE FOR SUVA REPLACEMENTS TO 412 Suva Equipment used Equipment used Refrigerant in buildings in vehicles MP39 3596 N A MP52 2896 2796 MP66 3896 N A HFC 134a 3896 3096 NOTE MP39 and MP66 are recommended for use only in buildings AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 415 SATURATED VAPOR TEMPERATURES OF R12 AND ITS SUVA REPLACEMENTS Temperature F Temperature C psiA kPA psiG R 12 134a MP39 MP52 MP66 Bar R 12 134a MP39 MP52 MP66 122 5 29 3 22 1 23 2 14 8 26 6 80 0 80 35 2 31 1 31 7 27 1 33 6 14 7 0 21 6 14 9 16 0 7 4 19 4 100 1 00 30 1 26 3 26 9 22 2 28 9 16 7 2 16 1 9 8 10 8 2 1 14 3 110 1 10 27 8 24 2 24 8 20 0 26 8 18 7 4 11 1 5 2 6 1 2 6 9 7 120 1 20 25 7 22 3 22 8 18 0 24 8 20 7 6 6 5 0 9 1 8 7 0 5 4 130 1 30 23 8 20 5 21 0 16 1 23 0 22 7 8 2 9 3 0 22 11 1 1 5 140 1 40 21 9 18 8 19 2 14 3 21 3 24 7 10 1 6 6 7 5 9 14 9 2 2 150 1 50 20 1 17 1 17 6 12 7 19 6 26 7 12 5 4 10 1 94 18 5 5 7 160 1 60 18 5 15 6 16 0 11 1 18 1 27 7 14 9 0
138. 1 Li Bese Swibch Interior Light uf Defrost Bimnkal Defrost Heater r T4 CAS 152 Chee Drain Haabter load Protector Thermastat 74 L s i 1 Evaporator fan Motor 52 ohms P 7 2ODn snmEsE yan Babort 176 Obes hA mt 1 ect gt mollia Heater i Heater 4 Def rest 1 I 1 Figure 184a A SCHEMATIC WIRING DIAGRAM OF A TYPICAL FROST FREE AUTOMATIC DEFROST REFRIGERATOR As the timer motor turns it moves a cam within itself The cam changes the direction of current flow through its contacts This contact position change takes the unit into the defrost or cooling cycle Cooling cycles last six eight or twelve hours and defrosting periods do not last longer than twenty one minutes depending upon the timer used 312 hw amp DHz Lins De Enargi eed Eine Dear Sei keh 24 Ohma Difronk Bimskal Def rcat Hoa bee DNES Drain 9 Ey aparator 62 ohms P bs Cuandensmsz _ Fan Det ront Timer H j Figure 184b A SCHEMATIC WIRING DIAGRAM OF A TYPICAL FROST FREE AUTOMATIC DEFROST REFRIGERATOR IN THE DEFROST CYCLE The timer shifts to number 2 position and takes the unit into the defrost cycle The duration of this cycle is no longer than twenty one minutes Pay close attention to the direction of the flow of electricity It starts from L1 the hot
139. 13 4 12 7 21 8 8 9 170 1 70 16 9 14 1 14 5 9 5 16 6 30 7 16 12 3 165 15 8 25 0 12 0 180 1 80 15 4 12 7 13 1 8 1 15 2 32 7 18 15 5 194 18 8 28 1 14 9 190 1 90 13 9 11 4 11 8 6 7 13 8 34 7 20 185 22 2 216 310 17 8 200 2 00 12 5 10 1 10 5 5 4 12 6 36 7 22 214 24 9 24 3 33 7 20 4 210 2 10 11 2 8 8 92 A41 113 38 7 24 242 274 26 9 364 23 0 220 2 20 9 9 7 6 8 0 2 8 10 1 40 7 26 269 299 29 4 38 9 25 5 230 2 30 8 6 6 5 6 8 L6 90 42 7 28 29 5 32 2 318 41 4 27 9 240 2 40 7 4 5 4 5 7 05 7 8 44 7 30 32 0 345 341 43 8 30 2 250 2 50 6 2 4 3 4 6 0 6 6 8 46 7 32 34 4 367 364 460 32 4 260 2 60 5 1 3 2 3 5 17 57 48 7 34 367 38 9 38 5 482 34 5 270 2 70 4 0 2 2 2 5 28 47 50 7 36 39 0 41 0 40 6 50 4 36 6 280 2 80 2 9 12 31 5 3 8 3 7 52 7 38 41 2 43 0 42 7 52 5 38 6 290 2 90 1 9 0 3 0 5 48 27 54 7 40 43 3 449 44 6 54 5 40 6 300 3 00 0 8 0 7 0 4 5 8 1 8 56 7 42 45 4 468 46 6 565 42 5 310 3 10 0 2 1 6 1 3 6 7 0 9 58 7 44 474 487 484 58 4 44 4 320 3 20 1 1 2 5 2 2 7 6 0 1 60 7 46 49 4 50 5 50 3 00 3 46 2 330 3 30 2 1 3 3 3 1 8 5 0 9 62 7 48 51 3 52 2 52 0 62 1 47 9 340 3 40 3 0 4 2 4 0 9 4 1 8 64 7 50 53 2 53 9 53 8 63 9 49 7 350 3 50 3 9 5 0 4 8 10 3 2 6 66 7 52 55 0 55 6 55 5 65 6 51 3 375 3 75 6 1 7 0 6 9 12 3 4 6 68 7 54 56 8 57 2 57 1 67 3 53 0 400 4 00 8 2 8 9 8 8 14 3 6 5 70 7 56 58 5 58 9 58 8 69 0 54 6 425 4 25 10 2 10 7 106 16 2 8 3 72 7 58 603 60
140. 14 1 17 0 145 15 3 68 7 54 21 2 15 4 20 0 18 7 375 3 75 12 9 15 9 13 4 14 1 70 7 56 22 8 16 9 21 6 20 3 400 4 00 11 0 14 1 11 6 12 3 72 7 58 24 4 18 4 23 0 21 8 425 4 25 9 2 12 4 9 8 10 6 74 7 60 25 9 198 245 23 3 450 4 50 7 5 10 7 8 2 8 9 76 7 62 27 4 213 26 0 24 7 475 4 75 5 9 9 2 6 6 7 3 78 7 64 28 9 227 274 26 1 500 5 00 4 3 7 6 5 0 5 7 80 7 66 30 3 24 0 28 8 27 5 525 5 25 2 8 6 2 3 6 4 3 82 7 68 31 7 25 4 30 1 28 9 550 5 50 1 3 4 8 2 2 2 8 84 7 70 33 1 26 7 315 30 2 575 5 75 0 1 3 4 0 8 1 5 86 7 72 34 4 28 0 32 8 31 6 600 6 00 1 5 2 1 0 6 0 1 88 7 74 35 8 2933 34 1 32 8 625 6 25 2 8 0 8 1 8 1 2 90 7 76 37 1 30 6 35 4 34 1 650 6 50 4 1 0 4 3d 2 4 92 7 78 38 4 31 8 36 8 35 4 675 6 75 5 4 1 6 4 3 3 6 94 7 80 39 7 33 0 378 36 6 700 7 00 6 6 2 8 5 5 4 8 99 7 85 42 8 36 0 40 8 39 6 725 7 25 7 8 3 9 6 7 6 0 104 7 90 45 8 38 8 43 7 42 5 750 7 50 9 0 5 1 7 8 7 1 109 7 95 48 6 41 6 46 5 45 2 775 7 75 10 1 6 1 8 9 8 2 114 7 100 51 4 44 3 49 2 47 9 800 8 00 11 2 7 2 9 9 9 2 119 7 105 54 1 46 8 51 8 50 5 825 8 25 12 3 8 2 11 0 10 3 124 7 110 56 8 49 3 54 3 53 0 850 8 50 13 3 9 2 12 0 11 3 129 7 115 59 3 51 8 56 8 55 5 900 9 00 15 4 11 2 14 0 13 3 134 7 120 61 8 54 1 592 57 9 950 9 50 17 4 13 1 15 9 15 2 139 7 125 64 2 56 4 61 5 60 2 1000 10 0 19 3 14 9 17 7 16 7 144 7 130 66 5 58 6 637 62 4 1050 10 5 21 1 16 6 19 5 18 7 AIR CONDITIONING AND REFRIGERATION RE
141. 162 Courtesy of White Rodgers Division of Emerson Electric Company personnel and equipment Figure 66a Make it a habit to make a pencil sketch or tag the wires with a piece of tape before removing a capacitor By doing this there will be no doubt about the proper connections when installing a new capacitor AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 91 TESTING CAPACITORS The best way to test a capacitor is to replace it with anew one of the same rating e TESTING CAPACITORS USING AN OHMMETER Disconnect the power to the unit Use insulated screwdriver to shunt between the capacitor terminals to discharge it Then remove the capacitor from the circuit Set the ohmmeter on its highest scale Touch the two capacitor terminals with the two leads from the meter If the capacitor is in good condition the meter should register zero ohms and then move slowly back toward infinity Switch the leads and repeat step d to get the same results Otherwise replace the capacitor The needle should deflect to infinity and stay there from the very beginning if the capacitor is open The needle should register O and stay there if the capacitor is shorted rd o TESTING CAPACITORS USING A DIGITAL CAPACITOR TESTER They are inexpensive and very accurate Disconnect power from the unit Discharge the capacitor as in Ib above Turn on the digital tester and connect its leads to the capacitor t
142. 370 by replacing them with ones with higher rpm or provide for proper air distribution air circulation over the entire evaporator coil without any restriction in the airflow 1 4 Excessive Accumulation of Oil in Evaporator and Low Superheat Too much oil in the evaporator slows the liquid refrigerant evaporation rate because oil acts as an insulator See sec Il 1 You could alter the suction piping to increase liquid refrigerant velocity to provide proper oil return or install an oil separator if required It may also be possible to remove the excess amount of oil from the crankcase 11 5 Poor Bulb and Equalizer Location and Low Superheat The bulb should be clamped to the suction line near the evaporator outlet on a horizontal line See figs 110e and 203 Clean a place on a free draining suction line before clamping the bulb in place Insulate the remote bulb from the ambient air Locate the equalizer line as close to the bulb as possible on the end away from the evaporator on the downstream side as shown in figure 201 If the equalizer line is installed upstream of the bulb and the packing leaks the refrigerant passing through the equalizer line will keep the sensing bulb artificially cold thus forcing the TEV to remain closed i e high superheat If the above occurs with the equalizer line piped downstream refrigeration will still continue A small leak has very little effect on superheat However a large leak
143. 5 8 OD are available i 1 lmpcorrwect Correct Courtesy of ALCO Controls AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 389 WATER COOLED CONDENSERS Circulating water removes heat from water cooled condensers When the flow of this cooling water becomes too slow or if it stops the pressure in the condenser rises very rapidly causing the high pressure control to shut off the unit Once the compressor stops running the head pressure drops sharply and very soon it reaches the high pressure control cut in point causing the power to the compressor to be restored The unit resumes operation and the short cycling continues The interruption or reduction of this circulating flow of water can be due to a defective or out of adjustment valve a clogged up screen a decomposed rubber condenser hose through which the exhaust water runs or a water line in the condenser choked with sediment REASONS FOR A RESTRICTED WATER FLOW Leaky valve bellows Valve replacement is required Leaky valve Valve replacement is required Valve adjusted for too slow a flow Readjustment of valve is required Partial or no flow of water due to obstructed screen Cleaning is required Chattering valve Valve replacement is required Valve obstructed by an excessive amount of sediment Valve cleaning or replacement required EXCESSIVE WATER FLOW Excessive water flow results in the use of more water than actually needed
144. 6 0 134 0 202 0 269 0 458 UNIT Btu 9 000 12 000 18 000 24 000 36 000 48 000 60 000 84 000 120 000 240 000 360 000 480 000 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 287 LIQUID LINE TUBING SIZE IN INCHES OD i4 3 8 0 250 0 021 0 420 0 036 0 75 0 127 0 260 0 450 1 2 5 8 3 4 7 8 0 009 0 015 0 028 0 095 0 200 0 340 1 1 8 0 009 0 029 0 058 0 100 To determine the total pressure drop in the liquid line multiply the corresponding figure by the length of the liquid line Figure 178f lt LIQUID LINE PRESSURE DROP USING REFRIGERANT R 12 BASIC ELECTRICITY This section provides simplified instruction in basic electricity and illustrates typical circuits and symbols You will learn step by step how to read refrigeration and air conditioning schematic wiring diagrams through typical examples of the normal operation of these units It teaches how to use diagnostic tools such as ohmmeters ammeters and voltmeters to troubleshoot electrical malfunctions that commonly occur in refrigeration and air conditioning units ja SLO 289 290 BASIC ELECTRICITY The electricity for mass consumption is created by large generators and conducted to final destinations with the help of transformers to maintain its force and energy The large electric generators in a city s power and light company move current through heavy cables to transformer
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146. 95 2 The air coil type see fig 69 This type of thermostat is installed somewhere within the refrigerated area preferably not near a door that is opened frequently or in the path of the air currents in the unit to prevent false reactions The refrigerant in the coil expands and contracts with temperature changes and transmits signals to the thermostat to control the operation of the unit When an air coil thermostat is purchased determine its cut in and cut out range from the instructions or the dealer to see if it is suitable for the particular application intended As it will be shown later there is a relation between saturated refrigerant vapor pressure in the sealed system and the temperature produced The operation of the temperature regulating pressure controls is based on this principle Most commercial units use this type of temperature control Some units employ both thermostat s and pressure control s Manually operated thermostats are still widely used in commercial kitchen refrigeration where those owners prefer to adjust temperatures periodically to meet their needs Pressure controls require adjustment by qualified technicians and cannot be manually adjusted by the customer EPH EFA contrallad Campraaaar Air coil type thermostat installed inside Meu nivem Ope ran 1 the area where temperature is to be controlled Low pressure control and a manually adjusted thermosta
147. 96 to 396 of original R 502 charge If system is equipped with a small hermetic compressor which has no oil drain a R 502 must be removed from the system 10 20 inHg vacuum needed to remove charge b Drain the existing oil out the compressor suction line c Reinstall compressor d Evacuate system to 29 9 inHg vacuum e Leak check system f Charge system with SUVA HP 62 SUVA 123 HCFC 123 REFRIGERANT SUVA 123 HCFC 123 a nonflammable liquid refrigerant is the environmentally acceptable replacement for R 11 With a boiling point of 81 7 F 28 C it is used in centrifugal chillers and the brine system It 412 is sold under different trade names such as SUVA Centri LP SUVA 123 HCFC 123 or Hydrochlorofluorocarbon 123 It must never be used as an uncontained flushing agent in refrigeration repairs Drums used for this refrigerant are color coded light gray and must be stored in an upright position and placed out of direct sunlight at temperatures below 125 F 52 C If HCFC 123 drums are to be transported or refilled indoors an air monitor will be required When charging or vacuuming a chiller HCFC 123 drums must be connected to the chiller with both a vent line and a liquid transfer line This is done to minimize venting the gas into the work area while liquid HCFC 123 is being transferred and also to avoid an overpressure or vacuum condition in the drum If HCFC 123 vapor comes into contact with high temp
148. AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY A Complete Step by step Repair Guide for Commercial and Residential Air Conditioning and Refrigeration Units 2009 EDITION REPAIRS AND INSTALLATION OF AIR CONDITIONERS AND HEAT PUMPS WALK IN COOLERS FREEZERS REFRIGERATORS WATER COOLERS SALAD BARS OPEN AND CLOSED REFRIGERATED CASES ICE MACHINES STEP BY STEP RETROFIT INSTRUCTIONS FOR SUVA REFRIGERANT Copyright 2010 by Gohari Library of Congress Control Number 2009904992 ISBN Hardcover 978 1 4415 3945 8 Softcover 978 1 4415 3944 1 All rights reserved No part of this book may be reproduced or transmitted in any form or by any means electronic or mechanical including photocopying recording or by any information storage and retrieval system without permission in writing from the copyright owner SINCE CONDITIONS OF USE OF THE INFORMATION IN THIS BOOK ARE OUTSIDE OF OUR CONTROL NEITHER AIR ZONE NOR THE AUTHOR ASSUME ANY RESPONSIBILITY IN CONNECTION WITH ITS USE PUBLISHED BY AIR ZONE 503 GRABO DR SAN ANTONIO TEXAS 78216 To order additional copies of this book contact Xlibris Corporation 1 888 795 4274 www Xlibris com Orders QXlibris com 57321 CONTENTS Acknowledgment cicicescccsscesiessscaessecvevedgedesseusnessevsveysudeusisecsessdensessdens vii MRE 1 Rules for Personal
149. Auedujo Suunioejnue g 0283 se1uno AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 205 WATER FOUNTAIN TROUBLESHOOTING CHART Problem and Possible Cause Remedy Water Does Not Come Out Cold while Compressor Is Running Freon leak in system Linted condenser Restriction Bad condenser fan Bad pressure control Faulty expansion valve Extensive use without giving water a chance to cool Leak in push button valve Inefficient compressor Repair leak change filter drier evacuate and recharge Clean condenser Check by using touch method Change filter drier evacuate and recharge Repair or replace as required Check and replace if necessary Check and replace TEV valve Capacity of unit may be too small for number of people using it Repair or replace valve Replace compressor Water Does Not Come Out Cool and Compressor Does Not Run 1 No power to the unit 2 Faulty motor control pressure Incorrect voltage Bad thermostat In units that use a cold control in lieu of a pressure control Bad starting relay Faulty starting capacitor Faulty overload protector Bad connection or broken wire Shorted compressor Check for blown fuse or tripped circuit breaker Observe safety instructions and bypass the two terminals in the control If the compressor starts it could be a bad pressure control or a leak If manifold gauge shows vacuum in the black pressure or close there
150. Bnatar Unit In Defrost Cycle In figure 186c and d hot gas is circulated from the compressor to the receiver flowing to the evaporator through the suction line A timer takes the system to the defrost cycle at a predetermined time 1 Defrosting solenoid valve is energized to open the line from the receiver to the suction line 2 three way solenoid valve becomes energized closes the line to the compressor and allows hot vapor refrigerant to circulate through the suction line The function of the hold back valve is to reduce the pressure of the hot vapor refrigerant as it is drawn into the compressor 3 Hot refrigerant passes to the cold evaporator heats the evaporator and changes to liquid refrigerant due to its lowered temperature 4 Theliquid refrigerant bypass The purpose of a check valve in the condenser outlet is to prevent refrigerant from backing up from the receiver into the condenser Figure 186d Ling De Energited 1 G0 Line Energized the TEV through a check valve and through the liquid line flows to the receiver There is an electric heating element in the receiver which is activated in this cycle to vaporize the returning refrigerant in the receiver for more defrosting The purpose of the pressure regulating valve is to sustain favorable hot refrigerant pressures and temperatures Defrosting of the evaporator in this system normally takes six to ten minutes The sensing bulb of a
151. CCESS WALWES In residential units piercing valves must be installed on the discharge and suction lines prior to charging the unit with oil In commercial units the service valves on the compressor discharge side or on the receiver and on the suction side may be opened and closed with a service wrench More about service valves on page 155 Courtesy of Henry Valve Co ACCESS VALVES Valves in figure 45k can be installed on the compressors having high and low side access tubes or on the tubing Remove the valve cap and stem from the valve clean the joints with acetone as well as sandpaper braze the correct size valve on the tube and allow it to cool before replacing the valve stem and cap Numbers 1 2 and 3 are access valves that are silver brazed to copper tubing Number 1 can be used on various diameters of tubing Number 4 shows the removal of the valve core from the body Numbers 5 6 and 7 are T fittings installed on high or low side refrigerant lines Numbers 5 and 7 are silver brazed and number 6 is connected by flared connections Number 8 shown with its cap has an extended tube It can be installed on the compressor access tube as numbers 1 2 and 3 or on larger sized tubing where in line fittings may not be available Drill a hole in the wall of the tubing insert the valve tube in the hole and silver braze the joint Take great care to prevent foreign particles from entering the system INDICATIONS OF A
152. Change valve Change valve to match system refrigerant and desired pressure Install in proper flow direction Adjust condenser bypass regulator setting to the appropriate level Normally set 20 psi below the condenser pressure regulator IPR setting 376 FLOODED HEAD PRESSURE CONTROL FOR AIR COOLED CONDENSER SYSTEMS Figure 204 Bequleber Vallee Discharge pressure Scaled Cond ee above valve setting flow through condenser azi SINGLE VALVE Lal memon A OPR Downstream inlet pressure regulating valve IPR Upstream inlet pressure regulating valve Figure 206 VALVE AND CHECK METHOD TWO VALVE METHOD Bound Presume T asinum aiv Wed rez Ate Goobed pega later fo lencid 1 2 Low Discharge Pressure Probable Cause Remedy Ambient air too cold Install head pressure control system b Water supply to condenser too cold Check repair and adjust condenser water cooling facilities Water quantity not being regulated properly Install or repair water regulating valve through the condenser Refrigerant level low Winter charge lacking Add necessary refrigerant per proper charging method Condenser fan and water switches improperly Reset condenser controls set Fan cycling variable speed not operating Check motor and pressure setting Uninsulated receiver in cold ambient acting Insulate and or heat receiver as condenser
153. Compound gauge to the valve on the suction line and high pressure gauge to the liquid line By opening the valves on the manifold freon can be released through the middle hose on the manifold By law the middle hose must be connected to a recovery machine p 139 to recover the freon into an empty cylinder to be used again Details about this can be obtained from any refrigeration supply house where these tools are sold 3 As shown in fig 84 connect a vacuum pump to the unit and pull a vacuum to 29 of mercury close the valves on the manifold and turn off the vacuum pump 4 As shown in fig 45i submerge the manifold middle hose in the compressor oil 5 Open the manifold low pressure valve and allow oil to be drawn into the compressor CAUTION Shut off the low side manifold valve while the end of the hos is still submerged in oil to prevent air from entering the system ADDING OIL TO COMPRESSOR With the unit turned off pull 29 of vacuum as shown in Fig 84 submerge the hose from the middle of the manfold into the oil open the compound guage valve on the manifold to let oil flow into compressor Close valve with the end of hose still submerged to prevent penetration of air into the system Oil is added to the compressor while the unit runs Figure 45i Access valves come in a variety of sizes and styles AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 69 Figure 45j 6 S ai Cm TERWICE WHERE A
154. D PRESSURE CONTROL SYSTEM Figure 199a FOR UNITS OVER FIFTEEN TON CAPACITY AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 365 Another cause of restriction is the formation of wax in the sealed system restricting the flow of refrigerant This may be indicated by a sudden rise in suction pressure when the system warms up after a shutdown To check while the system is running use a heat gun to warm the TEV to melt the ice and note the rise in the suction pressure The heat gun usually does not melt the wax making wax difficult to discover Wax in the system may indicate that the wrong type of oil is being used Waxing can occur in low temperature units such as those with evaporator temperatures of 25 F Wax usually liquefies and flows again near or higher RECOMMENDED SIZES FOR REFRIGERANT LINES Btu h LENGTH OF RUN 15ft 25ft 36ft 50ft 100ft OD OD OD OD OD Inches Inches Inches Inches Inches ACCEPTABLE LIQUID RECEIVER VOLUMES Refrigerant Weight Ib Suction Line HP Volume R12 R22 R 500 R 18 500 22 000 5 8 5 8 5 8 in 502 22 000 24 000 3 8 5 8 5 8 3 4 24000 34000 5 8 5 8 3 4 3 4 3 4 38 000 40 000 3 4 3 4 7 8 7 8 7 8 1 2 150 68 62 59 6 3 40 000 44 000 3 4 7 8 7 8 7 8 7 8 3 4 225 103 9 3 89 94 44 000 51 000 7 8 7 8 7 8 7 8 7 8 1 300 13 7 124 11 9 12 9 53 000 66 000 7 8 7 8 7 8 118 11 8 1 450 20 5 186 179 193 Liquid Line 600 274 248 238 258 18 500 22 000 5 16 5 16 5
155. E OR ELECTRONIC 0 080 A AND 1 2 A IGNITION MODULE Courtesy of Honeywell AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY A POWER SUPPLY PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED FOR SYSTEMS WHERE THERMOSTAT MUST CONTROL FAN DIRECTLY IN HEATING SET FAN OPERATION SWITCH TO ELEC POSITION USE ONLY ONE TRANSFORMER AND JUMPER R AND RC A FOR SINGLE TRANSFORMER SYSTEM JUMPER R AND RC Jit 1 A typical thermostat controlled circuit in a two transformer system Gas heating and electric cooling A typical thermostat controlled heating cooling circuit in a two transformer system one for heating one for cooling A typical relay connection operating a two speed blower fan in the furnace 353 E t POWER SUPPLY PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED PRIMARY CONTROL SUCH AS GAS VALVE OR ELECTRONIC IGNITION MODULE CURRENT DRAW FOR W OR Y MUST BE 0 08 A OR GREATER W Y PLUS G MUST BE 1 2 A OR LESS ON T8600D HEATING SYSTEM POWER MUST BE ON YEAR ROUND Two Speed Motor To M vnlt coetrol circuit Blue f S 1 Ler Balay Errn M Furnace la ar oher mettrking deviled Twn 3pesd Boor Linme Val tage Courtesy of White Rodgers Division Rare Wodl e of Emerson Electric Company 354 COMPRESSOR TROUBLESHOOTING CHART Commercial Units Problem and Possible Cause 1 Unit Won t S
156. E REFRIGERATOR Color coding is usually indicated by BK black W white OR orange Y yellow and R red In a more sophisticated unit an energy saver switch deactivates the mullion and case heaters by cutting off power to them In this unit they are always on as long as the power is on Pay close attention to the direction and path of current energizing or de energizing the different components that take the unit into the cooling or defrost cycle See pp 315 and 314 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 315 Line De Engrgirad Lina 1219 db Dele hear Bitch Dswrinad Protector am TT tow 2295 Grain Heater Ew 1640 phas 1 Matar G0 fhe Ohms Came Heater iT Tii POC Chew gt Figure 185b H SCHEMATIC WIRING DIAGRAM OF A CYCLE DEFROST REFRIGERATOR IN THE COOLING CYCLE As long as the thermostat is not satisfied closed the unit stays in the cooling cycle Note the direction of the current flow It starts from L1 the hot terminal in the wall receptacle flows through the starting relay the compressor and the overload protector at point J Since the resistance of the evaporator and the drain heater is high and because current always follows the path of least resistance the current flows through the thermostat path with practically no resistance
157. EASY 239 airflow is perpendicular at a right angle to the motor shaft See fig 140a They are widely used in central air conditioning systems where the air is required air to be directed vertically see fig 147 Figure 147 CAGE BLOWER FAN Sometimes this type of blower fan is driven by a belt and pulley connected to a separate motor see fig 148 Most central air conditioners swamp coolers commercial kitchen ventilators etc use this type of fan 8 typed owl akrar air force fee carter amd Bis Chee dr eucrdumarr i eines for ui pe pa be bini adus eue biri abies Furor pales gru porary ed and do rat Figure 148 PC EENTRAL CAT rey riim beigi Tamam m been Tani gars 240 2 COOLING AND HEATING BY AIR CONDITIONERS In commercial and residential refrigeration controls can be adjusted to have the evaporator produce and sustain subzero temperatures But in air conditioning units evaporator temperatures do not go that low Since the most comfortable room temperatures range between 74 F and 80 F at 50 humidity the evaporator temperature is normally set between 40 F and 50 F And since that temperature is well above the freezing point defrosting of their cooling coil is not necessary As air is moved through the coil it becomes cooler or warmer for h
158. Geren Te eld co aad rhe niundonr adber air Hs faai abso ed The tion odd ohare by Har lies odi ae Leer ursi b iniu beating merda Hust Pump Heating E 8 s a a i 5 Vagn e Lingala amp liquid Vapor Hefrigeramt 268 Figure 175 kit Reis a Diasa am Fig Bap rs Crmrhrass eater l _ P Contactar at o Wuticor JU Tharscakak 1 Lamia E Lii Al oial wiring Tiaris valva diq irrin CONTROL PANEL Atypical control panel for a central A C split system heat pump The solid state heat pump defrost board The following are the three usual methods of wiring the defrost board into the system The connections to the 24 volt system through a defrost relay Connecting the defrost board into the system through a defrost relay and a disc sensor Connecting the defrost board into the system through a defrost relay and a wall thermostat Identifies terminals on B Auedwog 21329 3 uosJau3 jo UOISIAIG 1 8 Jo AsayinoD AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 269 THE DEFROSTING OF THE HEAT PUMPS Heat pumps are used in the cold season and the outside coil of these units acts as an evaporator when the unit is in the heating mode Due to the low ambient and coil temperatures ice tends to build up on the
159. Gun the shell and connect the power G LU I supply The use of a dolly when moving and installing these units i a is a big help Never attempt to lift the unit by the tubing and never Courtesy of MALCO Products Inc force the unit into the casing AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 235 A polarized circuit one with a ground wire must be used for air conditioners Apartments use mostly wall mounted units The thermostat setting on most units is adjustable between 55 F and 60 F 12 C and 16 C The thermostat bulb a tubing is fastened to the evaporator Avoid bending the bulb as it may kink or crack and impede its function The thermostat bulb is covered with a plastic guard The function of the guard is to protect the bulb from extremes in temperature and to prevent short cycling by frequent turning on and off of the unit The capacitor s and relays for heat pumps for these units are installed behind the control knobs on the front panel see fig 142 This plastic front panel is usually held on by a few small screws or clips Behind the plastic panel covering the entire front of the evaporator a dust filter is held in place Because wall and window units use permanent split capacitor run motors they do not require a starting relay see fig 45 They also use capillary tubes Location of capacitors and relay behind the control panel of the window unit Run capacitor for fan and compresso
160. ING AND REFRIGERATION REPAIR MADE EASY 35 How are the pressures in a sealed system checked p 27 What is the primary purpose of a filter drier pp 27 28 What are other names for a defrost bimetal p 28 What is the primary purpose of a termination switch p 28 What is the defrost bimetal clipped to p 28 How many types of condensers are used in residential refrigeration p 29 How many types of evaporators are there figs 14 15 Where is an accumulator installed p 31 What is the primary function of a capillary tube p 31 What is the most important thing to consider before replacing a capillary tube p 31 How many types of defrost systems are there figs 16 18 17 19 pp 30 31 32 What are the most common types of condensers used in residential refrigerators and freezers pp 29 30 What is the purpose of insulating materials in refrigerator walls fig 6 p 17 How is airflow regulated in a side by side refrigerator p 20 fig 9 What is the principal difference between a refrigerator and a freezer p 22 What components are activated in opening the flow of hot gas in a hot gas defrost system fig 16 16a p 19 Why shouldn t ice build up on the evaporator coil p 32 Why is fan forced circulation used in frost free refrigeration p 30 What is the capillary tube connected to p 31 What is the function of an accumulator p 31 THE BRAZING AND FLARING METHODS OF CONNECTING TUBING
161. ION REPAIR MADE EASY 49 A rotary compressor also operates on a principle similar to the automotive rotary engine It can be hermetically sealed or rely on an external conventional electric motor They are used in commercial and residential units As the rotor revolves inside the cylinder on an eccentric cam the spring loaded vanes pass the intake and discharge ports As one vane passes the intake port suction begins and cold vapor is drawn into the cylinder As the rotor continues its turn the gas is compressed When the other vane clears the discharge port the gas is propelled through the high pressure line into the condenser See fig 29 THE PRINCIPLE OF THE ROTARY Figure 29 COMPRESSOR As the rotor turns cold vapor is drawn in from the evaporator and compressed causing its temperature to rise high pressure high temperature It is then forced into the condenser Rotary compressors are very susceptible to liquid refrigerant As a safety measure they are equipped with an fi accumulator on the suction inlet to prevent any unvaporized refrigerant from getting into the compressor motor pm Lice pes corre m i r F In a rotary hermetic compressor the circular motion of the motor rotor in the top causes the rotary compressor in the bottom to turn A motor rotor B motor stator C rotary compressor D compressor terminals E accumulator F motor winding G compressor discharge conn
162. Ini TEE Hefrlgerabcr Lamp Lamp Switch 37 Water Inlet l os Solenoid Talve ei sy FEES J Tee Maler a i Optional i 1 _ Frost Free Refrigerator Figure 183a See pages 18 19 Figures 183a b and c show a typical schematic of a frost free refrigerator Most refrigerators of this type have a similar illustration AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 309 LN I 5 m LIA Dverioad Protector Ewaporeter Fan Motor i nhas i assasin ao Fearenptal contro saeco urmcuta by J car EN is fg UM Monbar 1773 Ohma Faorgy Saver Seitch Beater pl Ws Mack felrigerator Lam Es Lamp Brice 7 Bos Eg e a 1 Water alat Ma Solenoid Valvm i nn ca J fee maker Hook Up LLL iin Optional i L Lins D amp Enargired Lil Ling Energized Figure 183b A SCHEMATIC WIRING DIAGRAM OF A FROST FREE REFRIGERATOR IN THE DEFROST CYCLE The timer shifts to number 2 position and takes the unit into the defrost cycle This cycle will last no longer than twenty one minutes Pay close attention to the direction of the flow of current It starts from L1 the hot terminal in the wall receptacle flows through the timer terminal number 2 the defrost heater the def
163. LID STATE FAN Liquid temperature at the TEV inlet RA aL 6 EME l 10 Internally Equalized TEV and High Superheat An internally equalized TEV must not be used on evaporators through which too much pressure drop occurs Check the rule of thumb for selecting an externally equalized TEV Use an externally equalized TEV and make sure that the external equalizer line is connected properly See section II 5 concerning poor location for bulb and equalizer in this section Generally internally equalized valves are neither used in systems using a refrigerant distributor nor in units above a two ton capacity l 11 Gas Charged TEV and High Superheat If the gas charged TEV loses control the valve head and tubing must be kept warmer than the remote valve Heat tape can be used to wrap the valve sensing bulb and tubing The valve body can be insulated or installed outside the refrigerated space 1 12 Sensing Bulb Failure or Loss of Charge and High Superheat If this occurs due to a puncture or a sharp bend replace the sensing bulb assembly or replace the TEV 1 13 Wrong Thermostatic Charge and High Superheat The TEV sensing element is charged with liquid refrigerant Some sensing elements are charged with the same type of refrigerant being used in the unit AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 367 and some use a different type or a mixture of different fluids to provide the desi
164. Load Locked Rotor FullLoad Locked Rotor Use a 1 10 3 0 18 0 1 5 9 0 clamp on 5 1 8 3 8 22 8 1 9 11 4 ammeter to 2 1 8 44 264 2 2 13 2 determine 5 8 34 8 2 9 17 4 E 1 3 72 43 2 3 6 21 6 E 9 8 58 8 4 9 29 4 while the E 2 13 8 82 8 6 9 41 4 motor 2g 1 16 0 96 0 8 0 48 0 Compressor 58 1 20 0 120 0 10 0 60 0 operates E 2 24 0 144 0 12 0 72 0 8 2 3 34 0 204 0 17 0 102 0 Voltage Voltage Voltage AC Single Phase AC Single Phase AC Single Phase Conversion 120 208 240 277 120 208 240 277 120 208 240 277 Table Watts Amperes Watts Amperes Watts Amperes for 500 4 2 2 4 2 1 1 8 2500 20 9 12 0 10 4 9 0 4500 37 5 21 6 18 8 16 3 Watts Amperes Volts 1000 8 3 4 8 4 2 3 6 3000 25 0 14 4 12 5 10 8 5000 41 7 24 0 20 8 18 0 1500 12 5 7 2 6 3 5 4 3500 29 2 16 8 14 6 12 6 2000 16 7 9 6 8 3 7 2 4000 33 3 19 2 16 7 14 4 CHECKING OUT THE SOLID STATE TEV THERMAL ELECTRIC VALVE As a general rule of thumb when a thermal electric valve TEV is incorporated in a refrigeration system that system becomes more energy efficient Sooner or later every service technician will be faced with troubleshooting and servicing an electric valve system This section will help you to successfully meet that challenge Discharge Actually the job is easy even though it is entirely different from working with
165. OID VALVES Asolenoid valve is an electromechanical device which operates by creating and eliminating a magnetic field It is primarily composed of a coil of wire windings and an armature metal rod or plunger When the circuit is closed the coil creates a magnetic field which causes the metal rod to move upward its valve seat The seat when free of its obstruction allows refrigerant to flow through it When the electrical circuit is opened the magnetic field disperses and the plunger falls back into its seat This type of valve is known as a direct acting solenoid valve Fair 5n DIRECT Fac THO x Tn Peover uppliy A SOLEHCED VALVE cated ET LI UE i E of luis iu iius EE Body Assembly ORANA FE NaxLllarR 7 Cundanser Rnogmal Condaumger Pupa 4 An feet a reira eh be zpnrermeri asarim n pakel a dueesqxri oko vahy be Hus hanai caciarr ng Hoir es placer of s suem Thes neige decode fuvcagi anila cedera when us CETEpETHT4 R axrerch s pacis pini Cinergy vl AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 149 Pilot operated solenoid valves use a combination of the solenoid coil and the line pressure to operate In this type of valve the plunger is attached to a needle valve covering a pilot orifice rather than the main port The line pressure holds an independen
166. PAIR MADE EASY 417 147 9 135 68 8 60 8 65 9 64 6 1100 11 0 22 9 18 3 21 2 20 4 154 7 140 71 0 62 9 68 1 66 8 1150 11 5 24 6 19 9 22 8 22 1 159 7 145 73 2 650 70 2 68 8 1200 12 0 26 2 21 5 24 4 23 6 164 7 150 75 4 670 722 70 9 1250 12 5 27 9 23 0 25 9 25 2 169 7 155 77 5 690 74 2 72 9 1300 13 0 29 4 24 5 27 4 26 7 Inches of mercury NOTE kPa and Bar are absolute pressure Used by permission of DuPont Fluoroproducts psig The numbers in parentheses the reading on the manifold gauge GLOSSARY OF TERMS A coil An A shaped evaporator normally installed in the plenum chamber of a central air conditioning unit accumulator A small storage cylinder placed anywhere in the suction line It collects liquid refrigerant and allows it to vaporize before getting into the compressor air infiltration Penetration of the outside air into a refrigerated or an air conditioned area ammeter A device to measure the flow of electrical current in a circuit ampere The standard of measurement for the amount of current flowing past any given point in an electrical circuit atmospheric pressure 14 7 Ib in pressure exerted from the whole mass of air surrounding the earth upon different objects at sea level automatic expansion valve AEV A pressure controlled valve that controls the flow of refrigerant entering the evaporator axial flow fan A regular fan with blades perpendicular to its shaft moving air a
167. R 1 Disconnect the power supply 2 Turn the wall thermostat off 3 Remove the screws in back of the contactor that hold it in place There could be two three or four screws 4 Remove the contactor and disconnect the two wires to the coil 5 Set the ohmmeter on its lowest scale and touch the probes to the two coil terminals or the wires coming from it The meter should register a continuity reading If not replace the contactor or the coil Usually contactors are relatively inexpensive and it would not be worth the time to just replace the coil The cost to the customer would be about the same the points could go bad during the warranty period for the coil Save a callback and the trouble of explaining to the customer the difference between a coil and the contacts DOMT Mpm 15 O CONTACTOR A E i iii l M EIERE AN Hr CeO in Hi Ga een ieman Hom W mres Carrpib4 Lis Ynllaga run Was emer fires Carrpisa Ji var mma edet all un Ferrea na AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 247 6 Check the contacts carefully If there is any pitting or discoloration on or around the points replace the contactor even if it is working These are signs that the contactor will not go much longer without becoming defective Figure 152h Figure 153 thine te ag Older circuits may us
168. R 12 charge Run equipment and adjust charge until optimum operating conditions are reached If a flushing technique is being used repeat steps 1 2 3 5 6 and 7 three times Run the system with R 12 refrigerant twenty four to forty eight hours after each time Filter drier replacement is not necessary during the flushing procedure TYPES OF OIL USED WITH SUVA BLENDS When performing any retrofit you should always remove as much of the old oil as possible before adding the new lubricant The most important thing is to use only the product or type recommended by the compressor manufacturer The type of lubricant is determined by the type of refrigerant HFC refrigerants 134a and HP62 will require a polyol ester lubricant for stationary units But cars with R 134a systems use polyalkylene glycol HCFCs like SUVA MP series or HP80 or 81 require alkylbenzine 408 SUVA HP REFRIGERANTS SUVA HP refrigerants SUVA HP 62 80 and 81 are odorless and nonflammable at atmospheric pressure in temperatures up to 176 F 80 C They should not be mixed with air when testing for leaks They can be used for retrofitting of existing nonflooded systems using R 502 They re suitable for both medium and low temperature equipment such as transport refrigeration ice machines and supermarket display cases SUVA HP62 is intended primarily for use in new equipment Although we have provided retrofit guidelines for this product HP80 will usually pr
169. RIGERATION REPAIR MADE EASY 387 If the valve and thermistor pass these checks you re ready for the next step Check system performance Reconnect the valve and thermistor to the 24 volt power source Switch the volt ohmmeter to the 50 volt scale and connect its leads to the valve terminals see fig 212 If the valve operates correctly the volt ohmmeter reading will fluctuate as the valve modulates refrigerant flow The reading will drop each time droplets of liquid refrigerant reach the thermistor It will rise when dry suction gas is at the thermistor During normal operation the volt ohmmeter reading may be as high as 20 volts and as low as 5 volts At peak loads the ohmmeter should register a reading within the 15 VAC to 24 VAC range It may hover at some point between 15 VAC and 20 VAC If the reading stays between 15 VAC and 24 VAC for more than 5 minutes and the system does not become satisfied the valve is probably not opening properly It may be restricted by solder or other foreign particles At low loads the readings will fall between 5 VAC and 14 VAC and may hover at some point If it stays in this range for more than 5 minutes and the system is not at minimum load conditions the valve may be overfeeding the evaporator To pinpoint either of these problems attach a gauge manifold to the system and check the high side and low side pressures If after conducting the volt ohmmeter tests you still haven t found a pr
170. Routing Wires to Location Through this hole drop a weighted strong cord and snag cord with hooked wire from basement On basementless houses drop cord through hole in ceiling and into wall and snag it at the thermostat location Attach thermostat cable to cord and pull it through hole in wall so that six inches of cable protrudes E z Wriar Courtesy of White Rodgers Division of Emerson Electric Corporation HOW THERMOSTATS WORK There are four basic types of thermostats in common use 1 Thermostats that operate on the principle of the different expansion rates of different metals like the in line thermostat mentioned in a previous chapter See fig 169 A BIMETAL THERMOSTAT Low Empanginn Metal _ When two alloys with different expansion rates are welded together one will expand more than the other when heat is applied This will make the metal flex causing an electrical circuit to open or close Tanp Decrease High Expansion Hetal Figure 169 2 Thermostats that operate on the principle of gas expansion by heating See fig 170 Tampersture 1 As the thermostat diaphragm flexes with the expansion or contraction of the refrigerant within it it causes an electrical GERE circuit to open or close Temperaturm Decrease Figure 170 260 3 Thermostats that operate by using a thermister Thermister resistance changes as temperature changes causing an increase or
171. S ABOUT DIAGRAMS 194a 194b and 194c What is the function of the transformer in these diagrams To activate the indoor fan relay coil and the control relay coil What is the function of the control relay coil To control the operation of the condenser fan motor the crankcase heater and the compressor What contact s close when the control relay coil is energized The normally open contacts in the compressor and the condenser fan circuits When is the crankcase heater energized Since the contact in the crankcase heater circuit is normally closed the heater is energized when the control relay coil is deactivated How many controls are there in the compressor circuit Four a normally open control relay contact a high pressure control a low pressure control and an internal thermostat What will happen if the transformer becomes inoperative Only the crankcase heater will operate What will happen if the selector switches on the wall thermostat are placed on COOL and ON positions The internal fan motor will run constantly and the compressor will come on as long as the low pressure control the high pressure control and the wall thermostat in the control relay coil circuit are not satisfied What causes the operation of the indoor evaporator fan The ON AUTO switch on the wall thermostat and the indoor fan relay coil Is this a schematic wiring diagram for a heat pump No because there is no reversing valve in the circ
172. TH 2 DTC ODT 1 DFT ODT 2 DFR RVR RC IFR HR 1 HR 2 HP LLP IFM DTC NO NC DFR RVS OFM Relay Contactor Crankcase Heater Thermostat for heater Thermostat second stage heating in wall thermostat Defrost timer coil Outside Thermostat Sensor for Stage 1 Heating Defrost Thermostat Outside Thermostat Sensor for Stage 2 Heating Defrost Relay Contact or Coil Reversing Valve Relay Relay Coil Internal Fan Relay Stage 1 Heating Relay Stage 2 Heating Relay High Pressure Control Low Pressure Control Internal Fan Motor Internal Thermostat Q eel Defrost Timer Contact Normally Open Normally Closed Defrost Relay Contact Reversing Valve Switch Outside Fan Motor Condenser NO Normally Open Coil Contact NC Normally Closed Coil Contact Defrost Cycle is terminated when DTC contacts open The defrost timer is energized for ten minutes A TYPICAL SCHEMATIC WIRING DIAGRAM OF AN AIR CONDITIONING UNIT USING A HEAT PUMP AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 345 EXPLANATION OF THE DIAGRAM ON PAGE 344 The diagram on page 344 is a typical schematic wiring diagram of a heat pump It operates on three different circuits The compressor works on a three phase 460 VAC 60 Hz circuit and its operation is controlled by a contactor operating on 230 VAC The 24 VAC circuit is controlled by the wall thermostat When there is a need for heating the thermo
173. Thermostat Hot Gas Solenoid Ohms BN VC TT Water Inlet Bolenoid 50 ohm 00 onam Hnster Switch nin Tnermostat tea Cutter Grid 11 Tranms ormer Figure 188a A TYPICAL SCHEMATIC WIRING DIAGRAM OF AN ICE MACHINE The following two pages illustrate this circuit in the cooling and defrosting harvesting cycles Note the path of current in each cycle NOTE In ice machine figure 188c when the evaporator thermostat is not satisfied closed power flows through the fan motor and pump motor not through the two solenoids This graphically illustrates the rule that ELECTRICITY ALWAYS FOLLOWS THE PATH OF LEAST RESISTANCE The fan and the pump motor circuits have very little resistance as compared with the hot gas and water inlet Solenoids which have a resistance of 200 O each NOTE In ice machine figure 188b the thermostat is open offering an infinite amount of resistance in that part ofthe circuit Power is now directed through the hot gas and water inlet solenoids since their combined resistance is no match for an open circuit Although the fan motor and pump motor are still in a live circuit they do not run or they run extremely slowly This is due to the fact that the components with the greatest amount of resistance in a series circuit consume the greatest amount of power in that circuit In a series circuit with components of different resistances the ones with the highest amount of resistance con
174. VAC receptacle expect a reading of 250 S Ground Texmdmais VAC between every pair of hot terminals Figure 182 HOW TO CHECK A RECEPTACLE FOR A CIRCUIT GROUND In a 110 125 volt receptacle one ofthe two top slots the hot wire terminal the smaller opening H and the neutral wire terminal the larger opening N and the bottom terminal G is connected to ground G See fig 182 1 Place one voltmeter probe in H the hot side terminal and the other one in N the neutral terminal The meter should register a reading of 110 125 VAC 2 Place one voltmeter probe in slot H and the other one in slot G The meter should register a reading of 110 125 VAC otherwise the receptacle is not grounded anda licensed electrician should be called to remedy the problem 3 Placeone voltmeter probe in slot N and the other one in slot G The meter should register a volt reading otherwise the polarity of the receptacle is reversed due to improper wiring which will have to be remedied by a licensed electrician In 220 277 volt receptacles the two top terminals are hot H The voltmeter should register a reading of 220 277 VAC between the two H terminals and a reading of 110 125 VAC should be registered between either of the H terminals and the ground terminal Otherwise the receptacle is not grounded In the schematic wiring diagrams the hot and neutral receptacle terminals are shown as L1 and L2 in a 220 277 VAC system the two hot term
175. WATER LEVEL Figure 1304 Ba float up ta raise water level AM ICE THICKNESS THERNICETAT 1 Rend rod up in te coe cambar rus eter bevel Bem rt cream to wer worm lowe 2 The Dor r cos and ra sensing bele datirmmnas the Teickreazs of the ka Coury a broad AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 191 REASONS FOR NO ICE PRODUCTION Water valve closed Evaporator thermostat inoperative or set wrong Water pump inoperative or clogged Cutter grid has open circuit Refrigeration system inoperative Mineral built up on the evaporator surface 7 Open bin thermostat Open electrical circuit to the compressor COMMON SEALED SYSTEM PROBLEMS Restriction Compressor failure Leaky hot gas valve Refrigerant leak gt SIGNS AN UNDERCHARGED ICE MACHINE 1 Donut shaped ice cubes 2 Hissing sound heard in the evaporator while running If ice cubes come out too thin or too thick the reason can be due to an out of adjustment or defective evaporator thermostat The evaporator thermostat should have a cut in temperature of between 31 F and 32 and a cut out temperature of 3 F to 10 F Sometimes the complaint is that the bin is full of ice and the machine will not shut off The amount of ice in the bin is controlled by a bin thermostat or a lever operated switch in the bin that will have to be replaced A linted condenser is a common r
176. When its temperature drops it contracts causing it to occupy less space due to the rule of expansion and contraction Humidity The amount of water vapor in the air Air consists of several gases one of which is water vapor The higher the amount of vapor per cubic foot the higher the humidity The average comfortable humidity at 75 F is 50 As the humidity increases it creates discomfort and as it drops it feels drier In desert areas humidity is sometimes under 3 and that is why air feels so dry and uncomfortable Figure 132a shows an imaginary body of fifty grams of air holding fifty grams of water at 50 F constituting a 50 humidity As you see in figure 132b if the temperature of the fifty grams of air is raised to 75 F it will expand a larger volume of air holding the same fifty grams weight of water in it stays constant causing the ratio of water to air volume to change causing the humidity to drop to 33 Saree rhe Gi Ob gee oie zi abr Eus za high beep ee ratip of water ip oam mirni ee D burem 58 cf watar 40 mmm nf weber 4 in in 97 wmm nf air 50 qus af air RULE I AS AIR IS COOLED HUMIDITY INCREASES RULE Il AS AIR IS HEATED HUMIDITY DECREASES In air conditioning air is cooled as it is forced through a cold coil or heated by passing it through a warm coil an electric heating element or over surfaces heated by gas flames The capaci
177. YSTEM WORKS In figure 16a when the timer takes the unit into the defrost cycle the three way solenoid valve becomes energized and diverts the flow of hot refrigerant into the evaporator bypassing the condenser The hot refrigerant causes the accumulation of frost on the evaporator coil to melt TEST YOUR KNOWLEDGE ON BASIC REFRIGERATORS AND FREEZERS What are the primary parts of a refrigeration unit fig 4a Where is the evaporator located figs 3 4 5 6 8a 9 11 and 5 What is a sealed system p 14 fig 11 What is the function of an evaporator pp 5 30 What is the primary function of a defrost timer pp 23 24 What are the most common troubles with defrost timers p 25 What happens when loose connections on a defrost timer fuse together p 25 What is the primary function of a thermostat p 25 9 What is a thermostat sensing bulb and where is it attached pp 25 26 10 What purpose does an overload protector serve p 26 11 Where is an overload protector located pp 26 27 fig 12 12 What is the role of a starting relay p 26 13 Which compressor winding s is are are energized at the instant a compressor starts p 26 14 How many windings are there in a compressor p 26 15 What is the suction port of a compressor connected to p 28 So go 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 AIR CONDITION
178. a relay automatically deactivates the reversing valve Additionally other primary controls relays contactors etc energize the compressor the condenser and evaporator fans 2 Asillustrated in figures 174 if expansion valves are used two will be needed in a heat pump Only one expansion valve becomes active at a time whether the unit is in the heating or cooling mode is installed before the inside coil and one is installed before the outside coil The pressure limiting type of expansion valves are best suited for heat pumps 3 Since the direction of refrigerant flow changes when a heat pump is used the installation of a bidirectional filter drier is necessary 4 Thefunction of check valves is to ensure that the refrigerant flows in the proper direction during the heating or cooling cycles One check valve controls the refrigerant flow in the heating cycle and the other one controls the flow in the cooling cycle When using a capillary tube in a heat pump a strainer must be installed at each end Because the flow of refrigerant can be reversed in heat pumps capillary tubes become an excellent control See fig 174b 266 HEAT PUMP IN THE HEATING CYCLE When the reversing valve is de energized it connects the inside coil to the compressor discharge line acting as a condenser and the outside coil to the compressor suction line causing the unit to heat See figs 103 and 104 As illustrated in figure 174 heat p
179. ain if the compressor terminals are unmarked This line can be determined by using a voltmeter to measure the voltage in the three power supply wires two by two until the highest leg is found Normally in a three phase circuit voltage in one of the power supply lines is up to 3 higher than the other two Figure 152b shows a three terminal contactor It connects directly to the three terminals of a three phase compressor A typical connection is illustrated in figure 178 below When a new three phase compressor is installed check the voltage between the three terminals If the voltage varies more than 3 check the terminals for a loose connection If the connections are OK check the power at the main fuse box If the problem is there call the power company to correct it before turning on the unit Figure 178 rh Ns Three hot line wires are connected to the compressor terminals through the contactor Three Power is connected to contactor terminals L1 L2 Por Supply and L3 When contactor coil is energized those terminals pass the power to the compressor through terminals T1 T2 and T3 Contacts If power reaches the compressor and it short cycles if no unusual pressures are observed to ATYPICAL WIRING HOOKUP indicate a restriction and the condenser is clean OF A THREE PHASE COMPRESSOR then the compressor has an internal problem and it must be replaced If the unit is equi
180. air pump to a point well below atmospheric pressure vaporization The conversion of liquid into steam by increasing temperature or reducing pressure or a combination of both volt The measure of energy electromotive force which pushes electrons through a circuit voltmeter An instrument for measuring voltage in a circuit watt The rate of work represented by a current of one ampere under the pressure of one volt a volt ampere After James Watt AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 431 water cooling tower A unit in which heated water is rapidly cooled by bringing it into contact with fan forced circulating air water cooled condenser A type of condenser which is rapidly cooled by the action of water flowing over or adjacent to its coil wax An ingredient in compressor oil When cooled enough it settles in a refrigerant metering device such as the capillary tube causing a restriction in the sealed system winding A coil of wire that produces a magnetic field when current is applied INDEX Brazing and flaring 68 Capacitors 89 90 91 Capillary Tube How it works 31 64 65 Test for restriction 178 Size and length chart 66 How to unclog 64 Central Air Conditioners 247 through 289 Charging Methods By using Ammeter 110 112 By using a charging Cylinder 111 113 By observing evaporator frost pattern 114 115 By gauge pressure 115 116 By using a charging chart 283 By high side 406 409 By name plate info
181. aky joint To do this the tubing must be held securely while cutting Use a small vice C clamps or Vice Grip pliers Then ream the inside of the cut to make it smooth Most tubing cutters have a reamer attached The tubing may also be cut with a fine tooth hacksaw thirty two teeth inch see fig 18 When using either method make sure that no chips or shavings remain inside the tubing Flaring couplings The flared fitting relies on the airtight connections of the fittings rather than brazing The fittings are a flared half union coupling and two female flare nuts They are retained on the tubing bya small flaring on each of the ends to be joined For this type of connection a different set of tools is needed from those used in making a brazed connection They are inexpensive and available almost everywhere in hardware and refrigeration supply stores See figs 24a and 24b ciE T3 8t cp Figure 24a Reduction Coupling Flared Connection E 1 These are the most pling commoncouplings TABLE OF COMMON REFRIGERATION FLARE TYPE FITTINGS ta pie available for flared vla 1 2 Union connections They TYPE SIZES OF FITTINGS AVAILABLE OD pHi ee vr s sm che m Union Both ends same size x x x X Tee alloy to fit all sizes MM T of tubing Only Half Union pipe brass tubing is recommended E 90 Elbow for refrigeration bs icati Tee One end pipe applications i Reducing Joints Unions iid
182. al air conditioners 1 Regular finned evaporator as in window units consoles or split systems see figs 137 and 157 2 Slanted style evaporator coil used in split or console units see fig 159 3 A coil style evaporator which is widely used in split systems with plenum chambers See figs 163 and 164 The plenum chamber Fig 165 is the center of airflow inside the air conditioned area and it is usually installed in a closet The suction and the liquid lines are connected to the evaporator coil in the plenum chamber see fig 158 A blower fan draws the air from the conditioned area into the plenum chamber passes it through the evaporator coil and expels it back into the conditioned area through insulated metal or flexible ducts See figs 161 162 and 165 AnA coilorslanttype evaporator is used inside the plenum chamber Condensate water from either of these coils is collected in a drip pan underneath and evacuated by a drainpipe See fig 164 Central air conditioning systems use either capillary tubes or expansion valves On the outside the condenser fan forces airthrough the condenser to cool it Inside the furnace chamber see fig 158 an air filter see fig 149 is installed in the path of the return air where Figure 159 A SLANT TYPE EVAPORATOR Liquid line connection Suction line connection Condensate drain Drain pan A WALL MOUNTED EVAPORATOR USED IN A SPLIT SYSTEM EE
183. an ohmmeter as described in Testing the Defrost Heater 126 WATER LEAK UNDER THE UNIT The formation of a puddle of water under the refrigeration unit is a very common problem In figure 85 note that the suction line going into the compressor runs next to the capillary tube coming from the filter drier and condenser When the warm capillary tube is placed next to the cold suction line its heat is transferred to the suction line This causes the capillary tube to become cooler and the suction line temperature to rise at the same time The purpose of this heat exchanger is to help the capillary tube start cooling down on its way to the evaporator and to help the suction line to warm up on its way to the compressor Usually in residential and light commercial units these two lines are brazed together at the factory or placed together and insulated on the assembly line to form a permanent heat exchanger The suction line coming from A TYPICAL REFESGERATTATS x SFSTEM ln Figure 45 well tha Tec H etr capitan tube meal uicti line are separsizd Put them Back together mrzi wrap ther Ah d tape To form a hear exchanges 1 Heat 2 Condenaer 1 fan a Compresnr 5 Filter dier Capilary tube 7 Beiporator B Evaperatis the evaporator is cold when it is not insulated it causes condensation when coming in contact with surrounding warmer air T
184. antly Note that the evaporator may be covered with a heavy layer of soft frost An efficient compressor produces a layer of hard frost on the evaporator coil As more experience is gained the evaporator frost pattern will become very evident When a compressor is turned off the evaporator frost pattern disappears very quickly The frost on the accumulator disappears in few seconds when placing a hand around it An accumulator in a properly operating system is covered with hard frost HOW TO IDENTIFY UNMARKED COMPRESSOR TERMINALS Occasionally you will encounter some compressor terminals which have no markings or which may have been obliterated There is an easy way to determine the compressor C S and R terminals Here is how Set the ohmmeter on its lowest scale In figure 38 imagine the unmarked terminals as 1 2 and 3 Place the two ohmmeter probes on terminals 1 and 2 make a note of the reading 7 for instance Then place the probes on terminals 2 and 3 assume 8 Q and note it Finally take a reading between 1 and 3 assume the meter indicates 6 The highest reading between any two terminals means that the remaining one is the common terminal Since number 2 and number 3 terminals have the highest reading it can be deduced that number 1 has to be the common terminal Since it has already been noted that the reading between terminals 1 and 2 is 7 Q and the reading between terminals 1 and 3 is 6 the high
185. aphragm when there is a significant pressure drop in the evaporator evacuation Removing moist air from a sealed system by creating a vacuum with the help of a vacuum pump evaporator pressure drop The difference in pressure between the inlet and the outlet of the evaporator Pressure drop also occurs in a filter drier expansion valve A pressure operated device in a refrigerating system to create and maintain the pressure difference between the high and low sides evaporator Part of the sealed system in a refrigeration unit that converts liquid refrigerant into a vapor to absorb heat Fahrenheit The scale used by GD Fahrenheit on his thermometer which at sea level water boils at 212 F and freezes at 32 F farad The unit of electrical capacity the capacity of a capacitor called capacitance Because this unit of measure is too large capacity is usually shown in microfarads one millionth of a farad Symbol f or mf After Michael Faraday English physicist fittings Male and female connectors or adapters used in joining together the ends of tubing AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 423 flare A small funnel like enlargement in the ends of tubing enabling the flare nut to make an airtight seal flare nut One type of fitting which joins tubing after the ends have been flared and its companion nut has been fitted to the other tube to be joined flash gas That portion of the liquid refrigerant which eva
186. are that the saturated suction temperature of the coil is 30 F or less Air defrost should be utilized Install defrost timers For a room or case below 36 F the saturated suction temperature is approximately 26 F or lower therefore rapid coil frosting occurs A positive defrost system is required either gas or electric 11 19 A Long Free Draining Suction Line to the Compressor and Low Superheat This may lead to or add to flooding complications Follow good piping practice use an accumulator 11 20 TEV Superheat Setting Too Low Perhaps the proper superheat instruments were not utilized for the initial superheat seating You will need to adjust the superheat to the desired level and take a superheat measurement using the pressure temperature method see sec I 14 1 1 High Discharge Pressure Probable Cause Air or debris in condenser Dirty condenser Poor or no water flow Water supply to condenser too warm Condenser airflow restricted Wrong airflow direction through condenser Wrong size condenser fan motor and or blade Condenser fan motor not running or wrong rotation Remedy Purge the noncondensibles Clean the condenser Check water supply pump and strainers Check repair adjust condenser water cooling facilities Clean the condenser Correct airflow direction Use right size components Find problem and correct AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY Probable
187. arge or an overcharge In any of the above methods a piercing valve must be installed on the discharge line and the suction line of the compressor Commercial units already have service valves installed Instructions on installation of piercing valves are provided with the valves a Connect a refrigerant tank to the compound gauge and to the valve as shown in fig 78 and leave all valves closed b Connect a clamp on type ammeter around the line going to the run or common terminal on the compressor Turn on the unit Turn on the access valve Turn on the refrigerant tank Turn on the compound gauge and watch the ammeter As the system is being charged the amperage will increase When it reaches the FLA amperage indicated on the nameplate of the unit the system is charged with the correct amount of refrigerant Immediately close the compound gauge valve the piercing valve and the refrigerant tank Replace the cap on the piercing valve Use a little Teflon tape on the threads to prevent a refrigerant leak HOW TO PUT REFRIGERANT INTO A CHARGING CYLINDER Acharging cylinder is a tool that provides the means to place a specific amount of refrigerant into a unit see p 112 It is a calibrated cylinder which can measure in ounces the exact amount as specified on the nameplate of the unit or in a AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 111 reference book mentioned on page 112 Before starting to pu
188. arged both the head and back pressures go up As soon as the desired back pressure is reached shut off the valve and disconnect the refrigerant tank from the unit 133 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY T E6Z S TSZ ECEC Cvlc C LET 6 S9T L TST EBET 8 ScT TYIT TEOT 6 6 SiL BCL TTL 69 649 99 L Vv9 9 979 8 1 0 GEOV EC8C TT8 CS9C 6 8St T6SE 8 8vc T8EE CEEC 9 9 O8TE CS8IC 8 967 L 86c OvOC 6 08 06T 6692 ETIT VLLT LCC 8 CVIT v9cc 86 TEST 801 Vvic 6S6T S66T ST8T 8S8l V 89l STITT ZSST 66ST SCOT 9 EVT O8vVT GEG CCET Q9ET 8S8 VTCT T8L CTIT 9 SIT OTL 9TOT O90T TV9 9 76 696 8 6 OF8 C Ss6 99S vtc8 vee vss 808 Ll6 CVS C6 006 OES DLL SIS 097 998 LOS SYL 058 96v OEL ves 33unV33dIW3l 1 JYNSSAYd LNV339I433H HOdVA Q31V3n1vs S 6vc 9 vec 0 9 90 S 6I O T8T T 69T 9 LST 8 9 JOT S6 866 06 8716 S8 078 08 041 SL coL OL 99 859 LLS 09 OZL SS 97 OS LSY 6t 9vv 8v 9tv Lv 9tv 9v LTY SU vv 86E EV Cv T 09 9 8S CLS L SS evs 5gs 9TS 6 8v OLY 90 Ost SEV 9tv viv cov 0 6 OLE 8 9 LSE OVE Sie SCE VTE VOE v 6c v8c Sc S9c 9 sc 8 T8 9 8L TLL OSL Tvl FCL TTZ 69 789 8 99 vs9 TVv9 ECS 9 0 0
189. ary A similar fluid can be made by mixing equal parts of gasoline and kerosene but it is not as easy to use as the commercially made product in a spray can There are two basic types of fans used in air conditioners the axial propeller flow and the squirrel cage radial flow Fan motors are very sensitive to line voltage A drop in voltage can cause a drop in the fan speed Pay particular attention to the fan blade pitch and shape when replacing fans Don t attempt to straighten a bent fan blade as good balance and vibration free running are nearly impossible to achieve Always replace a defective blade Fans move air by creating above atmospheric pressures positive pressures on one side of the blade and below atmospheric pressure negative pressures on the other side to force air out or draw air in This of course is accomplished by the pitch the twist in the blade and the direction of rotation of the shaft Occasionally a blade develops a small crack especially in units with cast aluminum blades The defect is easily recognized by the high pitched noises the fan makes while working AN AXIAL FLOW FAN Figure 140b Figure 140c ALLEN WRENCHES Figure 140a Courtesy of MALCO Products Inc 234 INSTALLING WINDOW UNITS All window units must be installed in a way that the rear is seated about one fourth inch lower than the front to allow condensate water to drain to the outside A small carpenter s level will help to a
190. as described earlier and in figure 80 If there is no service valve on the suction line connect a piercing valve and leave it closed d Connect the charging cylinder to the gauge manifold and to the piercing valve as shown in figure 80 and leave it closed e Turn onthe unit f Turn on the piercing valve the compound gauge and the valve on the charging cylinder until the Freon in the charging cylinder gets to zero on the scale of the charging cylinder Then 114 When installing a piercing valve tighten the screws gently and evenly Do not overtighten Also be careful when removing the manifold gauge lines Any movement of the valve on the tubing may cause a leak All this information Shut off the charging cylinder valve Shut off the piercing valve and the valve on the compound gauge Remove the compound gauge hose from the suction line Remove all of the hoses and put the cap on the piercing valve after wrapping its threads with Teflon tape is given in the instructions with piercing valves Be sure to read it Dimgckmarvm Barricm Val A Buckie Gereiae Valve Commercial units can be charged by the high side method Connect the manifold gauge to a refrigerant container never use a disposable container with this method as it may explode Then connect the gauge to the suction and discharge service valves Ce ner Testa gy mi Ewa Ok PETERR F aei Talva L Fier
191. at Stuck light switch Leaky door seal No air circulation around unit Linted condenser coil Too much warm food loaded at one time Kitchen too warm Improper refrigerant charge Door opened frequently Defective fan motor Defective or incorrectly set thermostat Check fuse or circuit breaker Check outlet Call power company if there s low or fluctuating voltage Replace cord Test and replace if necessary Replace if no current passes through Check and replace if necessary Also check for loose or broken connections on thermostat and timer repair or replace as necessary Check and replace if necessary Push door switch to see if light goes out Repair or replace as necessary Check door gasket for leaks Adjust door or replace gasket Move unit or objects around it to create proper air circulation Vacuum lint and debris from residential units or clean commercial units with alkali and high pressure air or CO Advice customer that unit runs longer when the food compartment is heavily loaded Ventilate kitchen Check high and low side pressure and correct as necessary Advise customer to minimize the frequency of door openings Check and replace condenser or evaporator fans as necessary Check thermostat replace if necessary AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 119 PROBLEM POSSIBLE CAUSE REMEDY Freezer and fresh f
192. at and its bulb from the other end and the cord will follow When the old line is removed remove the cord from the old bulb and tie it to the new one With the new sensing bulb line carefully straightened pull the new bulb through with the cord and replace the screws securing the thermostat and its bulb AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 93 TESTING THERMOSTATS USING THE BYPASS METHOD In cases where the unit will not run at all and a defective thermostat is suspected simply by pass the thermostat to see if the compressor will resume running This method has a potential shock hazard so proceed cautiously and observe safety rules 1 Disconnect the unit from its power source 2 By passthe two thermostat terminals with a well insulated piece of wire with insulated alligator clips at each end The wire should be at least the same gauge as the original wire on the thermostat Make sure the clips touch no other part of the unit 3 Connect the power supply If the unit starts running the thermostat is defective 4 Disconnect the unit again to shut it off Remove the by pass wire and replace the defective thermostat amp aj cold T ES Caetrals wifes Biffareat deabanua f imma bra belle eee ee ben peices i i i Figure G 94 In commercial refrigeration there are primarily two types of thermostats in use 1 The bulb type see fig 68 In t
193. ater deposits on evaporative water cooled condensers acts as insulation and reduces the efficiency of the unit if it is not periodically removed from the system Water softening chemicals are used for water treatment to reduce water deposits The pH factor is a means of measuring the impurities in water The pH scale runs from one to fourteen one through seven is the degree of acid in solution and eight through fourteen the degree of alkalinity An ideal pH factor is seven to eight indicating no excess of acid or alkaline The water should be tested when its temperature ranges from 70 F to 80 F Certain chemicals can be added as needed to keep the water close to a neutral pH When servicing a water tower check the following a All lines exposed to possible freezing in cold weather should be wrapped with insulation and protected with heating tapes Clean strainer Check and clean air inlet screens if necessary Check pump Clean and flush Check tension of belts and tighten if necessary Check water for foreign objects such as leaves debris and algae Clean as necessary Check water level and adjust float if required Check spray nozzles and clean if necessary i Check water overflow drain Clean if required hoang 2 1 Figure 215 A COMMERCIAL HERMETIC WATER COOLED CONDENSING UNIT Water cooled motor Pressure motor control Liquid line service valve Relief valve Shell and tube type condenser
194. ature gt WN oe Some thermostats are used for heating by closing the circuit on temperature drop and some for cooling by closing an electrical circuit on temperature rise The ones used for comfort cooling in central air conditioning systems control both heating and cooling Basically wall thermostats are divided into two groups 1 Thermostats operating on line voltage 110 VAC 220 VAC etc 2 Thermostats operating on low voltage 12 VAC 24 VAC or 40 VAC generated by a step down transformer Some thermostats used in more sophisticated air conditioning units close circuits to operate shutters and dampers in the duct work to regulate airflow to the conditioned areas In the more elaborate systems solid state thermostats provide a high degree of efficiency in monitoring the ambient temperature without mechanical movement They operate on the principle of change of resistance in a thermister with the change in temperature Lately transistors triads and amplifiers are used in the more sophisticated solid state thermostats Whereas the operation of conventional ones depends on the physical qualities of metals and gases by their expansion and contraction AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 257 AIR CONDITIONER WALL THERMOSTATS Athermostat could be referred to as a command center for any refrigeration or air conditioning unit When used in air conditioning the temperature in the air conditioned space is
195. average ceiling height of eight or nine feet that measures seventeen feet wide and thirty one feet long an air conditioning unit of 11 000 to 15 000 Btu would be required m omn nnam x u m WIDTH OF ROOM IN FEET NOTE Units with less than the minimum Btu recommended will cool less efficiently and run longer Units that exceed the maximum Btu recommended will make the conditioned area too damp The Btu divided by 12 000 will equal the tonnage required 15 000 1 25 tons 12 000 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 277 TROUBLESHOOTING CENTRAL AIR CONDITIONERS Problem and Possible Cause Compressor Motor and Fan Do Not Start Circuit breaker off or fuse bad Reset breaker or check fuses Reset thermostat to lower temperature Short between Y R and G if unit starts the thermostat must be replaced Thermostat set too high Bad thermostat switch or wiring Loose connections Check wire terminals and tighten Check primary voltage 110 220 if power is there but no voltage on secondary wires 24 VAC replace transformer Bad transformer Bad compressor and or fan Check and repair replace as necessary Bad relay in control panel High pressure switch open Check or replace as necessary Check for dirty linted or obstructed condenser bad condenser fan relay or motor or bad high pressure switch Check for poor airflow through evaporator bad low pressure switch low Freon or
196. can cause a high superheat at the evaporator while simultaneously causing a low superheat at the compressor NOTE Aleaking valve stem packing is easily diagnosed by a frosted equalizer line if it is used on low or medium temperature systems Change the TEV before compressor damage occurs If using more than one TEV on adjacent evaporators make sure that each remote bulb is applied to the correct suction line for the evaporator it is to monitor See fig 198 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 371 11 6 External Equalizer Line Plugged or Crimped and Low Superheat The external equalizer line carries the evaporator outlet pressure to the underside of the TEV diaphragm to close the valve If that line is plugged or capped the valve will most likely be wide open causing a flooding condition In rare occasions internal valve leakage could cause a constant pressure on the underside of the diaphragm and consequently create high superheat If the external equalizer is plugged kinked or capped repair or replace it to provide an unobstructed pressure flow 57 6 line amp ramter thas J jina ar 2 O Clock 4 ar B O Clock 11 7 Cracked Diaphragm or Bellows Automatic Expansion Valves and Low Superheat A cracked diaphragm or bellows can cause floodback valve stays open if the adjustment cap is on and secure Replace the valve 11 8 System Contamination and Low Superheat See sec l 8 Two probabl
197. cator most of the machinery and recovery equipment used for R 12 and R 502 can be used to retrofit SUVA MP 39 MP66 HP62 HP80 and HP81 Insome cases even the same compressor oil can be used Check with the manufacturer of your equipment for specific recommendations Care must be taken not to cross contaminate when switching from CFC refrigerants to the new SUVA blends Be certain to use the new pressure temperature charts instead of the ones designed for the CFC refrigerants Several experiments have proven that only a small percentage of the expansion devices now in place TEVs AEVs capillary tubes etc will have to be replaced after retrofitting Sometimes superheat may require some readjustment Liquid line sight glasses can be used to determine the proper charge But in some cases bubbles will show even when the system is properly charged with SUVA refrigerant In which case other methods may be adopted to determine the proper amount of the new refrigerant charge Several compressor manufacturers provide retrofit instructions For instance Bristol has approved SUVA HP81 Copeland has approved and will warrant their compressors retrofitted with MP39 MP66 and HP80 if their retrofit procedures are followed Manitowoc Ice Machines are charged in the factory with HP81 Tecumseh uses alkylbenzene lubricant in its R 12 compressor and has approved HP81 so you needn t change lubricants when retrofitting with MP39 or 66 3 Figure 222
198. central air conditioning unit a visible sign of a linted evaporator or filter is that the suction line sweats and the unit becomes incapable of cooling If the unit runs for a long time frost will cover the suction line extending all the way to the compressor The suction line entering the furnace and evaporator housing is always heavily insulated This prevents warm air from coming in contact with the cold suction line causing a water leak on the floor due to condensation Generally in a split system the contactor drier and the compressor are placed in the condensing unit The transformer is installed somewhere close to the blower in the furnace housing The wall thermostat is installed in the conditioned area AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 253 The blower fan and the transformer in the furnace compartment are connected to a separate power source independently The fan and transformer in residential units require 115 VAC and the condensing unit is normally hooked up to 220 240 VAC The transformer reduces 120 volts to 24 or 40 volts of alternating current rarely 12 VAC to energize the contactor through a wall thermostat to control the operation of the compressor and the condenser fan Figure 162 illustrates another configuration of a typical duct system DUCE Fil Biscar A Evaporator Tm Aix i tx A DUCT SYSTEM In the cold seasons when
199. cessive pressures on the compressor during the next start up on this White Rodgers s A time delayed contactor Make the s connections this way apti ueduio 3u129 3 Jo UOISIAIG sie8pog eiluM Jo Asesino ZEN TT L 4n To achieve time delay connect field wiring to terminals Figure 152f designated A and B To eliminate time delay connect field wiring to terminals B and C 248 MINI PRESSURE CONTROL SWITCH A mini low pressure control is used in a central air conditioning unit to prevent extreme low pressures in the sealed system It is mounted on an access valve in the suction line mini high pressure controls are mounted on an access valve on the discharge line to shut down the system when head pressure reaches a dangerous level If a mini pressure switch is used it is wired in series with the low voltage line energizing the contactor coil These switches are not adjustable and differ from the manually adjustable pressure controls The mini pressure control acts only as a safety device TESTING A MINI PRESSURE SWITCH BYPASS METHOD Turn off the power Set the wall thermostat to AUTO and the coldest position Remove wires e and f from the minicontrol and bypass it by connecting the wires e and f together Turn on the power If the unit starts operating and the low side pressure checks correct the defective mini pressure control m
200. ches inside and against one wall of the larger tubing Using a pair of pliers crimp the opposite wall of the larger tubing until it fits snugly around the capillary tube Then clean and silver braze the joint as instructed earlier Because small tubing absorbs heat very rapidly be careful no solder gets far enough inside to block the opening of the small tube and cause a restriction COPPER OR BRASS ACCESS VALVES These are the strongest and most dependable because they are brazed on the tube instead of clamped on with screws Fit the correct size valve body number 1 on the tube and crimp the saddle tabs around the tube with pliers Then braze in place Apply heat from below being careful not to overheat the body Always sand the surfaces to be brazed and use flux When cooled insert the piercing shaft number 2 into the body being careful not to damage the O ring Insert the valve core number 3 into the shaft and screw into place with core driver number 4 Do not overtighten Screw on access valve cap number 5 Tighten securely with one wrench while holding the body nut with another Do not overtighten Figure 45f TWO DIFFERENT TYPES OF VALVES onina DH SHAFT FIBET VALVE INSTALLED IN TUBING Courtesy of Wagner Products Corp Miami Florida AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 67 PINCH OFF TOOL In refrigeration repairs a pinch off tool is used to seal off c
201. chieve this Since most walls are not thick enough for good support outside wall brackets are necessary to prevent the unit from falling see fig 139 Once the unit is in place rubber gaskets metal plates sealing compounds adjustable shutters filler boards and sponge strips can be used to make a weather tight installation Wall and window units are mounted inside a shell or casing that come with them See fig 141 The manufacturers attach adjustable shutters on the sides near the front to fill in the spaces to the edge of the window These shutters are extended to the inside edges of the window and secured to the window Then a filler board and or foam or rubber weather seal is used on the top where the window frame comes in contact with the shell AIR CONDITIONER SHELL IN PLACE READY FOR THE WINDOW UNIT When the unit is to be installed through a wall the opening must be large enough to accommodate the shell Large screws or long nails Figure 141 Figure 141 above shows a typical sometimes are enough to secure installation of an air conditioner shell it in the wall without the use of ready for the window unit Notice the outside support brackets if the wall rubber seal and extension panels around the unit to prevent air leakage Caulking is thick enough After adjusting the for small gaps may also be necessary shell for its one fourth inch slope i to the rear slide the unit into professional Caulking
202. cimg Walva Cm Ji T j r Fresk Few Gs beta take Evaporator 0 Thermi sior 1 UU Br Frim Foai Can p Tne S J n When Pes miem 5 proper DINE OE E vise d ries Fi e as shown in figure 80a Using a service wrench turn the stem on the discharge service valve all the way clockwise with the refrigerant container upright See figs 101 and 102 Run the compressor no longer than a few seconds just enough to build a pressure in the refrigerant container about 35 to 40 psi above the pressure in the condenser Turn off the compressor and turn the refrigerant container upside down toallow liquid Freon flow from the cylinder Read the printed instructions on the refrigerant cylinder for the type of Freon you are using first Turn the stem on the discharge service valve counterclockwise until you hear a gurgling sound which means liquid refrigerant is flowing into the receiver Read page 117 before using this method AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 115 CHARGING THE UNIT BY THE EVAPORATOR FROST PATTERN METHOD This method of charging is used where the evaporator can be readily seen such as in manual defrost units cycle defrost units and most commercial units where evaporator temperature is designed to be below 32 F In residential frost free units where the evaporator is covered removal of the cover would be too time consuming to use this method a
203. city of compressor Check for obstruction in air passage and dirty filter Check for dirty filter restricted air passage open exhaust door dirty fans condenser and or evaporator Lubricate fan motor Check for proper fan blade s or blower wheel be sure blade or wheel is not binding Check for a short in the fan motor Voltage should not be lower than 10 of that shown on nameplate Seals missing or improperly located Doors or windows open Check for restriction in sealed system loss of refrigerant or low voltage Check dimensions of area to be cooled and Btu rating of unit Advise customer of proper unit for area Check for proper voltage Reset thermostat instruct customer 280 Problem and Possible Cause Bad thermostat s Unit restarted too soon Faulty fan motor Sensing element improperly located Defective compressor or attached components Evaporator Has Excessive Frost Buildup Outside temperature below 70 F Sensing element improperly located Faulty thermostat Insufficient airflow Faulty unit Fan running too slow Unit noisy 1 Loose parts or mounting 2 Faulty compressor Circuit Breaker Tripping or Fuses Blowing 1 Faulty wiring 2 Restarting too soon 3 Wrong fuses or circuit breaker 4 Incorrect voltage Remedy 3 Check defrost thermostat in heat pumps and wall thermostat Advise customer to allow two to three minutes for pressure to equalize
204. clean them thoroughly Clean the inside of the piece of tubing being used as a connector flux the joint areas center the short piece of tubing over the joint and braze it During the preparation for charging a unit a few drops of a liquid chemical leak detector can be placed in the inlet hose before connecting it to the compound gauge manifold Follow the manufacturer s instructions on the package When the system is charged and resumes running in case of a leak the substance appears as a red ring around the hole as it escapes with the refrigerant making the leak easy to find Repairing a Leak in Copper Tubing 1 Connect piercing valves if there are no access valves in the system and discharge the system leaving the valve open 2 Cleanthe puncture with sandpaper and wipe it with a rag soaked in acetoneto remove all contaminants Epoca amp peak 8 bomuld to repar leaks on from the area to be silver brazed alumi ram rsaperators and comdensers is ideal for joining add rmetal In rmetal pert Epca L esk wil hye shear henh excess oof LDU psl Be thorou g h in this ste p within thirty minites aiem otherwise the solder will not b within pn Four alter regia adhere properly m Seal the hole by silver brazing 4 Whenthe leakis sealed replace the filter drier see fig 76 and connect a manifold gauge to the valves and recharge the unit with t
205. compressor crankcase heater energized As long as there is power to L1 and L3 What controls the operation of the indoor fan and how is it wired It is wired to a separate power source inside the building and its operation is controlled by the wall thermostat and a fan relay AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 343 The following is a typical example of troubleshooting by the voltmeter method It illustrates the expected readings as the probes touch different parts of the circuit Any interruption or short can be detected when compared with the expected readings ETE Trang ormaz Cwarload Prolectes The Tos Cutter Gri DoE as EST Evaparatus Thereosrtak FOR THESE READINGS ASSUME THAT THE MASTER SWITCH BIN AND EVAPORATOR THERMOSTATS ARE CLOSED UNLESS OTHERWISE INDICATED VOLTMETER PROBES PLACED ON E L1 and L2 E M and N ole DandC D and C Evaporator thermostat open EandF E and F Fan motor burnt out OandJ JandC AandB A and B O P burnt out and disconnected K and L Transformer inoperative G and H G and H Bin thermostat open j VOLTMETER READING READING SHOULD BE 115 VAC voltage reading 0 reading voltage reading voltage reading voltage reading 0 voltage 8 5 volts voltage reading 0 voltage 0 voltage 0 voltage voltage reading 0 voltage 0 voltage voltage reading 344 LEGEND CR CH TH 1
206. compressor when the temperature drops parallel circuit The connection of separate parts in a circuit so that all positive poles are connected to one conductor and all negative poles connected to another plenum chamber In a central air conditioning system a housing that holds heating and cooling elements and a system of mechanical ventilation from which temperature and sometimes moisture controlled air is forced into the conditioned area s pressure control A safety device that connects and disconnects the power supply to the compressor and certain other components depending on the unit as pressures change in the sealed system pressure drop Sudden decrease in pressure purging The process of removing moisture from a sealed system This process allows a less than full charge to circulate and flush out the unwanted vapor and moisture AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 427 receiver A cylindrical container in a sealed system for storing refrigerant refrigerant Any of a class of nonflammable hydrocarbons containing fluorine used in refrigeration systems refrigeration The cooling of a space or object below ambient temperature relay An electromagnetic device that normally functions as a switch to energize or de energize specific circuits resistance To oppose restrict or govern the flow of current It is measured in ohms restriction partial Occurs when moisture gets into the sealed system and
207. control to open or close the circuit to the compressor series circuit The connection of separate parts end to end in an electrical circuit to form a single path for current series parallel circuit Having the structure of both series and parallel circuits service valve An access valve such as a saddle valve or piercing valve that allows entry into the sealed system for pressure testing recharging etc shaded pole motor A type of motor having a run winding but no start winding used only for light loads short A circuit with no load short circuit Unintentional contact between wires or components resulting in lowered resistance and excessive flow of current This may cause an overload A circuit with no load sight glass A device installed in a sealed system with a clear glass insert in its top for viewing the refrigerant to detect a deficiency or moisture in the system silver brazing The process of joining metals with a nonferrous substance with some percentage of silver using enough heat to bring it its melting point slant type coil A flat evaporator coil placed at an angle to the flow of air solenoid A coil of insulated wire that produces a strong magnetic field in its center when current passes through it solenoid valve A valve operated by a moving armature activated by an electromagnetic field used to control the flow of refrigerant or other liquid split phase motor A motor with two separate stator windin
208. cooled causing the head pressure to decrease Fans with variable speeds are also used to maintain the head pressure at a desired level by the amount of air blown through the condenser fins The more the air velocity is increased more rpm the more the head pressure drops The condenser fan is wired to the compressor run and common terminals through a pressure control switch The pressure control is connected to the compressor discharge side The switch within the control closes the electrical circuit to the fan when the head pressure transmitted to the pressure control through an access valve connection rises to a predetermined point Variations in fan speed may be obtained by using a solid state control which governs the voltage to the fan motor The more voltage the higher the fan speed and vice versa The use of positive head pressure regulating valves becomes necessary where the condenser is exposed to severely low temperatures 366 Waxing can be remedied by evacuating and recharging the system with clean dry refrigerant and the proper refrigerant oil recommended by the manufacturers suitable for the evaporator temperature requirements of the unit l 9 Undersized TEV and High Superheat Figura 19k p The valve orifice is too small starving the evaporator Use the following information to properly size the TEV Refrigerant type Evaporating temperature Pressure drop across the valve Desired load ASO
209. creating above normal pressure in the discharge line and the condenser Another reason for short cycling in a system equipped with a low pressure control is the occurrence of general low pressures in the suction line as a 172 result of an undercharged system a leak in the system causing loss of refrigerant In this case as soon as power is restored to the compressor the lower than normal pressure in the suction line drops to the cut out point causing the low pressure control to react and shut down the system Thus short cycling continues as long as the unit operates under this condition A low pressure control is connected to the suction line to shut off power to the compressor as soon as the pressure in the suction line drops below its predetermined setting As soon as the compressor is de energized the evaporator warms and pressure in the suction line increases causing the bellows within the control to expand and restore power to the compressor Sometimes the cut in and the cut out settings on the control are adjusted too close In which case as soon as the compressor is activated the pressure in the system drops to the cut out point and the low pressure control shuts the unit off in short intervals In this case the settings must be recalibrated See fig 93 SHORT CYCLING AND A LINTED CONDENSER OR DEFECTIVE CONDENSER FAN MOTOR When the condenser gets linted or when the condenser fan becomes sluggish or totally inoperat
210. ct the unit from the power source remove the evaporator cover and remove the wires from the two heater terminals 2 Follow steps 1 2 and 3 in the A Quick Termination Thermostat Check Using the Bypass Method 3 Connect the two alligator clips on the test light to the two heater wires Make sure the connections are well insulated and do not touch anything else 4 Reconnect power to the unit and turn the timer shaft clockwise with a screwdriver until you hear a click At this point the compressor stops working 5 Ifthe test light glows disconnect power to the unit and reconnect the heater wires to the heater terminals 6 Connect power to the unit If the heater begins heating check the termination thermostat and the timer and replace the defective part If the heater doesn t heat replace the heater AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 97 TESTING A DEFROST HEATER WITH A CLAMP ON AMMETER This simple method of checking the defrost system will benefit you the most after studying the chapter on Basic Electricity as this test requires some understanding of schematic wiring Defrost Timer Flus Type KClamnp on diagrams and the heating element ohm Ammetirer variation in different units You will need a clamp on ammeter to run this test HOW TO WORK WITH A CLAMP ON AMMETER By pushing a small lever the tongs of the ammeter are opened to slip around the wire to be tested If the readin
211. d and needs to be replaced Next turn control toward wet until you hear a click then check again for continuity If there is continuity replace the control Relative humidity in room must be between 20 and 80 the extremes in average control knob settings Check function of bimetal switch as you would on any refrigerator Unplug unit bypass pressure control switch with jumper wire connect power and if unit starts replace switch Check as in number 4 above Check head and suction pressures clear restriction as previously instructed in the refrigeration section Check power source with voltmeter Check for short or ground Check by bypassing relay Check by bypassing protector 282 Problem and Possible Cause 7 Dirty or linted condenser 8 Extension cord too long or wire gauge too light for load Compressor Runs But Fan Does Not 1 Defective fan motor 2 Defective fan relay Unit Operates But Doesn t Dehumidify 1 Defective fan motor Restriction in sealed system Poor air circulation Area too large Humidity too low Excessive Amount of Frost on Evaporator Poor air circulation Area too large Humidity to low Defective defrost bimetal Remedy Clean condenser coil and fins Place unit closer to a wall outlet or use a shorter and heavier cord Check for current to fan motor check for continuity in fan motor repair or replace as necessary Bypass relay if fan run
212. d restricts airflow 6 Inefficient condenser fan A fan that does not run or runs too slowly due to worn bearings or an internal short reduces or stops air circulation over the condenser fins and prevents the refrigerant from losing its latent heat and changing to its liquid state This causes the head pressure to rise and if not corrected the compressor will burn out CLEANING THE CONDENSER There are several cleaning solutions in the market suitable for condensers They are primarily alkaline or acid about the same price and about equally effective The alkaline is preferred since it is less destructive Nevertheless it should be cleaned up promptly if it runs off onto the flooring Additional care must be taken when applying these chemicals to the cooling fins of a condenser The condenser fan s may have to be covered to prevent moisture from entering the motor s Once the solution is applied the dirt grease and lint begin to boil and steam This indicates it is working After the solution is given a chance to work for a while it can then be easily removed with a high pressure stream of air Most technicians carry cylinder of CO carbon dioxide or nitrogen in their trucks It is an excellent tool to clean a linted condenser very quickly For cleaning condensers on residential units all you need is a good long bristled brush and a vacuum cleaner Very often especially in commercial units a failure to cool properly can
213. d the start relay See Figs 43 amp 44 The run capacitor is in the starting circuit too It helps the motor run smoother and more efficiently See Fig 45 To accurately check a capacitor use a capacitor tester like the one shown in Figure 66 Follow Figure A CAPACITOR ANALYZER Courses of Miimii Give POR Conn the instructions furnished with the instrument Use the same micro farad rated capacitor to replace one with another Never replace a capacitor with a lower rated one In the event an exact duplicate cannot be obtained one with up to a 10 higher rating is permissible 90 As example suppose 100 mfd capacitor cannot be found to replace a faulty one Any capacitor rated 101 to 110 mfd may work but never use one rated under 100 mfd All capacitors are labeled with their voltage and mfd rating The liquid used in some capacitors is bipheny dielectric fluid which is dangerous Do not attempt to open the shell or burn it In many air conditioners two capacitors are incorporated into one These capacitors are seen with three terminals One marked HERM hermetic compressor motor another terminal marked C common terminal and one marked FAN The common terminal is connected to both the fan motor wire and the compressor motor The fan terminal is connected to the second fan motor wire and the HERM terminal is connected to the second compressor wire see fig 65 There is a red dot or
214. d wiring Repair or replace as necessary Repair or replace light switch Train customer Food must cool to room temperature first Adjust thermostat Replace door gasket if necessary 120 PROBLEM POSSIBLE CAUSE REMEDY Refrigerator compartment too warm cont Unit runs all the time and is too cold Unit runs all the time and is too warm Unit cycles on overload Freezer alternately cools and warms Fresh food compartment gets too cold Reduction of freezing ability of the unit Accumulation of ice on finned evaporator No or poor airflow from freezer to refrigerator Defective thermostat Thermostat bulb not in contact with evaporator Accumulation of ice on the evaporator surface Low amount of refrigerant Defective overload protector Defective starting relay Defective compressor Low line voltage Defective condenser fan Extension cord undersized and too long Restriction in capillary tube due to moisture in the system Cold control knob set too high Defective airflow heater Broken or defective airflow control Object stuck in airflow control causing it to remain open Obstruction in capillary tube by accumulation of wax Defective timer Defective defrost heater Defective thermostat Damper should open If not replace it Frost free units cool by this method Test thermostat replace if necessary Fasten bulb to evap
215. decreased to 24 VAC to activate the indoor fan relay coil which in turn activates the compressor the internal fan motor and the condenser fan motor n order for this to happen the cool switch and thermostat must be closed Low Frese Contre Figure 194b Ronarrod Bale po T Control Puaprmnaper Co EE Ca aa 7 inb 12 00 ign J Thurmnstat Preegers Control tntarzal Aotor Malas a formally open Lu CmmErul Belay Tomine Pan Hele MES 5 Cipsa Damas Mamtsr Wall Thermagtmt lait al Pepin fuir im 85 Ae Cool K Low Pressure i Bertca control Contin sala SS Wall Tharmortat Deitch ES Imdcog Fan Bmlay Coll to Intarna ai re nic 7 TherFmosEkE Inside Fam Belay Peel j Internal Fan Horor i contre belay Contact Fas Re A Heater Conk Toga Cage Healer a a Figure 194c Note the different paths in which the current travels in each of the diagrams When the thermostat switch is ON the indoor fan relay coil is energized and activates the internal fan motor NOTE The normally open NO contacts close and the normally closed NC contacts open in the 220 VAC circuits when the control coil s is are energized in the 24 VAC circuits Cantrul Haley Cet De p d 334 10 11 12 13 QUESTIONS AND ANSWER
216. denser feels cool to the touch the problem can be a restriction or a complete loss of refrigerant Add refrigerant to the system If the temperature rises throughout the condenser the problem is a leak Otherwise there is a restriction in the system If the last pass of the capillary tube drier or the condenser feels warm the problem is a leak If there is a restriction in the system replace the drier evacuate and recharge the system If there is a leak locate and seal the leak replace the filter drier evacuate and recharge the system AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 179 INSTALLING PIERCING VALVES AT THE LOCATIONS SHOWN BEFORE TESTING FOR A RESTRIC TION Figure 125 180 CAUSES OF HIGH HEAD PRESSURE Different types of refrigerant produce different head pressures In air cooled condensers a normal head pressure should correspond to a temperature of about 30 F higher than the temperature of the air passing over the condenser In the case of a water cooled condenser the head pressure must correspond to a temperature of 20 F above the temperature of the return water see fig 87 considering the type of refrigerant being used Keeping these rules of thumb in mind you will have a general idea what head pressure to expect When the head pressure goes higher than normal the cooling efficiency of the unit will drop as most of the heat does not dissipate from the refrigerant by the time it leaves the condense
217. denser side is equipped with a slinger ring see fig 138 It picks up the excess water from the drip pan and slings it through the condenser coil to further aid in its cooling as well as helping to eliminate the condensate water THREE 5PERD SHADED POLE FAN MOTOR The fans in central air conditioners circulate the heated or cooled air to individual rooms through air ducts in the ceiling or floor These fans may be installed inside the house as in split systems see figs 156 157 and 158 or in a self contained unit where they draw the air in from one side and expel conditioned air from the other See figs 137 148 and SHADED POLE FAM BOTOA SCHEMATICS 156a Many of the motors use a capacitor to run They should be lubricated once a year with an oil designed for them Fan motor oil obtainable from refrigeration supply dealers is rather thin as compared to ordinary motor oil AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 237 Sometimes fan motors begin to fail due to an internal short worn shafts age etc They operate slower than they should and do not provide enough air circulation through the evaporator coil This becomes evident by the accumulation of frost on the evaporator fins and a sweaty or frosted suction line The two most popular types of fan motors are the permanent split capacitor PSC motor and the shaded pole motor a The permanent split capacitor motor costs a little more but it is much mor
218. differential adjustments on the low pressure control 1 The corresponding pressure for R 12 at 35 F on page 133 The Temperature Pressure Chart is 32 6 psi This will be the cut in setting 2 Since the temperature of the evaporator should always be kept 20 F below the desired refrigerated ambient temperature to determine the cut out setting on the low pressure control 35 F 20 F 15 F 3 Refer to the temperature pressure chart to find the corresponding pressure at 15 F for R 12 Convert the 15 F to pressure which will be 17 7 psi According to step 4 above 32 6 17 7 14 9 psi will be the differential adjustment By setting the differential adjustment the pressure control will cut in at 35 F and cut out at 15 F 4 Using ascrewdriver turn the cut in screw until the cut in needle indicates 32 6 psi 5 Turn the cut out screw until the cut out needle indicates 14 9 psi Now the walk in cooler temperature is set to be kept at about 35 F The pressure control will cut in at 35 F and cut out at 15 F HOW TO CHECK THE LOW PRESSURE CONTROL First shut off the unit and remove the control cover to expose the switch Then connect a test light with alligator clips to the two wire terminals in the low pressure control Now connect the compound gauge to the suction line service valve and restart the unit as the unit must be running when performing this check Watch the test light and compound gauge while closing the liquid line ser
219. draining suction line to the compressor TEV superheat setting too low n AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 359 l CAUSES OF DISCHARGE PRESSURE PROBLEMS High discharge pressure Low discharge pressure Fluctuating discharge pressure IV CAUSES OF SUCTION PRESSURE PROBLEMS High suction pressure high superheat evaporator outlet High suction pressure low superheat evaporator outlet Low suction pressure high superheat evaporator outlet Low suction pressure low superheat evaporator outlet Fluctuating suction pressure Figure 195 A TYPICAL HEAD HOW A CONDENSER PRESSURE PRESSURE CONTROL VALVE REGULATOR VALVE WORKS During normal operation condenser discharge pressure port 2 is closed and refrigerant flows through the condenser and ports 1 and 3 When ambient air temperature drops port 1 closes and 2 and 3 open allowing hot gas to flow directly from the compressor into the receiver In this way the head pressure is kept within the correct range 2 Air Cnala Haad Frmmere Demdenser Dnabrel Vale Solenoid Filtar Betel ar Driar S o 3u02 ODTV AsayNoD ATYPICAL SINGLE VALVE HEAD PRESSURE SYSTEM FOR UNITS UNDER 15 TONS ri iF DEP ho Tom ASOF h 360 V MISCELLANEOUS PROBLEMS Compressor starts but motor cycles off on overload protector Unit starts but short cycles Unit runs continuously adequately sized inadequate
220. ds p 387 What are the symptoms indicating that the tubing walls in a water cooled condenser is covered with sediment p 395 What are the possible causes of high amperage draw in a system p 382 What are the possible causes for a fluctuating discharge pressure pp 376 377 and 378 Can flash gas be detected by a sight glass p 360 Can a solenoid valve be used to increase the head pressure in cold seasons p 363 Explain how a crimped external equalizer line reduces the superheat p 371 SUBSTITUTING SUVA REFRIGERANTS FOR CFCS Introduction Chlorofluorocarbons CFCs have been used as refrigerants for over sixty years They contain all the desirable properties by being nonflammable low in toxicity noncorrosive noncarcinogenic nonpoisonous and have a compatibility with other materials However depletion of the ozone layer has been linked to the stability of CFC compounds coupled with their chlorine content Consequently CFCs are being phased out and SUVA refrigerant blends substituted This chapter deals with the introduction and handling of those refrigerants It explains step by step how to retrofit the existing units from CFCs to the SUVA refrigerant blends This chapter reflects the latest data from DuPont Fluorochemicals 400 SAFETY RULES FOR HANDLING SUVA REFRIGERANT CONTAINERS 1 Use safety glasses steel toe safety shoes and gloves when handling containers 2 Disposable contai
221. e TEV b Flash gas can also be detected by installing a pressure tap at or near the TEV inlet Take a pressure and temperature reading at this location If the temperature measured is above its saturation temperature taken from the pressure temperature chart then flash gas is present Or the liquid line pressure control can be connected to a solenoid valves installed at the outlet of the condenser to open when the head pressure in the condenser reaches a desirable level AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 361 l 2 Liquid Line Restriction and High Superheat A probable cause is a partially plugged liquid line filter drier If the temperature at its inlet is higher than at its outlet the drier is restricted Install a new filter drier as previously outlined An effective way of eliminating moisture from the system is to properly vacuum the system after installing a new filter drier before recharging The minimum pump running time increases as the size of the unit being serviced increases Be sure your lines gauges and hoses are as dry as possible before beginning Also keep your refrigerant oil container sealed from the atmosphere at all time Refrigerant oil has an attraction for moisture When it is left open the oil absorbs moisture rapidly In systems using capillary tube s a strainer is installed between the condenser and the capillary tube on the liquid line see fig 142 The purpose of the strainer i
222. e compressor start winding causing the winding to burn TESTING RELAYS WITH TWO TERMINALS See figs 46 and 13 Disconnect the power supply Remove the access cover in the back of the unit Remove the plastic compressor terminal cover Pull off the relay from the compressor and disconnect its terminals from the wiring 5 Inspect the relay terminals for burn discoloration and the lead wires for charred insulation If so replace the relay If not 6 Set the ohmmeter to the RX1 scale and zero the meter 7 Holding the starting relay in one hand with the TOP up place the ohmmeter probes in the relay terminals The meter should register a PWR AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 71 continuity reading Otherwise the starting relay is defective and should be replaced Turn the relay upside down and place the ohmmeter probes in the terminals The meter should register an open circuit reading Otherwise the relay should be replaced TESTING RELAYS WITH THREE TERMINALS Disconnect the power supply remove the compartment cover of the unit and remove the plastic cover Remove the relay from the compressor terminals and inspect the relay terminals for burn discoloration and the wires for charred insulation If so replace the relay Holding the starting relay with the top up touch one probe to the terminal that connects to the compressor run terminal and the other one to the terminal that connects to
223. e Cause 5 Faulty component Moisture Drips Inside of Room 1 Unit improperly leveled 2 Drain hole s clogged 3 High humidity Unit Does Not Work 1 No power Faulty wiring Bad start relay Humidity control When used also called a humidistat 5 Defective defrost bimetal If equipped 6 Defective pressure control switch If equipped Unit Short Cycles 1 Humidity control If equipped 2 Restriction in sealed system Low voltage Faulty compressor Faulty start relay Weak overload protector 281 Remedy 5 Check capacitors thermostats overload protector relays switches fan and compressor motor etc Unit should be one fourth inch lower at rear to allow moisture to run outside Clean drain hole s of debris Reduce door openings repair or improve sealing around unit and advise customer of any abnormal operating conditions Check power supply at wall receptacle check plug and service cord circuit breaker or fuse make sure circuit is not overloaded with appliances Be sure unit is wired according to its wiring diagram check electrical components for correct wiring and operation If all is in proper working order and unit still does not run check for faulty compressor Check start relay on compressor as instructed in section on relays Unplug unit set control on dry and check for continuity across the plug prongs If there is no continuity the control is ba
224. e Low Side during the Off Cycle Causing Low Superheat When the System Starts The remedy is to insulate the suction line and or equip the compressor with a crankcase heater 17 TEV Seat Leaks Liquid Line Solenoid Leaks or the Compressor Discharge Valve Leaks during the Off Cycle Causing Low Superheat When the System Starts All of the above cause the liquid to make its way to the low side of the system during the off cycle The low side fills up with liquid refrigerant and as soon as the system starts up again the liquid floods the compressor causing low superheat Remedy You will need to install a heating element around the compressor crankcase 374 11 18 Excessive Coil Frosting Probable Causes Blocked evaporator coil debris in the evaporator fins Incorrect fan rotation Excessive room or relative Case temperature too low Wrong evaporator pressure regulator setting set below 28 F saturation Faulty hot gas defrost solenoid Not enough defrost time Evaporator fan speed set low Inadequate automatic defrost Remedy Clear and clean evaporator See section Il 9 Provide sufficient dehumidification equipment relocate the unit or check usage Adjust thermostat or regulator Repair or reset EPR setting Repair or replace the hot gas defrost solenoid Increase defrost time Increase evaporator fan speed If there is no defrost cycle and room or space temperature is 36 F to 40 F chances
225. e a poor seal on one side of the door gasket proceed to the next step c Remove the top hinge and the door and place a metal washer on the bottom hinge Reinstall the door and follow step 2b to get a AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 101 good gasket seal A washer is placed between the bottom of the door and the bottom hinge to compensate for any slight bend of the hinge caused by the weight of the door When ordering a new gasket to replace an old one it is set in an angular pattern from being in the box If it is mounted in this condition the gasket will come out wavy instead of being straight To make it soft and pliable simply put it in a clothes drier or warm water for four or five minutes prior to installation It will then become easier to handle and provide a neat installation Wien eating the dacr hinges apply Triacugalan dapor ranp an the donr 13 bep mzani tor tigri piepsrky ciel ah the Aag HW rea irani of thes nor the doce may mman neri Start with the corners first when installing a gasket Place the next screws in the center between the corners and the next screws between the centers of the last ones and so on until all of the screws are replaced New gaskets may come with shims to improve gasket fit should the door be only slightly warped Cracked or broken compartment liners can be neatly repaired with a Fiberglas re
226. e causes of low superheat are 1 the pin and seat of the expansion valve wire eroded or held open by foreign material resulting in liquid floodback or 2 moisture freezing the valve pin in an open position If suspected inspect the moisture indicator sight glass for moisture contamination reading Heat the valve with a heat gun to melt the ice Clean or replace any damaged parts in the AEV or replace the entire valve Install a new filter drier 372 11 9 Evaporator Fan Blades on Backward or Motor Running Backward and Low Superheat Install fan blades correctly and or check motor rotation 11 10 Oversized Condenser and Low Superheat An oversized condenser on a system without a receiver can produce excessive subcooling of the liquid refrigerant entering the valve leading to a higher refrigerating effect causing the TEV to become oversized assuming the subcooling effect wasn t considered in the initial valve sizing causing low superheat or flooding of the evaporator To remedy this condition correctly balance the components in the system 11 11 Excessive Subcooling and Low Superheat Probable causes are 1 subcooling circuits in the condenser 2 liquid line heat exchanger 3 mechanical subcooling such as through valves fans water cooling towers etc or 4 a combination of the above Remedy by correctly matching the components to the system requirements 11 12 Poor Distribution through Evaporator Circuits
227. e electrical circuit if it reaches an unsafe temperature between 225 F and 250 F during operation Once the compressor cools to a safe temperature about 150 F it closes the circuit and the compressor resumes operation This is a circuit breaker that needs no manual resetting See figs 55 and 56 l TESTING AN OVERLOAD PROTECTOR USING AN OHMMETER 1 Disconnect the power supply Figure 55 2 Remove the plastic terminal cover on the compressor amp An overload protector used in residential units Testing an Overload Protector Pa An overload protector used in commercial units Figure 56 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 81 3 Remove the two wires connected to the terminals of the overload protector 4 Set the ohmmeter to the RX1 scale and zero the meter 5 Touch one probe to each of the wire terminals on the overload protector to get a reading of zero on the meter If not replace the defective overload protector Also visually check for cracks on the overload protector If there are any the protector is bad and it must be replaced Sometimes in spite of the fact that they test OK with the ohmmeter when they are cool they may have become weak and open the circuit once they are warm Il TESTING AN OVERLOAD PROTECTOR USING THE BYPASS METHOD A test wire with two alligator clips will be needed 1 Disconnect the power supply 2 Clipthetwo test wire alligator clips to
228. e energy efficient This type of motor is usually used in the better quality air conditioners It comes with a start and a run winding and uses a run capacitor wired in series with its start winding see fig 144 Normally if the capacitor shorts out and the house circuit breaker does not trip as soon as the fan comes on the fan motor will become extremely hot after a short period of running time and it will eventually stop operating hpre 144 b The shaded pole fan motor does come with a capacitor since power gets to the motor through a selector switch a low medium or high speed selection See figures 143 and 145 Power must go through a high resistance path for the low speed setting a medium resistance path to operate at medium speed and a low resistance path to run at high speed This type of fan motor is less expensive and not as efficient as the PSC motor To test a shaded pole motor simply connect the common wire and any other wire to a proper power source Air conditioners have two basic functions air circulation and cooling or heating Air circulation is made possible by the use of fans and blowers A shaded pole fan motor may have a number of speeds The number of wires coming out of a motor determine the number of speeds Two speed motors have three wires three speed motors have four wires etc see fig 143 To test the PSC motor fabricate a test cord as shown in figure 146 The illustration is self e
229. e evaporator drawn by the compressor suction power 146 The thermostatic type double temperature valve is very similar in operation to the thermostatic expansion valve with the difference that it only opens to let vaporized refrigerant be drawn by the compressor suction power when its sensing bulb perceives the need for cooling When the valve opens the pressure built up in the evaporator drops causing the temperature to go down In the solenoid type as in figure 97 an independent thermostat is placed in line before the expansion valve to operate the solenoid When the thermostat is satisfied the solenoid valve closes allowing no more refrigerant from the liquid line into the TEV valve Figure 97 ee Tei Soleceid i E Liquid Decal Courtesy of Eaton Corporation Controls Division CONTINUOUS LOW LOADS SERVICING TWO TEMPERATURE VALVES If the warmer evaporator is too cold the drop in temperature may be due to a bad valve adjustment too closely adjusted at too low a temperature To make an accurate adjustment on a two temperature valve take the following two steps 1 Turn the adjusting nut one half turn at a time and allow fifteen minutes between turns In this way the evaporator will be given sufficient time to respond Attach an accurate thermometer to the evaporator and watch the temperature changes until you reach the desired temperature For more accurate results instead of usi
230. e existing publications in this field this unique book has been written neither at the third grade level nor does it require a PhD to understand It is the essence of several years of experience containing the most up to date information and methods of troubleshooting and repairing commercial and residential refrigeration and air conditioning units By successfully studying this book and applying its techniques even those already working in this field can substantially increase their hands on repairing knowledge and technique For those who would like to pursue this profession as a sideline just to supplement their incomes they will find that as they begin to be known and become more and more in demand they find less and less time for their regular jobs and in a short time they will get into this profession full time and really generate more business they ever thought possible Considering the tremendous size of this market this is after all a profession that puts its practitioners in great demand worldwide Providing these services to the consumer in his home or business is the most rewarding Frequently a unit fails when the customer needs it the most Therefore a service call must be prompt and efficient This book is written in plain language coupled with hundreds of pictures and illustrations to make it easily understood The step by step troubleshooting repair techniques and charts in this book make the most complicated jobs
231. e fig 1 on page 352 Connect red and white wires together to energize the gas valve or the electric heater relay causing the gas valve the compressor for heat pumps or the electric heater in the furnace housing to operate Connect the red white and green wire together to energize the entire heating system see fig 3 on page 352 To test the wall thermostat for a heat pump reversing valve connections refer to page 352 for the proper connections TIME DELAYED RELAYS Wall units usually use capillary tubes and central air conditioners may use capillary tubes thermostatic or automatic expansion valves Since most air conditioners run on refrigerant R 22 the pressures in both the high and low sides are considerably higher than in the regular refrigeration units That is why the diameters of the tubing used in air conditioners are larger Because of the high pressures in the sealed system larger units use relays that are time delayed That means when the unit is turned on the time delayed relay takes a little longer to energize the compressor giving the high pressures in the system a chance to equalize This prevents the exertion of those high pressures against the compressor during start ups Due to the higher load on the compressors in these units the circuit breakers used in their electrical circuits must be no less than 20 amperes 20A time delayed 264 If the unit fails to run in the heating mode follow the same proced
232. e heating cycle of the unit heat is produced by a gas flame a warm coil or an electric heating element The thermostat activates a relay which in turn connects power to an igniter and a gas jet or to the electric element or energizes the reversing valve and the compressor in heat pumps covered on pp 265 through 271 256 That is the primary difference between the thermostat used in a central air conditioning unit and one used in refrigeration which has a sensing bulb attached to the evaporator to detect temperature changes and operates on line voltage instead of 12 24 or 40 volts When wiring these low voltage wall thermostats use number 16 AWG wire Use the next smaller size number 18 AWG for lengths under fifty feet WARNING Never connect the line voltage 110 220 to low voltage thermostats They should always be wired to the low voltage side of the transformer There are several reasons why thermostats and contactors in air conditioning units are preferred to operate on a 24 VAC or 40 VAC system instead of 110 or 220 simply because a low voltage system eliminates the danger of fire lowers the cost through lighter wiring components etc reduces chances of relay burnouts increases reliability since components requiring lower voltage have a tendency to last longer and require less maintenance 5 eliminates the shock hazard that is associated with a thermostat operating on 110 220 volts for those adjusting the temper
233. e installed in any position Care should be exercised that any rubber hose connections are always in good condition Condenser outlet hose connection tends to deteriorate due to the blistering of its inner wall by warm water thus restricting or even stopping the flow of water through the condenser Failure of valve to close off when the condensing unit stops may be due to improper valve setting adjustment For proper setting see the table figure 214b Another common cause for failure of valve to close during the unit shutdown period is air which has been trapped in the unit high side This can be corrected by purging the noncondensible gases from the condensing unit high side Air should always be purged both from the condenser water line and from the high pressure side of the refrigeration system The water regulating valve can be manually opened to aid in draining water from the system Two openings are provided in the spring housing through which a screwdriver or similar tool can be inserted Place the tip of the screwdriver under the spring pad and exert a force to oppose the spring force This will allow system pressure on the bellows side to open the valve and drain the water compressor does not have to be running thus the valve is manually opened without disturbing the setting previously established with the adjusting screw Normally no filtering is required When the water source contains hard particles such as sand the water
234. e measurement is vital Figure 110g KNOW YOUR SUPERHEAT 1 rigurant EXRHFRE m z 1 Measure suction pressure at compressor 66 5 psig 2 Add estimated suction line 1055 2 0 psi 3 The result is the suction pressure at bulb SUPERHEAT CHANGE If superheat on the TEV is readjusted the result will be the following A Increasing superheat will reduce system capacity B Decreasing superheat will add to system capacity To increase valve superheat turn adjusting stem clockwise To decrease valve superheat turn adjusting stem counterclockwise S 0J1002 O21V Ase11no5 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 163 HOW TO ACCURATELY MEASURE SUPERHEAT IN A SYSTEM USING A TEV WITH AN EQUALIZER Step A Determine the suction pressure at the evaporator outlet with an accurate gauge If there is no gauge connection a tee installed in the valve external equalizer line can be used Step B Refer to the temperature pressure chart p 133 for the refrigerant used in the system and determine the saturation temperature at the observed suction pressure Step C Measure the temperature of the suction line at the remote sensing bulb location This can be accomplished by a strap on thermometer or an electric device similar to an Annie or Simpson meter Be certain the spot chosen for measurement is clean to ensure accurate readings Step D Subtract the satura
235. e overload protector and starting relay from the three compressor terminals See fig 12 Set the ohmmeter on its RX1 scale and zero it Touch the probes to the compressor C and S terminals The meter should register a continuity reading Otherwise replace the compressor Touch the probes to the compressor C and R terminals to get a continuity reading Otherwise replace the compressor Touch the probes to the compressor S and R terminals to get a continuity reading If not the compressor is defective Touch one probe to the compressor housing and the other one to each terminal in turn In each case the meter should register no continuity reading Otherwise replace the compressor 58 COMPRESSOR MECHANICAL FAILURE Another problem leading to compressor failure is regular wear and tear The compressor runs without being able to create the necessary pressure difference in the system simply because the parts are worn This can be checked by using the pressure gauges With the compound gauge connected to the low side and the pressure gauge connected to the high side if the high side pressure reads lower than normal and the low side pressure reads higher than normal the compressor will have to be replaced as it has lost its compression efficiency Since it is unable to maintain the required pressure difference in the sealed system the evaporator temperature never reaches low enough to satisfy the thermostat causing the unit to run const
236. e separation of the L1 and L2 sides of the circuit by the blown fuse creating a potential difference The heater is a load A load is a device that converts electrical energy to useful work Any AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 299 load separates the L1 and L2 sides of the circuit whether it is operational or nonoperational due to the disconnection of power within itself such as a burnt and disconnected element in a heater When the probes touch the two sides of the heater it registers voltage whether or not the heater is operational When the probes touch the two terminals of the light bulb a voltage reading is registered because the bulb is a load If there is a short in the lamp socket through which current is bypassed the voltmeter registers no voltage because no potential difference is created In figure 181 with the switch turned off and its two terminals contacted by the probes the meter registers a voltage reading but when the other components are checked no voltage reading is registered because no power reaches any other component to create a potential difference With the switch closed ON when the probes touch the two terminals of the lamp solenoid heater fan or compressor the meter registers voltage The meter should register zero voltage when its probes are placed across a blown fuse With the power ON and the voltmeter probes touching the following points expect these readings 1 The two termina
237. e the Ez ei TREO PON plug type fuse with a screw z r3 SUCH AS A CONTACTOR base like a light bulb If you t USED IN A CENTRAL AIR see any discoloration or a CONDITIONER broken filament the fuse 4 must be replaced Potential ype Below USING A VOLTMETER TO 7 im CHECK A FUSE BOX Touching the probes at the points indicated should get the following results Between 5and6 220 volts AC 5and7 110 volts AC 6and7 110volts AC If not call the local power company 1and2 Ovolts AC 3and4 Ovolts AC If a voltage registers replace burnt fuse Vote the direction of current flow in the line voltage and low voltage circuits A step down transformer converts 110 VAC to 24 VAC The coil becomes energized when the thermostat closes the 24 VAC circuit creating a magnetic field in the contactor or relay coil causing movable contacts to connect with the stationary ones in the 220 VAC circuit At this time the compressor and fan motor will start operating The line voltage plugs are only symbols for power sources Time delayed relays come with thermal current protection devices to prevent abuse of the compressor start winding from frequent start ups Every time the coil is energized the temperature of its heating element rises and disconnects the COIL CONNECTIONS primary power until the coil cools As aresult the air conditioning system pressures will have time to equalize to prevent ex
238. e to the low side of the system Cool down the evaporator by shutting down the evaporator fan s or block off the airflow through the evaporator Wait until the suction drops down to at least 5 psi below the desired level Allow the evaporator pressure to increase by the bypass gas The spring load can be varied until the valve closes at the exact desired pressure HOW A HOT GAS BYPASS VALVE WORKS A hot gas bypass valve is installed in a system to prevent the frosting of the evaporator When the pressure in the evaporator drops below a desired level the pilot valve 2 opens causing the main valve 3 to open permitting sufficient amount of hot gas to enter the evaporator and prevent the evaporator from frosting AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 363 l 3 Improper Piping Design and High Superheat Excessive vertical lift of the liquid line could be a probable cause Generally for every foot of vertical lift using R 22 there is approximately 1 2 psi drop Flash gas forms in a system that has excessive vertical lift Make sure before the refrigerant flows up the riser it is subcooled by going through a heat exchanger enough to prevent it from changing to gas by the time it reaches to the top of the riser where pressure is decreased Usually subcooling 10 F is sufficient for elevations up to twenty five feet Be sure to check the manufacturer s data Also the liquid line may be too long too small or ha
239. e to wear and tear to make them operational again SIGNS OF A FROZEN TIMER If freezer compartment stays warmer than usual defrost heaters on and the unit won t run including the evaporator fan butthe compartment light turns on when the door is opened check for a frozen defrost timer Using a screwdriver turn the timer cam clockwise until you hear a click If the unit starts running replace the timer See fig 54m AGAUTION Never troubleshoot the electrical circuits while power is connected to the unit Always disconnect the power supply before touching any wire or electrical component AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 55 This quick electrical check for compressors that fail to start does not cover those compressors that operate with capacitors If you are checking a compressor with a capacitor s follow the same procedure after checking the capacitor s as outlined below If the capacitor is bad it must be replaced with one of the same microfarad mfd or mf rating IMPORTANT After disconnecting power from a unit discharge the capacitor first by shunting between its two poles with well insulated heavy wire before handling it If there is no exact capacitor replacement or a capacitor tester available you can make a compressor test cord that can test capacitors too See figure 34a and follow these instructions 1 Disconnect the unit from the power supply 2 Discharge the capacitor and remove
240. e valves contain a diaphragm control spring FS1 seat and the basic valve needle or ball The control spring above the diaphragm moves the diaphragm down this opens the valve The opposing force is provided by low side evaporator pressure FE and a constant body spring force FS2 this moves the valve to close During the off cycle evaporator pressure builds up and overcomes the spring pressure This keeps the valve closed until the next cycle Then the compressor quickly reduces evaporator pressure When this pressure equals the control spring pressure the valve begins to open The valve opens when evaporator pressure falls below the control spring setting This is the point or setting at which the valve opens See fig 116 When it is used to control the evaporator temperature it is mounted on the liquid line at the inlet of the evaporator to control the amount of refrigerant entering the evaporator By operating only on the low side pressure it is activated when the evaporator pressure drops At that time the needle valve automatically opens and sprays refrigerant into the evaporator until the evaporator pressure rises to a predetermined point This can only occur when the compressor is running and creating low pressure in the evaporator When the compressor is stopped and no more suction is 168 applied to the low side the pressure built up in the evaporator prevents the needle valve from opening This prevents the evaporator
241. eason for not enough ice production Figure 131 is a typical wiring diagram of an ice machine Please refer to the Basic Electricity section to get a better understanding of the illustration 192 ipi Rnjamrdd iw o Fuss 113 TEG Figure 131 Trantor HOW AN ICE MACHINE WITH A CUTTER GRID WORKS WHEN SWITCH OPERATING ROD IS MOVED UPWARD TO ON POSITION Compressor runs Condenser fan Runs Water pump runs and circulates water Cutter grid is warm WHEN ICE SLAB REACHES PRESET THICKNESS HARVEST CYCLE BEGINS AND THE FOLLOWING HAPPENS Compressor keeps running Evaporator thermostat is satisfied Condenser fan stops or slows Water pump stops Hot gas solenoid opens Cutter grid is warm Harvest cycle lasts one to two minutes UNIT RESTARTS FREEZING CYCLE WHEN SLAB IS RELEASED FROM EVAPORATOR AND CUTTING PROCESS BEGINS WHEN STORAGE BIN IS FULL BIN THERMOSTAT OPENS NOTHING WORKS Cutter Grid Remains On To obtain a service manual for any particular ice machine call the factory s 800 number hotline The manufacturer s name and factory location can be found on the nameplate The service manual contains photographs line drawings schematic wiring diagrams and troubleshooting charts to further explain operation and repair of that specific unit AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 193 ADJUSTMENTS TO CHUNKLET ICE FLAKERS The purpose of the water leve
242. eating until the conditioned space reaches the desired temperature at which time the thermostat shuts off the unit Since air is moved through the evaporator coil filters should always be installed in the path of the airflow to prevent the coil from becoming obstructed see fig 149 These filters should be cleaned regularly or replaced if cleaning is not practical Dust and dirt particles collect on the filter or on the evaporator coil if the filter is removed causing the unit to lose its cooling efficiency When air circulation through the evaporator coil is restricted frost builds up on it If the unit runs for some time an abnormal suction line sweating or frosting is evidenced which extends up to the compressor Courtesy of Honeywell DAMPER LINKAGE AN AIR FILTER uosuuor jo se34no5 As the linkage is actuated its up and down movement causes the shutter to open or close to assist in temperature Figure 149 control by regulating the flow of conditioned air The compressor operates continuously and the unit no longer cools These symptoms are often mistaken for an inoperative or slow evaporator blower The air filter is normally in the bottom of the furnace in the split systems and it is in the return air duct in the package systems see fig 158 1 Remove the screws holding the panel covering the plenum chamber Remove the panel 3 Pull out the evaporator and clean under the coil with a wire br
243. ection H compressor suction connection sjonpoJd Jo 9 1 centrifugal compressor might be thought of as a squirrel cage like blower motor As the impeller turns a vacuum is created at its center causing cold vapor to be drawn in It is then compressed and expelled into the discharge port through the sides caused by high rpm These compressors can be hermetic or externally driven and are used commercially See fig 30 A screw type compressor is similar in operation to a turbocharger It has two cylindrical vanes with deep spiraling flutes that mesh together like gear teeth The extremely high rpm of the vanes meshing into each other creates vacuum on one side and high pressures on the other causing refrigerant vapor to be drawn in from the intake port compressed and forced out through the compressor discharge port Screw type compressors are used in heavy commercial applications 50 A liquid receiver is a liquid storage tank used on larger commercial systems and on systems equipped with expansion valve or a low side float type refrigerant control explained on pages 140 through 170 See figs 33 and 118 Dh ater Terba Talya BL LT DHSEN CDIAPRESSOR XT A BELT DRIVEN COMPRESSOR Service valves disconnect from the compressor lt Befrigaramk Inlat a Figu re 31 Courtesy of Gates Rubber Company Liai Kiriti The high pres
244. ector d Evapural t Thermostat TYPICAL SCHEMATIC WIRING DIAGRAM OF AN ICE MAKING MACHINE IN THE ICE MAKING CYCLE Tress former HOW IT WORKS Ling De Esergired Lins Energized WHEN SWITCH OPERATING ROD IS MOVED UPWARD TO ON POSITION Compressor Runs Condenser Fan Runs Water Pump Runs and Circulates Water Cutter Grid is Warm WHEN ICE SLAB REACHES PRESET THICKNESS HARVEST CYCLE BEGINS AND THE FOLLOWING HAPPENS Compressor Keeps Running Evaporator Thermostat Is Satisfied Condenser Fan Stops or Slows Water Pump Stops Hot Gas Solenoid Opens Cutter Grid is Warm Harvest Cycle Lasts One to Two Minutes When the evaporator thermostat opens current flow has no easier path than through the hot gas and water inlet valves see page 292 Since the heaviest loads in the circuit consume most or all of the available voltage the power remaining in the line will not be enough to activate the condenser fan motor and the water pump motor as each have only a 50 value UNIT RESTARTS FREEZING CYCLE WHEN SLAB IS RELEASED FROM EVAPORATOR AND CUTTING PROCESS BEGINS WHEN STORAGE BIN IS FULL BIN THERMOSTAT OPENS Cutter grid remains on AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 323 Liss Da Enaergnire Lins Ernargirud Figure 189a ATYPICAL WALL AIR CONDITIONER with the switch in the off position Coarse aor a CApaditor Fan
245. ed in medium temperature refrigeration units such as supermarket cases residential and commercial refrigerators and display cases industrial and commercial chillers and automotive air conditioners It is nonflammable with low toxicity It has a boiling point of 15 F 26 C It is carried in 30 Ib and 123 Ib containers color coded light blue It is sold under different trade names such as Hydrofluorocarbon 134A HFC 134A HFA 134A SUVA 134A SUVA Trans A C automotive market INSTA CHARGE THROTTLING __ VALVE The Insta Charge fitting is a fast and safe method for charging liquid refrigerant through the low pressure side of an air conditioning or refrigeration system without damaging the compressor It converts liquid refrigerant to saturated vapor for fast entry It connects directly to the refrigerant cylinder valve Figure 220 Courtesy of Wagner Products Corporation Miami Florida SUVA Cold MP stationary refrigeration air conditioning market Formacel 24 Dymel 134A general aerosol market Dymel 134P aerosol pharmaceutical market At ambient temperatures and atmospheric pressure HFC 134A is nonflammable It becomes combustible at pressures 5 5 psig and lower at 350 F 177 C when mixed with 60 or more volume of air Equipment should never be leak tested with a pressurized mixture of HFC 134A and air HFC 134A can be safely pressured with dry nitrogen The 30 pound cylinders come with the sa
246. efrigerant comes in medium blue containers Compared to R 502 it produces as much as 14 F 9 C lower condenser discharge temperature and better lubricant stability Due to this property it can prolong compressor life It can be used in virtually all R 502 applications AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 411 STEP BY STEP RETROFIT INSTRUCTIONS FOR SUVA HP 62 REFRIGERANT x 1 Remove the existing oil charge from the compressor if Polyol Ester oil 2 10 11 is not already in the system Measure the total volume of oil removed from the system and record it Charge the system with an equal amount of Polyol Ester lubricant Run system for at least seventy two hours Repeat steps 1 2 and 3 twice Remove 502 charge from the unit 10 20 inHg vacuum is needed to remove all of the charge Reinstall compressor if removed Change filter drier with one suitable for use with SUVA HP 62 refrigerant Evacuate system with a vacuum pump vacuum to 29 9 inHg Using normal service practices check the system for leaks Check with the manufacturer of your leak detector for its sensitivity to SUVA HP 62 If any leak s detected seal and re evacuate the system Charge the system with SUVA HP 62 9096 by weight of the original 502 charge Only liquid refrigerant should be removed from the cylinder Run equipment and adjust charge to achieve optimum operating conditions If more charge is needed add in increment of 2
247. eight seconds Install a new compressor a new filter drier and then reconnect the tubing See p 108 A new suction line filter drier will have to be installed on the suction line after a compressor burnout too For residential units charge the unit with about five ounces of the same type of refrigerant used in the system For commercial units charge until the head pressure rises above atmospheric pressure Stop charging turn on the unit and let the unit run for five minutes then purge the system Refer to pp 100 through 110 for procedures for evacuation and charging a sealed system Repeat step 7 two more times Using a vacuum pump evacuate the system and allow the pump to run for thirty minutes See page 117 Recharge the system with the proper refrigerant as indicated on the nameplate of the unit as instructed in the section on charging the system 176 Figure 121 Put some compressor oil on the new gaskets supplied with replacement compressors 2 Gaskets are placed between the compressor housing and the service valves Itis good practice to replace Figure 120 x the existing expansion valve A commercial type Copelametic compressor Note the or capillary tube attached service valve and location of the nameplate The compressor terminals are located inside the box Courtesy of Copeland Emerson Electric Company SIGNS OF A DIRTY CONDENSER Dirty condensers cause a higher evap
248. elay must be replaced Potential relay testers may be obtained from major refrigeration supply dealers if that method is preferred They all come with complete instructions Figure 52a Tabbed TIMER IN DEFROST MODE A lus Power flows through 2 vo aprener contact number 2 paeis a Vr Fresi Seale TIMER IN COOLING MODE Power flows through contact number 4 See figs 8a 8b 8c and 8d Figure 52b 76 TESTING TIMERS IN FROST FREE RESIDENTIAL AND COMMERCIAL REFRIGERATING UNITS In residential units timers are usually located behind the toe plate front grille at the bottom of the unit near the front or back of the unit or sometimes next to the cold control thermostat inside the refrigerator compartment behind the control panel and sometimes in the back of the unit Pay particular attention to figures 11a 11e and 54c 54l Different manufacturers use different timers with different terminals to energize the compressor and the defrost timer This test assumes that terminal 4 is the defrost and terminal 2 is for the compressor Before running a test check the terminals on any particular unit being tested 1 Disconnect the power supply 2 Disconnect the timer 3 Disconnect the block from the defrost timer by pulling it apart Cnntacts seram with ee pr mn LEE d ypical Wirinas igi Figure 53a Courtesy of Paragon Corporation Inc 4
249. em is not working properly here are the steps to follow 386 Figure 212 alvzl Evaporator SS a Tiermistomr ER ee E M lul I Figure 213 TT Bleed Tuba _ p LU Fra poe Receiver Condenser Courtesy of Eaton Corporation Appliance and Specialty Controls Division Make initial electrical check Be sure that the electrical connections to the valve and thermistor are tight and correctly wired If the electrical connections are OK make a simple electrical continuity check of the valve and thermistor using the volt ohmmeter Before you start this check be sure that the thermistor is at room temperature Thermistor ratings are based on 77 F Disconnect the valve and thermistor from the power source Set the volt ohmmeter to the RX1 scale Check the valve by connecting the volt ohmmeter leads to the valve terminals Note the indicated resistance on the ohmmeter Normal resistance of the valve is 70 but it is suitable for operation if the resistance is anywhere within the range of 66 5 to 73 5 Check the thermistor by connecting the volt ohmmeter to the thermistor leads The thermistor is OK if the volt ohmmeter reading is within the tolerance range Defective thermistors generally have higher than normal readings No reading indicates an open circuit AIR CONDITIONING AND REF
250. en too far 2 Inefficient compressor Liquid Line Is Frosted 1 Restriction in filter drier or strainer 2 Valve on liquid receiver plugged or partially closed Hot Liquid Line 1 Expansion valve open too far 2 System low on refrigerant Upper Condenser Coil Cool When Compressor Runs 1 System low on refrigerant ik 2 Inefficient compressor 2 221 Remedy Look for low water supply or flow Check replace valve if necessary Replace valve Readjust valve Replace compressor Replace drier and or strainer Remove restriction or open valve Readjust valve Look for leak and recharge system Look for leak and recharge system Check replace if necessary NOTE If the expansion valve is frosted as unit runs on vacuum check for a clogged strainer or an orifice plugged with ice Remove the restriction or replace valve or wrap valve with hot wet cloth until suction pressure reduces and replace drier 222 A TEST OF KNOWLEDGE ON CONTROLS AND SERVICE VALVES How a particular evaporator temperature by achieved 132 What evaporator temperature is required for a reach in refrigerator p 134 3 How is the high side pressure determined p 135 4 Where is a sight glass installed p 138 5 What is the purpose of a check valve p 144 6 Where is a pressure regulating valve installed p 145 7 8 9 p How does an oil separator work p 154 What is the function of a
251. enser coils By increasing or reducing the pressure in the evaporator an increase or decrease in temperature can be achieved By looking at the chart on page 124 you ll see how each type of refrigerant produces different temperatures under various pressures It is possible to achieve a desired evaporator temperature by manipulating the low side pressure The lower the pressure under a saturated condition holding as much vapor as it can the lower the temperature of the evaporator coil Under a lowered pressure liquid refrigerant in the evaporator coil vaporizes more rapidly and absorbs more heat from the walls of the evaporator coil reducing the temperature of the freezer or the refrigerated area even further In residential refrigeration units this pressure temperature relationship is very often precalculated by the manufacturer When servicing these units check the nameplate to find the type of refrigerant and the required amount of charge That amount of charge automatically produces the correct pressure in the evaporator to bring the coil to its predetermined temperature Charging commercial units is a simple operation By using the temperature pressure chart on page 133 across from the desired evaporator temperature move horizontally to determine the corresponding pressure in the column of the refrigerant type used Hook up the gauges and charge the unit until the compound gauge registers the desired pressures As the unit is ch
252. ept from drying out In some residential units a static type condenser is installed on the back This type of condenser radiates heat to the ambient air without a fan In other units the condenser is located beneath the cabinet also in fig 3 and a fan is needed to force air through its fins for cooling Rear panels Compressor Filter Drier Condenser fan motor Condenser Fan shroud Drip pan Evaporator trim Evaporator 10 Thermostat 11 Grille GUNS REAR MOUNT STATIC CONDENSER Figure 4a Courtesy of Marvel Industries Division of Northland Corporation 16 The temperature inside the fresh food cabinet ranges between 33 F and 42 F while the temperature in the freezer section is between O F and 10 F The thermostat sensing bulb is attached to that part of the evaporator in the fresh food compartment Jof the unit The temperature of the fresh food compartment determines when the unit goes into the defrost cycle A TYPICAL CYCLE DEFROST REFRIGERATOR Air circulation pattern inside a cycle defrost refrigerator Figure 5 Manual defrost systems are not limited to residential units There are some commercial units that operate on the same principle but mostly where temperatures range between 35 50 Bu These convenience centers are used mostly for commercial applications They are a combination of z range refrigerator sink and oven and come in
253. er 2 Remove the red and yellow wires from the wall thermostat and connect them together 3 Reconnect power to air handler If compressor and condenser fan start working replace bad thermostat Otherwise check for a broken wire connecting the contactor coil to the transformer and repair as necessary Nothing wrong with unit Show customer how to properly set thermostat Test power fuse or circuit breaker at the condensing unit See figs 152f and h No power available Power available bad fuse or tripped circuit breaker Power available fuse and breaker OK Check for power at the contactor coil a No power b Power on Contactor hums but doesn t pull Power on and contactor pulls M Check supply power at contactor Check for burnt contacts in the contactor Check for broken wire coming from contactor If only condenser fan runs check for bad compressor or compressor capacitor Replace if necessary Check for a bad condenser fan see pp 82 89 90 91 or a bad condenser fan capacitor if only the compressor runs Replace as necessary Check main circuit breaker or fuse box figs 152f and h Reset flipped breaker or replace blown fuse Reset breaker or replace blown fuse at the condensing unit figs 152f and h Check for low voltage at the contactor coil fig 152d a Voltage OK b Voltage too low Replace contactor coil Call power company to remedy low voltage prob
254. er gallon of water in the machine 7 Allow cleaning solution to circulate for up to ten minutes It may be necessary to recirculate the solution for longer than ten minutes to remove heavier and thicker scale deposits Be sure all distribution and weep holes are clear Drain cleaning solution and flush with water for a minimum of thirty seconds After flushing plug the drain 8 Thoroughly rinse bin with clean water after all components are cleaned 9 Return machine to service discard first batch of ice Remember these directions are for Calgon Vestal Laboratories product nickel safe ice machine cleaner only Other products may have different instructions and precautions Also note the danger label on this and all other products of this nature Since they contain caustic substances that are eye and skin irritants always follow the manufacturer s recommendations for safe handling WATER COOLERS AND FOUNTAINS The framework of a water cooler is usually made of steel and covered with a sheet metal housing Some water coolers provide only chilled water and others produce both chilled and hot water Normally access to the mechanism is provided by removing a side panel Basins in these units are usually made of porcelain coated cast iron or porcelain coated steel to prevent leakage and corrosion The condensing units condenser condenser fan and compressor are located on the bottom of the units while the evaporators are positioned ab
255. erator p 73 Are the contacts in a potential type relay normally open p 73 Explain the checking procedure of a timer motor by direct connection p 77 Why do some capacitors have three terminals p 90 Is the temperature control shown in figure 69 to be used with residential freezers p 95 26 27 28 29 30 Dp mg 10 11 12 13 14 15 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 129 What are the major causes of water leaks inside residential refrigerator cabinets p 125 Is it OK to maintain a five inches clearance on the sides of a refrigerator p 103 What type of compressor motors are used for light commercial applications such as a salad bar pp 61 62 What other terms are used for defrost thermostat p 28 What are the first things to be checked when a unit fails to cool p 127 A TEST OF KNOWLEDGE ON EVACUATING AND CHARGING REFRIGERATION SYSTEMS Name the four methods of charging a unit p 110 When should a suction line filter drier be installed pp 108 109 How is a unit tested for a leak before charging pp 108 109 How can it be made easier to spot the exact point to shut off the charging cylinder valve p 111 When would the frost pattern method of charging a unit be used p 115 What are the possible causes for a refrigeration unit to run all the time without cooling pp 119 120 Can a defective condenser fan motor cause a compressor to sh
256. erature producing elements such as electric resistance heaters flames etc it will decompose producing toxic and irritating compounds such as hydrogen chloride and hydrogen fluoride with pungent odors irritating the nose and throat Do not store HCFC 123 in locations containing alkali or materials such as powdered aluminum beryllium or zinc if there is no air monitor in the room to indicate that HCFC 123 concentration is below 30 ppm AEL in the working space Also as a safety measure be certain to wear proper respiratory protection at the time you are breaking into the sealed system It produces almost the same operating temperatures and pressures in a chiller with a relatively lower capacity compared with R 11 Solid core driers used with R 11 R 12 and R 22 can be used with HCFC 123 refrigerant Lubricants used with R 11 may be used with HCFC 123 For indoor applications use an HCFC specific air monitor 0 to 150 ppm range For more efficiency install air sensors in a location where the average concentration of HCFC 123 vapor is more likely to occur According to ASHRAE American Society of Heating Refrigeration and Air Conditioning Engineers proper respiratory measures should be available for immediate use under circumstances such as a large leak or release AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 413 NOTES ON RECOVERY RECLAIMING and RECYCLING With the exception of a different filter drier and or moisture indi
257. ere is the testing procedure of the defrost system in a Coleman Heat Pump Operate the heat pump in the heating mode for about five minutes voltage Tarminalm gm p Peers SOLID ETATE CIRPUITRS Short across the two SEN JMP posts and the two SPEED UP posts to put unit into defrost fig 176 Maintain the 2 pefrest Period Defrost Initiate H jumper on the test pins until Paata Selection Poste the defrost cycle begins As 1 Dorem Ap roate PELON GR Ses jj LIBET jD SUPE 270 the unit goes into the defrost j tins cycle remove the short from the SPEED UP and SEN JMP posts Allow the unit to terminate the defrost cycle automatically This will occur pum i 14 VAL Tiu CILE T 1 immediately upon removal of the SEN JMP short only if coil temperature is warm enough to signal a complete defrost 2 whenthedefrost control receives thetemperatureterminate signal from the coil thermistor and 3 whentheonboardoverridetimer signals for a timed termination about ten minutes UOISIAIG 510009 UO eIOdIOD uo1e3 jo Ase1ino5 In humid conditions with temperatures near 32 F during normal operation with the heat pump in the heating mode the When installing a heat pump regular air out door coil will gather frost conditioner with the outdoor unit above the causing the temperature of the indoor coil oil trapping is necessary An oil trap coil to drop T
258. erminals This will show the exact capacitance of the capacitor in microfarads Compare the reading shown on the meter with the capacitor rating printed on its side If it is below what it should be the capacitor is weak and it must be replaced Ifthe meter registers no reading it will mean there is a disconnection in the capacitor and it must be replaced TESTING CAPACITORS USING A TEST LIGHT See fig 66 Disconnect power to the unit Discharge the capacitor as in Ib above Check the mfd rating on the capacitor and set the test light selector switch for that range Connect the test leads to the capacitor terminals Turn on the tester The indicator light should glow dimly and go out 92 f If the light stays on it will mean that the capacitor is shorted and it must be replaced g Ifthe light never comes on there is a disconnection in the capacitor and it must be replaced TESTING THERMOSTATS In residential units thermostats are located inside the refrigerator either in the side behind the control panel or at the back Generally the thermostat is behind the cold control knob See Fig 67 TESTING THERMOSTATS USING AN OHMMETER 1 Disconnect the power source 2 Removethe control knob s by pulling it them off 3 Remove the control panel 4 Using a screwdriver or nutdriver remove the screws holding the thermostat Do not damage the thermostat bulb and very gently pull the bulb from where it is seated
259. es the suction or discharge line and leaves the compressor and gauge ports open REVERSING VALVE Reversing valves are used in heat pumps It is a four port solenoid valve with one port connected to the compressor suction tube one port to the discharge tube one to the indoor coil and one port connected to the outside coil See figs 103a and b 104 and 105 Solenoid valves become inoperative due to either electrical or mechanical malfunction If due to an internal short or disconnection a valve becomes incapable of creating enough magnetism to lift the plunger the coil will have to be replaced Remove the screws holding the coil Any disconnection in the coil can be detected when the two coil terminals are touched with the two ohmmeter probes Set scale on RX1 If the valve develops a leaky seat causing the needle to stick or chatter the valve must be replaced Most solenoid valves will not operate unless they are in a vertical position and right side up The voltage rating must be compatible with the replacement valve Figure 102a A CONDENSING UNIT 1 Compressor suction line access valve 2 Liquid receiver access valve high side 3 Pressure control AueduuJo 32 AsazinoD Figure 103 FOUR WAY PILOT DE ENERGIZED CismEprummsur pimchmrgc Tu Compreseco uction FOUR WAY PILOT ENERGIZED COOLING CYCLE Figure 103a tomapnrummii niackarge B A m
260. ese blends may not be sensitive to them I HALOGEN SELECTIVE LEAK DETECTORS A special sensor is attached to these leak detectors to enable the monitor to sense and detect only compounds containing iodine chlorine fluorine and bromine with no interference from any compound other than the targeted one This gives the halogen selective detector an advantage in the number of nuisance false alarms due to the presence of other nontargeted compounds These leak detectors are more sensitive than the nonselective type They are able to detect leaks as little as 0 05 oz per year when used as a leak pinpointer and a 5 ppm detection limit when used as an area monitor They are easy to handle and calibrate AUTOMATIC CHARGING METER Il COMPOUND SPECIFIC LEAK DETECTORS They are the most expensive type of leak detector with the capability of detecting the presence of a single compound without any nuisance alarms FLUORESCENT ADDITIVES It is designed to permit charging or recovery of refrigerant by weight into any air conditioning and refrigeration system or cylinder In addition to electronic leak pinpointers the use of fluorescent additives has been Figure 217 practiced by refrigeration repair personnel Courtesy of TIF Instruments Inc for a long time At the time of servicing the equipment the fluorescents are added to the lubricant in the sealed system When a leak occurs the additive escapes with the refrigerant generally leaving
261. est of these last two readings determines the start terminal In other words number 2 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 59 is the start terminal so the remaining terminal number 3 will have to be the run terminal see fig 39 Some terminal configurations appear as in figure 40 Use the same method to identify these too Figure 37a Different styles of compressor terminals Figure 40 COMPRESSOR TERMINAL IDENTIFICATION OF MAJOR BRANDS Figure 37 Compressor terminals may be identified as in figures 38 and 39 regardless of their arrangement L HERMETIC UNIT TERMINAL COLOR CHART 77 7 7 B Black G Green R Red T Tan W White BRAND NAME STARTING RUNNING COMMON Admiral WwW Airtemp R Carrier Coldspot Copeland Crosley Frigidaire General electrical Gibson Grunow HotPoint Kelvinator Kel Kold Leonard Norge Philco Servel Stewart Warner Tecumseh Universal Cooler Westinghouse Zenith 9 SWDDDDQOBMAHDAHDSSOVSAD 2 579 55 550059055550 Figure 40 60 COMPRESSOR TERMINAL COLOR CODING A QUICK REFERENCE GUIDE FOR TWENTY TWO POPULAR BRANDS Each manufacturer has a color code for the wiring in the circuit The chart above shows the color coding for those wires connected to the compressor terminals This color coding can be used to identify the compressor terminals when the letter marking is not visible For example when checking the compressor in an Admiral
262. esy of Henry Valve Company 10 11 12 13 14 15 16 17 18 19 20 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 397 A TEST OF KNOWLEDGE ON TROUBLESHOOTING REFRIGERANT FLOW CONTROLS What are the possible causes that generally lead to relay burnout pp 354 355 Explain flash gas p 360 How is a flash gas problem remedied p 360 In which direction should the stem on the water regulating valve be turned to increase the flow of water p 391 What regulates voltage to an electric solid state expansion valve p 384 As a general rule what locked rotor amperage reading should be expected on a three ton compressor motor that operates on 240 VAC p 382 In what position should a TEV remote sensing bulb be installed on a seven eighth inch line p 371 How does inadequate subcooling affect the superheat p 363 What are the three possible causes of excessive water flow in a water cooled condenser system p 390 How can a water cooled condenser that is filled with mineral deposits be repaired p 394 Explain how an evaporator pressure regulating valve operates p 362 What scale should be chosen to set an ohmmeter when checking a solid state expansion valve p 386 Why should you not touch both of the terminals of an electric valve with one of the voltmeter leads p 385 When testing an electric valve with a voltmeter what range of reading should you expect at peak loa
263. etermine that the timer motor is not defective I E R 120 4000 about 0 3 A How many components are controlled by the cold control thermostat Four the compressor evaporator fan motor condenser fan motor and the defrost heater Since the resistance of the defrost heater is 25 O what amperage should be expected between the timer terminal 2 and point L I E R 120 25 about 4 8 A 352 faa cee e SCT lt UPLATE POWER SUPPLY PROVIDE DISCONNECT MEANS A 24 VAC thermostat controlled circuit for ML pte cee rb eats a cooling circuit in a single transformer SYSTEM SWITCH MUST BE IN COOL POSITION TO system PREVENT DRAIN ON BARTERSIES A24 VACthermostat controlled circuit using ON COOLING ONLY APPLICATION EQUIPMENT a pilot gas system Mist BEBOWEREDYERNIGROUND A 24 VAC thermostat controlled circuit in CURRENT DRAW FOR Y MUST BE 0 08 OR a single transformer system gas heat with GREATER Y PLUS G MUST BE LESS THAN 1 2 A electric cooling A24 VAC thermostat controlled circuit for a single stage heat pump FE eons ii a DEAR i A POWER SUPPLY PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED _ POWER SUPPLY PROVIDE DISCONNECT MEANS AND i CONNECT VALVE FOR CHANGEOVER ON COOLING OVERLOAD PROTECTION AS REQUIRED OR B FOR CHANGEOVER ON HEATING th CURRENT DRAW FOR W PLUS G MUST BE BETWEEN a PRIMARY CONTROL SUCH AS GAS VALV
264. evaporator coil See p 226 to review the relationship between air temperature and humidity If an undersized air conditioner were used it would have to run longer than normally required possibly continuously possibly it would never bring the temperature to a comfortable level and most assuredly it would increase the energy consumption and raise the utility bill So when the required tonnage is determined find a unit with a rating closest to it Normally a small percentage difference is unavoidable with no adverse result on the effectiveness of the unit This advice applies to units using a heat pump gas fired heaters or electric heating elements too I Fam a E mim Lum panin Fart d ro ie TEFICAL PUMP id i mum mu p Li rrer Fressura When jin pami areri ds bar aw emn prt mi ika fh ma GAUL Lisa za IT am amp iea locamed ack 1 Pe 276 Figure 178b LOAD GUIDE FOR DETERMINING UNIT TONNAGE p 2 gt o o a 2 a Wr qa DIRECTIONS Measure the width and length of the room to be conditioned Find the corresponding length and width on the chart See the minimum and maximum Btu recommended in the area where the lines intersect EXAMPLE For a room with an
265. evaporator plate The power from the timer to the defrost heater flows through a defrost thermostat also referred to as a defrost termination switch which is clipped to the evaporator coil When the ice buildup on the evaporator coil is melted the temperature of the evaporator coil rises to about 50 F 6 F 10 C 3 C The rise in temperature causes the bimetal within the termination switch to open its contacts thus de energizing the defrost electric heating element to end the process of defrosting even with the timer still in its defrost cycle Contacts within defrost thermostats close at 20 F 7 C The whole defrosting process takes between eight and thirty minutes Over 90 of the frost free residential refrigeration units of today are equipped with this type of defrosting system Hot gas automatic defrost system In a hot gas defrost system a bypass line connects the compressor discharge line to the evaporator inlet between the capillary tube and the evaporator inlet see figs 16 and 16a When the unit is taken into the defrost mode a solenoid defrost valve becomes energized allowing discharged hot refrigerant to circulate directly through the evaporator and quickly defrost it It is then drawn back into the compressor through the suction line In this way the condenser and the capillary tube are bypassed In the normal cooling cycle the valve is de energized its defrost port is closed allowing refrigerant to flow throu
266. evelopment of the wiring method in many commercial ice machines and cycle defrost refrigerators The forthcoming pages 315 320 321 and 322 will explain how the manipulation of this series circuit quality has led to the development of the electrical mechanisms of those units parame Figure 179 8 pum cw Mi i Tuba 4 When plugged in this simple series f eh at y So circuit becomes active If the light Taur See bulb or heater burns out the flow of electrons will be completely interrupted and nothing will work because there is only one path for the current to flow AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 293 2 Parallel circuit n this circuit there is more than one path for the current to flow In figure 180 below if current flow were interrupted at point a or point b nothing in the entire circuit would work Current starting at L1 would not be able to reach L2 If power were interrupted at point c only the forward heater and the reversing valve would remain active while the rest of the circuit behind point c would not be energized If the interruption were at point d only the compressor would become de energized while the rest of the system would remain active because the current flow would reach L2 through other branches in the circuit This type of wiring is used for applications in which the whole system is not inte
267. evels Control compressor cycling to match design suction pressures by isolating the automatic electronic low pressure controls Switch off the necessary compressors to maintain the design suction pressures Isolate the defrost control especially on gas defrost systems to maintain discharge receiver pressure and isolate the heat reclaim valve fig 98e to ensure it doesn t operate during superheat adjustments Set TEV superheat Remove the seal cap from the valve to expose the adjusting stem Rotate the stem clockwise to decrease the refrigerant 368 flow through the valve and increase superheat Rotate the stem counterclockwise to increase refrigerant flow and decrease superheat 6 Recheck superheat under low load condition Readjust EPR pressure settings 8 Remove all evaporator condenser false loads and reset all isolated controls N l 15 Oversized Evaporator or Undersized Compressor and High Superheat Resize evaporator or compressor to match load requirements Compare the information on the nameplate with the compressor condenser and valve specifications l 16 Superheat Adjustment Too High Reduce superheat setting CAUSES OF LOW SUPERHEAT Evaporator Outlet 11 1 Overcharge of Refrigerant and or Oil 1 Refrigerant added beyond the proper amount of charge reduces the cooling capacity of the unit causing the evaporator temperature to rise on systems without a receiver An overcharged system is far more likely t
268. evice or uneven evaporator loading External equalizer lines tapped at acommon point although there is more than one expansion valve on the same system Faulty condensing water regulator Restricted external equalizer line Condenser fan cycling based on power switch settings Oversized TEV Evaporator Outlet Remedy Shut off some compressors install hot gas bypass Slow down compressor rpm Check process flows Clamp TEV sensing bulb to free draining suction line Clean suction line thoroughly before clamping bulb in place Install proper size refrigerant distributor Balance evaporator load distribution i e check airflow over entire coil surface Balance the components to load requirements Balance evaporator load distribution by providing adequate air distribution Clean evaporator filters Check reset or replace defrost controls Check control valves for proper setting Clean strainers balance water flow check pump Alter suction piping to increase gas velocity to provide proper oil return or install an oil separator if required Remedy See section 1 14 Clamp remote bulb to free draining suction line Clean suction thoroughly before installing bulb See sec 11 5 Replace faulty distributor must be properly sized If evaporator loading is uneven install proper load distribution fans to balance air evenly over evaporator coil Each valve must have its own separate equalizer line going direc
269. f some liquids are so low that they vaporize far below room temperature In an imaginary experiment if R 134A liquid refrigerant were placed in a tea cup it would immediately vaporize leaving a thick heavy layer of frost on the cup This would happen because the relatively high temperatures in the room would cause the liquid refrigerant with a boiling point of 14 9 F 26 1 C to instantly vaporize The refrigerant absorbs the heat required to boil from the closest object to it the cup When the cup gives up its heat to the liquid R 134A it becomes extremely cold causing the moisture in the surrounding air to condense on the cup surface and form a thick layer of frost THE FOUR ESSENTIALS IN REFRIGERATION 1 Liquid refrigerant tends to vaporize as pressure imposed upon it is reduced It is already known that water boils at a lower temperature at high altitudes where the atmospheric pressure is lower This is what happens to the refrigerant as it is drawn into evaporator coil of a refrigeration unit and the reason the evaporator feels cold 2 Vapor refrigerant tends to return to its liquid state condensate as pressure imposed upon it is increased This is what happens as refrigerant is forced into the condenser of unit 3 Vaporizing refrigerant absorbs heat from its immediate surrounding environment This is what happens in the evaporator 4 When vapor refrigerant gives up a certain amount of heat it changes back to its li
270. f and one after the condenser Those systems are normally assembled on site from components procured independently thus the need for adjusting pressures for system compatibility The only other component requiring specific sizing for compatibility with head pressure controls is the receiver which must be large enough to accommodate the normal operating charge plus the additional charge that would be necessary to totally flood the condenser Installation of a heat exchanger in the liquid and suction line provides for a heat transfer from the warm liquid line to the cool vapor leaving the evaporator causing the following It helps reduce frost on the suction line It reduces the amount of liquid refrigerant in the suction line icd Warm Ligai mafrigaramnk EN Coal Vapor Ged irl It increases the operating efficiency of the HEAT EXCHANGER unit by subcooling the liquid refrigerant It reduces flash gas at the TEV Beltigeren ER ima no Figure 199 Liquid Welrigurast Out FOR UNITS OVER 15 TON CAPACITY Note the location of the pressure regulating valves To control the head pressure in capacity a single valve system as shown in figure 204 can be used units up to fifteen ton M is i a Te Ea m ann mais y n Pe P gin ums Rd m i ATYPICAL DUAL VALVE HEA
271. ff power to the valve and closes off the supply of hot gas if the frost buildup is melted before the timer completes its defrosting cycle If this system is used in an ice machine instead of a defrost timer a thermostat controls the operation of the defrost solenoid The defrost solenoid is energized in the beginning of every harvest cycle Usually the two solenoid contacts are wired to a lamp that becomes energized when the unit is in the defrost cycle The solenoid valve is activated by a timer at a preset time usually midnight or 1 00 AM in commercial units Using this very efficient type of system makes it unnecessary to match hot gas tubing coil for coil with the evaporator AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 189 gure 1007 Flast Chamber dEeservni a Thr im Beppe rechea Uit produci Pade Mrs esters hee Foi cantraBed arate frum Les mitis ibit wale Fr then Posen fle ome anis 11 pare pesi lent tke Free rg chamber whas rhe ager located Laer of ine ane reply Bored iine the Irea chanser arid caer ima Jabra thes mowed imc me bin by the rotation of the auger eed Fans Cage eee Loi p eerie tainlasam Steel Auger hi D ads 1 TNI ue T ila a2 s al LT Pirin Cote nd ier A Wabi Cory 190 When there is a complaint of little or no ice production check the following REASONS FOR THE COMPRESSOR NOT RUNNING 1 Is
272. ffect valve operation If you mount the valve head down use a valve with a bleed tube connection The bleed connection is the third connection on solder type valves It prevents migration of liquid refrigerant to the bimetal chamber On heat pumps always use a valve with a bleed tube Bleed tubes are not available on flare type electric valves Connect the bleed tube downstream of the thermistor in the system suction line see fig 213a On heat pumps connect the bleed tube to the common suction line Remember to use a chill block or wet cloths to protect the valve during soldering When replacing the thermistor simply unscrew the defective one and install the new one Even though the threads are of the dry seal type use a good thread sealer Turn the replacement thermistor tightly into the saddle to guarantee a leakproof seal Figure 213a The threads on the thermistor are the dry seal type However use a good thread sealer like Teflon tape Turn the thermistor tightly into the saddle to guarantee a leakproof seal The 3 32 clearance one or two threads between the thermistor and the saddle top shown in this sketch will properly locate the thermistor which should be flush with the inside of the tube wall If a new location is necessary the suction line adapter saddle should be mounted over a 27 64 0 422 line opening or a Z size drill bit hole 0 412 When a Z size bit is used retap the thermistor with a 1 2 OD to 1
273. fficient time for the oil to return to the compressor crankcase miriramr Deed act Horam inp ami bri A CLEARANCE POS AUR CCA qrym meu Hpt Cw Fig 75 A minimum clearance around a unit Fig 75a Leveling legs under the unit Fig 75b Atwo wheel appliance truck sixteen inch nylon webbing with ratchet and a length of bungee cord used for cargo tie down The programmable electronic charging scale in figure 75c can be used for weighing R 12 R 22 R 500 and R 502 It is designed for refrigerant tanks up to 50 Ibs and has a standard scale up to 80 Ibs When programmed for a particular charge a solenoid stops the charge audible and visual signals show that the procedure is complete TIME 5 TFLAA PTIETTHCS TH HPIAUWIT TLALI Tamad mum sb Bele Ce Tin mia li 2 Electrical power supply should provide enough voltage to start the compressor motor For residential units 115 volts 10 is the 104 allowable fluctuation limit to start the motor In other words the voltage at the wall receptacle must be at least 108 volts Otherwise it will not be able to start the compressor motor A voltmeter is needed to check the voltage Refer to Testing the Supply Voltage and see fig 34 Sufficient ventilation is important where the refrigeration unit is installed In
274. ficiency of the unit by precooling the capillary tube The suction power of the compressor creates a very low pressure environment in the evaporator low enough to vaporize the refrigerant Once the refrigerant reaches the evaporator low pressure environment it 10 is immediately vaporized and heat from its surrounding area is absorbed causing the unit to cool The cooling cycle continues until a preset temperature is sensed by the cold control thermostat causing it to disconnect the electrical circuit to the compressor With the compressor shut off the whole cooling operation stops and the temperature in the refrigerator rises When the temperature in the refrigerated area rises to a predetermined point the contacts within the thermostat will expand and come in contact with one another close causing power to flow to the compressor The unit resumes running and the cooling cycle begins again SUMMARY A compressor circulates the refrigerant through a high pressure and a low pressure coil in one continuous path The evaporator coil the low pressure coil located inside the unit cools the interior The condenser coil the high pressure coil found under or on the back of the unit gives off the heat picked up in the evaporator coil to the surrounding area As it has been explained this transfer of heat would not be possible if the compressor could not create the necessary pressure difference in the system The side of the
275. fig 45 The evaporator in these units is installed in the front and the condenser at the rear outside the conditioned area A fan motor usually capacitor run is installed between the evaporator and the condenser Two long shafts extend from each end of the motor with a fan blade mounted at the end of each shaft The fan blade on the condenser side draws air in through the air vents from the outside forces it through the condenser and then returns it to the outside The blade on the evaporator side draws air in through the evaporator from the air conditioned area and then returns it to the air conditioned area As warm air comes in contact with the cold evaporator coil the moisture in the air condensates on the coil and drips into a pan in the bottom of the unit where the compressor evaporator and condenser sit Most units are equipped with a slinger fan blade on the condenser side As the fan turns it picks up water from the drip pan and slings it through the hot condenser coil to create more efficient cooling See fig 138 Figure 137 Cross section of a window type air conditioning unit showing airflow through the evaporator and the condenser 232 Thus a slinger fan performs two functions 1 it draws air from the outside to cool the condenser coil and 2 picks up the water from the drip pan and throws it through the hot condenser coil which helps with cooling and evaporation of the accumulated water reducing the amoun
276. fire extinguisher before starting this test n9 Locate the noise source by simply putting onthe headphones turning on the amplifier and touching the end of the stainless steel probe to the suspected problem area Disconnect power to the unit Remove the evaporator panel Disconnect the two wires from the termination thermostat and remove it from the unit Set the ohmmeter on the RX1 scale and zero it Then connect the two meter probes to the two thermostat wires with alligator clips Spray the thermostat with CO for about five seconds Be sure the CO does not touch the ohmmeter The ohmmeter should register a zero reading Otherwise replace the termination thermostat Hold the termination switch in your hand for about one and a half minutes or long enough to warm it With the alligator clips holding the probes to the thermostat wires the meter should register an open circuit reading Otherwise replace the thermostat see fig 62 yr 088 Figure 63a A bimetal strip bends with temperature change A Warm B Cold These fixed temperature thermostats are used on refrigerators air conditioners driers and motor temperature controls Different metals have different expansion rates If two metals of different alloys are bonded together and heated they tend to expand toward the metal with the lower expansion rate Conversely as they cool they tend to contract toward the metal with the higher expansi
277. flow into the charging cylinder If the can is left upright only vapor refrigerant can be released Some other refrigerants are quite the opposite they flow out of the cylinder in the form of liquid when the can is in upright position Make it a habitto read the instructions printed on the cylinder first Over load Fratect ur CHARGING BY AMPAETER METHOD ligure This electronic portable charging station has a built in vacuum pump and gauge manifold It greatly simplifies charging any unit as the exact amount of refrigerant charge can be electronically programmed It operates on 115 VAC and is capable of pumping R 12 22 500 or 502 at a rate of 4 ft min from either a 30 or 50 Ib refrigerant tank Manually operated stations have a charging cylinder such as pictured below A unit con Han be changed by oe fee in charging cylinder in force kquid relrperast lio the symem through the high side aone value while the urit ls shest dern A CHARGING CYLINDER Ure ERGO ux Unis annis po AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 113 FERIPNG VALSTS BAETHOIO Pimpa Tye pisari we Tey OF THARAD A TESTEM Ve speiir erg eee erie Br CHARCGINT CYLINDER valen cr service valuen ara connected bo the nach we ao coudre They wid ly cesi eth Tec cer thee iiem depending cn the wem cd dee The wake B senased n
278. formation of ice in the capillary tube temporarily disrupts the flow of refrigerant to the evaporator causing the unit to stop cooling As the evaporator temperature goes up the ice melts causing the circulation of refrigerant to be restored and the evaporator to cool again until the temperature drops low enough to refreeze the circulating moisture in the capillary tube THE MOST COMMON INDICATIONS OF A RESTRICTION Unit runs at warmer than normal temperature with little or no frost on evaporator coil Low side pressure reads partial vacuum High side pressure reads higher than normal Unit runs continuously Higher than normal wattage draw The condenser capillary tube or drier feels cool Low torque compressors used in residential and light commercial applications cycle on overload and take longer than three or four minutes to restart after being shut off This is due to high pressure refrigerant being trapped and separated in the system by the restriction Equalization of high and low side pressures through the capillary tube is difficult to achieve during off cycles 178 A QUICK CHECK FOR A RESTRICTED CAPILLARY TUBE Turn off the system and listen where the capillary tube connects to the evaporator If you don t hear a hissing sound there may be a restriction at that point Apply a warm wet rag to the side of the capillary tube that runs into the evaporator If the restriction is due to an ice formation a hissing sound
279. frigeration Company wish to express their deep appreciation to the following companies for their many excellent contributions of illustrations and information without which the completion of this unique book would not have been possible ALCO Controls Bally Engineered Structures Incorporated Beckman Industrial Corporation Beverage Air Buchbinder Chicago Coari and Associates Coleman Heating and Air Conditioning Copeland Division of Emerson Electric Company DuPont Fluoroproducts Eaton Corporation Controls Division EBCO Manufacturing Company Gates Rubber Company Gibson Henry Valve Company Honeywell Controls Ice O Matic A Welbilt Company Johnson Controls MALCO Products Incorporated Marvel Industries Division of Northland Corporation OMRON Electronics Incorporated Paragon Electric Company Incorporated RAM Freezers and Coolers Manufacturing Incorporated Robinair Division SPX Corporation Tecumseh Product Company TIF Instruments Inc Wagner Products Corporation White Rodgers Division of Emerson Electric Company Wilshire Corporation Schaumburg Illinois vii INTRODUCTION This comprehensive book has been developed to put an average person into the vast commercial and residential refrigeration and air conditioning market within a short period of time It provides all the technical knowledge needed to start a successful refrigeration and air conditioning business anywhere in the world As opposed to th
280. g off power to the unit in case of a energy surge b low voltage c phase loss d phase imbalance e phase reversal or f short cycling It indicates the specific problem s and in which order they occurred Six indicator lights display line status and faults in memory Five seconds to eight minutes adjustable delay timer After power interruption time period starts when power is restored and thermostat closes The two terminals are connected in series with the load 3 This timer will prevent short cycling by delaying the start up of a compressor for five minutes after a power interruption Its terminals are connected in series with the load 4 and 5 Different styles of bayonet type relays for solid state circuit boards They are widely used in ice machines Courtesy of OMRON Electronics Inc Courtesy of Wagner Products Corp Miami Florida 332 Figure 194 High Control Low Praamer untark 19 0 1 Borpmally Ope Centre Balay Contact e x Conder Fan Motnur Wnrmally Opes 1 Closed ns Wall Pherenetat Indoor Fan Balay Call Low Preesure Cunbrnl Cub 0 There Cit imide f A TYPICAL CENTRAL AIR CONDITIONER FOR COOLING LT bc NOTE Section A is the line voltage circuit Section B is the low voltage circuit AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 333 Figure 194b A central air conditioner with the thermostat on Auto position A 230 VAC is
281. g registered on the ammeter dial is too low to be precisely read wrap the wire around the jaw once this will double the reading Divide the reading by two to make it accurate TESTIMG THE DPERATHIB DF THE DEFEDAT HERTER LRG ULAMIP CIN TESTING PROCEDURE 1 Find the schematic wiring diagram of the unit 2 Pinpoint the defrost heater and make a note of its ohm rating shown on the diagram 3 Determine the supply voltage for the unit 4 Divide the supply voltage by the heater ohm rating reflected on the diagram This determines the approximate reading you should expect to get when using the meter 5 Tracethe wire connecting the defrost heater to the defrost timer in fig 72 it is the wire connected to timer terminal number 4 6 Place the jaws of the clamp on ammeter around the wire connected to defrost timer terminal number 4 Turn the timer shaft clockwise and stop when you hear a click You should expect to get a reading of about 5 A 4 8 A as calculated in step number 4 If the meter registers a significantly lower reading such as 1 2 or 1 A you will know that the accumulation of ice on the evaporator plate must be due to a defective defrost system the defrost heater the defrost timer or the defrost thermostat Check them one by one as instructed in the chapter on Testing Residential and Commercial Refrigeration Units to determine the root of the problem CAUTION The foregoing method has a
282. ge will be carried harmlessly to ground instead of flowing through the person who may be touching it at that time Electricity flows through the path of least resistance Since the human body has far more resistance than a grounded circuit stray current flows directly to ground Conversely if someone touches a nongrounded circuit and a short caused electrical charge decides that his her body has the least amount of resistance to its path that person may become the ground NOTE When transporting a refrigerator avoid laying it down because the compressor oil leaves the compressor If it is restarted too soon the compressor will operate without proper lubrication and be destroyed If it must be laid down for any length of time over five minutes it must be placed in its upright position for at least twelve hours before a start up This gives the oil a chance to settle back into the compressor housing GOOD TOOLS ARE HALF THE JOB Good hand tools play a very important role in doing high quality professional work Good service technicians need good hand tools Buy top quality tools and keep them clean and neatly arranged in a good toolbox Some of the best brands available are Proto MAC Stanley and Craftsman Sears The better ones are guaranteed forever against breakage or excessive wear The best tools give pride in ownership make the job easier last longer and consequently become the least expensive So buy the best It is important to
283. gerous concentration of SUVA vapor refrigerant in the air caused by a leak or spill This can be easily detected by installing an air monitor in the area If needed blowers or fans may also be used to prevent dangerous concentrations of SUVA vapor refrigerants in the area Purge and relief vent piping should be routed outdoors far from air intakes If a large leak of SUVA refrigerant occurs it may accumulate in low spots near the floor and occupy the space of available oxygen vital for life causing suffocation Open the windows turn on an exhaust fan s and leave the area AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 401 allowing the vapors to escape Portable fans may also be used to circulate air near the floor Don t return to the room unless an air monitor indicates there is no concentration of vapors in the area or unless self contained breathing apparatus or an airline mask is used Since SUVA refrigerants are virtually odorless and hard to smell a permanently installed air monitor may become necessary for confined areas Inhalation of high concentrations of SUVA refrigerant vapors may cause dizziness loss of coordination and confusion Overexposure to such high concentrations may even cause cardiac irregularities unconsciousness or even death without warning Any person exposed to high concentrations of SUVA refrigerant vapors who experiences any of the above symptoms must immediately move to fresh air and seek medical
284. gh the condenser coil capillary tube evaporator and then back into the compressor suction side Figure 129 shows a different defrost system in which hot vapor refrigerant is circulated through a second coil adjacent to the evaporator 20 Normally a frost free unit is equipped with a fan forced condenser which is mounted at the bottom rear of the unit A fan is mounted next to the condenser and moves ambient air through the condenser to help it dissipate heat NOTE The most common problem in this type of unit is related to a dirty or lint filled condenser A dirty condenser loses its ability to transfer heat causing the unit to run continuously but not cool sufficiently The condenser in a frost free refrigerator or freezer requires annual cleaning In side by side refrigerators the evaporator is mounted at the back of the freezer compartment A damper regulated by the consumer controls flow of cold air from the freezer to the fresh food compartment This cold air forces the warmer air back toward the evaporator cold coil through the bottom of the fresh food compartment See fig 9 In a typical side by side refrigerator the defrost water drain heater can be reached by removing the evaporator panel which is the inside rear panel on the freezer side Figure 9 uosq 5 2 AIR CIRCULATION IN A TYPICAL SIDE BY SIDE REFRIGERATOR Access to the evaporator is gained by removing the inside rear pane
285. gs Both windings are energized during start up When motor gains speed one winding is AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 429 de energized by the starting relay and the motor continues running on the remaining winding split system A refrigerating or air conditioning system in which the evaporator is installed in separate location from the rest of the unit squirrel cage fan A fan with blades parallel to its shaft that moves air perpendicular to its shaft starting relay An electrical device that alternatingly connects and disconnects electric current to the start winding of a compressor motor strainer A filter or screen placed in the sealed system to retain any solid particles that may be circulating with the refrigerant subcooling Lowering the temperature of the refrigerant to compensate for the liquid line pressure losses and to prevent flash gas at the TEV suction line The tube connecting the evaporator and compressor suction side The low pressure side that begins at the inlet of the capillary tube and extends to the inlet of the compressor superheat The temperature difference between the vaporizing refrigerant in the evaporator and the evaporator outlet superheated refrigerant The temperature of vaporized refrigerant surge tank A container installed in the low pressure side of a refrigerating system to prevent short cycling by decreasing the pressure fluctuation in the low side swaging The enla
286. h the coil This type of evaporator cools the refrigerator cabinet or freezer very rapidly Manual defrost refrigerators have a shell type evaporator which is located in the top of the cabinet The shell type is similar to the evaporators used in the cycle defrost type which is a flat plate but bent into a boxlike configuration see fig 15 Frozen food and ice trays are kept inside the shell while the fresh food in the rest of the cabinet is kept at the proper temperature by the cold air emitted from it Shell type evaporators are almost always found in small office type or inexpensive refrigerators Normally as a safety measure an accumulator is installed at the outlet of all evaporators the small cylinder in fig 15 to trap any unvaporized refrigerant It prevents liquid refrigerant from getting into the compressor causing serious damage IN AN ACCUMULATOR LIQUID REFRIGERANT IS TRAPPED IN THE BOTTOM UNTIL IT GETS A CHANCE TO EVAPORATE This can be evidenced by a loud knocking when the compressor runs The liquid refrigerant trapped there will get a chance to vaporize before entering the compressor Capillary tube A length of thin tubing connected to the high pressure side liquid line from its inlet side and to the low pressure side of the system the evaporator from its outlet side Liquid refrigerant is forced to flow through the capillary tube by these two forces Because of the small inside diameter of the capillary tube
287. hange See figure 87 and the pages concerning water cooled condensers for more detail ANSWER In the case of water cooled condensers measure the water temperature as it leaves the condenser through the return pipe by placing a thermometer on that pipe Consider that the ambient temperature and add 20 F to that reading Assume that this exhaust water temperature is 60 F To determine the expected Pogue H7 COM TCEER z 17 a SUM L Woe m 2 Water un 3 Water pump irat mS ee 5 ool a ih b alt Make wp water maple Reuenvoir Anat B Landenaer 10 Evaporator 11 Sigh giuria 12 Fiber diler 13 14 eerie vaha 1 bers woh Gal 18 Tute withic a tube 17 Shell and poil ronde er E Wiener pat b Winer in E Falrigavara in d eigen ool 1A Weber drain lire 19 Leek of thin enermiion resistant material head pressure 60 F 20 F 80 F On the chart 80 F creates 159 9 Ibs in of head pressure in the system when 502 refrigerant is used AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 137 To determine the low side pressure the chart shows that under R 502 22 8 psi produces 10 F REFRIGERANT When dealing with refrigerant always bear in mind that practically every refrigerant has a different boiling point that averages about 59 F below zero Should any refrigerant in its liquid state come in contact with s
288. he defective part must be replaced The capacities of solenoid valves for normal liquid or suction gas refrigerant service are given in tons of refrigeration at some nominal pressure drop and standard conditions Manufacturers catalogs provide extended tables to cover nearly all operating conditions for common refrigerants Follow the manufacturer s sizing recommendations Do not select a valve based on line size Pilot operated valves require a pressure drop to operate and selecting AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 153 an oversize valve will result in the valve failing to open Undersized valves result in excessive pressure drops The solenoid valve selected must have a MOPD maximum operating pressure differential rating equal to or in excess of the maximum possible differential against which the valve must open The MOPD takes into consideration both the inlet and outlet valve pressures If a valve has a 500 psi inlet pressure and a 250 psi outlet pressure and an MOPD rating of 300 psi it will operate since the difference or 500 psi 250 psi is less than the 300 psi MOPD rating If the pressure difference is larger than the MOPD the valve will not open Consideration of the safe working pressure SWP required is also important for proper and safe operation A solenoid valve should not be used for an application when the pressure is higher than the safe working pressure Solenoid valves are designed for a given ty
289. he evaporator size should match the rest of the system If an oversized evaporator is used it will starve and if an undersized evaporator is selected it will become flooded In both cases the temperatures produced in the evaporators will never drop to a desired point RECOMMENDED REFRIGERATOR TEMPERATURES Figure 86 Cabinet Temperature F Back bar or beverage cooler 37 40 Beverage precooler 35 40 Candy case display or storage 59 66 Dairy cases single or double Delicatessen case Dough refrigerator Floral display case Floral storage case Frozen food cabinet closed Frozen food cabinet open Grocery refrigerator Pastry display Reach in refrigerator Restaurant storage cooler Top display case closed Vegetable display open or closed type AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 135 DETERMINING HIGH SIDE PRESSURES The high side pressure is related to the ambient air temperature When servicing a unit with the condenser inside an air conditioned building expect the head pressure to be considerably lower than a unit with its condenser on the roof in the hot summer sun The warmer the surrounding air the higher the head pressure and the more difficult it becomes for the unit to cool As a general rule to determine the expected high side pressure a unit with an air cooled condenser add 30 F to the current ambient surrounding the condenser temperature check the chart on page 133 for the
290. he heat Wet rags and or chill blocks are recommended during brazing They are necessary to keep the valve body cool so that body warpage and close coupled valves will not occur When reassembling do not overtorque 154 OIL SEPARATORS The discharge of refrigerant from the compressor causes some small amount of compressor oil to be circulated with it In heavier commercial units the amount may be great enough to cause damage to the compressor if it runs with insufficient lubrication This oil must be collected and returned to the compressor to maintain proper lubrication An oil separator is installed between the compressor and the condenser The separator screens out and collects the oil and when it reaches a certain level the float mechanism permits the oil to return to the compressor This happens because the pressure in the oil separator is considerably higher than the pressure in the compressor crankcase It is returned to the compressor through the oil return line connected directly to the compressor crankcase see fig 99 Some types of separators are serviceable in which case screens and or elements can be replaced without having to replace the unit It is rarely necessary to add oil to a hermetic compressor Only add oil when there is a refrigerant leak as escaping refrigerant carries some oil with it that will have to be replaced ewm I EVER BS Condenser E Buction bine Fi mai mra Figure 99 x1 meturm
291. he proper refrigerant About 3 oz for residential units and for commercial units just enough to raise the pressure in the tubing above atmospheric pressure Then close the valves start the unit and check the system using a leak detector to ensure there are no more leaks NOTE It is best to check for refrigerant leaks in the low side when the unit is not running as the low side pressure rises during the off cycles 5 Follow the procedures given for evacuating and recharging the system 6 Sandpaper all the new silver brazed joint to ensure no flux residue is left in the tubing Flux contains acid and corrodes copper if left on the tubing Then vacuum the system to force out the moisture that penetrates the AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 125 system during the repair and recharge the unit with the proper amount of refrigerant AIR LEAKS IN THE CABINET WALLS AND DOORS Residential units with freezers cause trouble when there is a puncture in the inside or outside wall of the unit through which air penetrates the walls This becomes apparent when the owner notices a swelling in the side or back of the unit What happens is that air with moisture in it penetrates inside through the puncture and condenses the inside surface of the cold walls of the unit and develops a gradual ice buildup To remedy this problem unplug the unit and place a very low output heater inside the cabinet with the door closed This ca
292. he rising 26 evaporator temperature the gas expands and exerts more pressure on the bellows As a result the contacts are forced to close by the expanded bellows restoring the flow of current to the compressor motor On some freezer and refrigerator models the sensing bulb is not attached to the evaporator in which case thetemperature of the refrigerated air is transmitted to the operating mechanism Starting relay Because starting a compressor requires more torque and draws at least three times the amperage of its normal running Current type speed compressor motors are equipped with Push on style starting relay a starting winding and a running winding and ai i i i C S both compose the stator At the instant of starting current flows through both windings When motor speed increases to about 7596 of its normal running speed a starting relay disconnects power to the starting winding and the running winding continues operating the motor see fig 13 Since heavy wire is used in the starting winding if it runs more than a few seconds it will overheat and possibly burn A starting relay is an electrical device that energizes the starting winding for a brief time The starting relay plays an important role in the life of a compressor motor Should the relay not disengage from energizing the starting winding the starting winding in the compressor motor will burn and the compressor will have to be re
293. he tower to circulate next to the condenser coil then returned to the tower by a water pump Water evaporates at the rate of about two gallons per hour for each ton of refrigeration This water loss is replaced from a reservoir or a water inlet pipe by a float mechanism inside the cooling tower The water return inlet in the tower must stay under water at all times to prevent air from entering the cooling system If air gets into the system a great deal of heat transference will be lost and the efficiency of the unit will be reduced When this happens the air pocket can be forced out of the system by opening the water supply valve and letting the pressure drive it out Be sure all the air bubbles are forced out before turning off the water valve Normally there is a coarse screen on the inlet side of the pump to screen out large particles of foreign matter from the city water Also several chemicals are available to prevent algae slime fungus and rust from forming in the cooling tower There are three types of water cooled condensers 1 shell and a tube 2 a tube within a tube 3 a shell and coil 1 Inthe shell and tube type water cooled condenser see illustration on page 187 water flows through several straight tubes inside a shell that contains the hot refrigerant The shell also acts as a receiver for the refrigerant 2 In the tube within a tube type condenser see fig 87 the inner tube carries the cooling water flowing
294. he valve stem counterclockwise to decrease the superheat increasing the refrigerant flow to the evaporator Turn the valve stem clockwise to increase the superheat decreasing the flow of refrigerant to the evaporator 162 BULB LOCATION ES Bell Cerrect Incorrect Figure 110d Never place a bulb in a trap or pocket in suction line Liquid and oil in thetrap will affect bulb temperature reducing valve efficiency us Bulb on a small Bt Bulb large suction line Figure 110e On suction lines 7 8 OD and larger install the bulb at about a four o clock position on the suction line Figure 110f 6 Badrigarant Lr vapur Bafrigerant Limit Badriuwmam REFRIGERANT PHYSICAL CHANGES IN THE EVAPORATOR COIL At A hot high pressure liquid refrigerant enters the TEV At B cold low pressure liquid plus flash gas enters the evaporator At C all of the liquid refrigerant is boiled off or vaporized by the heat load latent heat Between C and D the vapor temperature increases dramatically as further heat load is applied sensible heat At this point the gas is superheated above its saturation temperature At D suction line temperature of the superheated gas is monitored by the sensing bulb which signals the TEV to open or close accordingly Good TEV performance depends on the accurate adjustment of the superheat so accurat
295. he walls in the back or even in one or more of the shelves AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 23 REFRIGERATION UNIT COMPONENTS Automatic defrost timer It is a device used in automatic defrost Figure 11a refrigerators and freezers to take the system into the defrost and then back to the cooling mode in regular intervals It consists of an electric motor and a switching mechanism see fig 11a The electric motor is geared to move a cam in such a way that after every six eight or twelve hours of compressor operation depending on the design of the timer the cam rotates from 1 As the timer motor operates the One contact to another for no eccentric cam switches from one longer than thirty minutes This causes temporary change the direction of current flow from the cooling terminal to the Figure 11b defrosting terminal and then back to the cooling terminal again The cooling terminal of the timer is wired to the compressor and the evaporator fan motor circuits The defrost terminal is wired to the defrost heater or a defrost solenoid valve circuit See figs 54C through 54L for more detail Frost View A residential timer When the timer takes the system into the defrost cycle the compressor and fan motors remain de energized and the defrost heater becomes energized When it takes the system into the cooling mode the compressor and evaporator fan motors
296. hen touched For optimum efficiency the condenser should be cleaned every year OUTLET LIMES There are two types of condensers commonly employed in residential units static and fan forced convection The static type is mounted on the back of the freezers and refrigerators It radiates heat through natural convection without the use of a fan As air in contact with the condenser tubing or fins absorbs heat from the hot refrigerant and becomes heated it expands and rises and cooler air occupies its space see fig 4a The fan forced type is mounted beneath the unit When the compressor operates a fan moves air through the condenser tubing fins see fig 3 Linted condensers should be cleaned regularly to prevent any restriction of air circulation When air 30 circulation is blocked by a linted condenser heat cannot be removed from the vapor refrigerant fast enough to bring it back into its liquid state as it leaves the condenser Consequently the evaporator will no longer cool the unit runs continually the temperature never drops to a point low enough to satisfy the cold control and the high side pressure rises higher than normal causing the compressor to burn out Be sure that enough clearance is always provided for proper air circulation Evaporator When liquid refrigerant reaches the evaporator it vaporizes or boils and absorbs heat from the freezer Sometimes the evaporator is referred to as a cooling coil Due to the co
297. his in turn causes should be provided for each twenty feet of rise Be sure to seal the holes in the structure made the defrost timer to be activated in for the condensate drain and refrigerant lines response to the control thermistor located in the condensing unit Suiuonipuoj ury pue Ase1no5 There are three different methods of connecting a solid state defrost timer board to a heat pump system Figure 175 B is a White Rodgers defrost board that can be used as a replacement part for most air conditioners As shown in figure 175 F all the terminals on the board are marked Figure 175 C shows how to wire the board to the 24 volt line when only the defrost relay is to be connected to the board terminals Figure 175 D shows how to wire the defrost board to the 24 volt system In this method a sensor a thermistor and a defrost relay are connected to the board terminals Figure 175 E shows the method by which the board terminals are connected to the wall thermostat and the defrost relay When an electric valve is used in a heat pump only one valve is installed between the indoor and outdoor coils It maintains in whichever coil is serving as the evaporator Courtesy of Coleman Heating and Air Conditioning AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 271 A bleed tube should be installed between the valve and the suction line to prevent liquid migration and chilling the bimetal chamber with
298. his moisture drips on the floor If water is found on the floor inspect the heat exchanger More than likely the insulation is damaged or unwrapped Put these two lines together and bind them with an insulation such as duct tape and the condensation will stop In commercial refrigeration and air conditioning units the suction line is covered with a heavy sleeve for insulation to prevent condensation AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 127 REFRIGERATION SYSTEM DIAGNOSTIC CHART For Residential Refrigerators and Freezers 1 Defective components 2 a Pinch off suction tube as in 1 keep the unit close to compressor about from cooling Operates 10 b Install piercing valve between pinched off point and compressor and connect gauge c Run the 1 unit for 2 minutes If in that time the compound gauge needle drops below PSI compressor is O K otherwise replace the compressor 3 For best results when running aleak test check the high side while the unit runs leak test check the high side while the unit runs Check the low side while the unit is turned off Cabinet Warm Compressor Check for a non sealed system problem suchas linted condenser defective condenser or evaporator fan door gasket defrost system airflow baffle out of adjustment or cabinet light stays on Did not find 4 0 Ib in is a general specification Non sealed system non sealed system for
299. his type a bulb attached to the thermostat is fastened to the evaporator coil The bulb is filled with refrigerant As the bulb senses temperature changes the refrigerant in it expands or contracts and transmits these changes through the line to the thermostat which in turn causes the bellows to flex and open or close the contacts in the mechanism The thermostat may be located anywhere as long as the bulb touches the evaporator coil and the line is not exposed to extremes of temperature to prevent transmission of erroneous readings to the thermostat Be sure that the sensing bulb bracket is positioned in a way that the bulb makes full contact with the evaporator coil and the nuts and bolts are securely fastened When coiling or uncoiling the line on bulb type thermostats care must be exercised to prevent kinking or breaking it to preclude refrigerant from escaping or becoming trapped in the line This will render the thermostat useless E a 5 E E B E A BULB TYRE TEMPERATURE Figure 68b t CONTROL USER IN COMMERCIAL Courtesy ed Joran Contra LIMITS Figure 68 A Used on water beer and beverage coolers and vegetable and meat display cases B Bulb type temperature control for applications with temperature range between 40 F and 90 F C Industrial type range to 150 F D Sensing bulb bracket Figure 68d AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY
300. hrough a path that offers some resistance to the flow of electrons heat is created When a unitis activated every component in the electrical circuit is affected by these two characteristics and perform different functions establishing the mechanism of refrigeration and air conditioning The creation of a magnetic field causes the starting relay of a compressor motor to operate or a solenoid to open or close a valve The creation of heat causes thermostats to open or close a circuit a thermister to increase decrease or stop the flow of current passing through it when used in the control of temperature etc Thus the creation and utilization of heat and magnetism in the different components in the electrical circuit establish the electrical mechanism of the unit Courtesy of Beckman Industrial Corporation AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 305 REMOTE MOUNTED EXPANSION BULB THERMOSTAT FOUR DIGIT MULTIMETER COMPRESSOR TEST CORD Verifies the status of NO and NC contacts of coils contactors and thermostat contacts Checks power to coils and contactors CLAMP ON MULTIMETER CONTROL CHECKER Courtesy of Wagner Products Corporation Courtesy of Robinair Division SPX Corporation Miami Florida 306 SCHEMATIC WIRING DIAGRAM SYMBOLS Iron core transformer Transformer Circuit breaker Overload protector Three phase motor Fusible link Overload protector Overload protector
301. hut off and nothing else in the other circuits will be affected since current is able to complete its path through the E G H F circuits This is because all the series circuits are wired in parallel Single praspar Above The lamps the heater baje xm and the fan are all wired in a parallel circuit Below and right The schematic wiring diagram below is the same as the series parallel pictorial diagram in figure 181 A Series Parallel Circuit Figure 181 a limis Speed Heatzsr Every electrical circuit is affected by the three elements of voltage amperage and resistance There is a relationship between the resistance voltage and amperage which is shown by the equation E IxR Where E is electromotive force EMF voltage l is the intensity of an electrical current amperage and Ris the resistance in a circuit This is known as Ohm s law AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 295 By using this equation one unknown factor can be determined if the other two are known Graphically it looks like this If the amperage and the amount of resistance in a circuit are known 2 to find the voltage put a finger over This will determine that the amperage 1 must be multiplied by the resistance To determine the resistance put a finger over R divide the voltage by the amperage
302. ial unit using R 22 at an ambient temperature of 90 F pp 133 and 135 What is the recommended refrigerator temperature for a floral display case p 134 What temperature does R 12 produce at 30 psi p 133 What temperature does R 22 produce at 61 5 psi in an evaporator p 133 What does the oil pressure safety control do when the low side pressure goes higher than the oil pressure in the compressor p 144 Does the solid state thermostatic expansion valve operate by pressure in the evaporator p 165 What are the possible causes for the refrigeration unit to run too long pp 219 220 What are the possible causes for a start capacitor to burn out pp 219 220 What are the possible causes when a compressor hums but does not start p 219 What are the three rules of thumb for superheat adjustment in different units p 161 When the tubing is kinked what symptoms manifest themselves in the unit p 208 REPAIR TECHNIQUES IN COMMERCIAL AND RESIDENTIAL AIR CONDITIONING UNITS This section covers step by step procedures in troubleshooting and repair techniques for commercial and residential central air conditioners wall and window units heat pumps rooftop console air conditioners and split systems Courtesy of Coleman Heating and Air Conditioning 226 Since air has weight it takes energy to move it and it is capable of transferring heat As the temperature of air rises it expands and occupies more space
303. ical circuit symbols are used in schematic wiring diagrams Schematics are simpler and easier to read than the pictorial wiring diagrams They are used on large and complex circuits Since these symbols are internationally recognized they make it easy for any service technician to read the schematic wiring diagrams Sometimes some variations of a certain symbol for the same component can be noticed These are very limited and should not create any problem Bear in mind that in order to energize an electrical circuit and make it become operational current flowing into the circuit from one side of the receptacle must be able to return to the other side of the receptacle Should any interruption such as a broken wire loose connection or a defective switch in any part of the circuit prevent the current from returning to the other side of the receptacle the circuit becomes inactive and no component in it will work In a 110 130 VAC circuit the hot side of a receptacle is referred to as L1 and the neutral side L2 In a 220 250 VAC circuit L1 and L2 sides of the receptacle are both hot In a three phase circuit L1 L2 and L3 are all hot terminals These symbols are used in wiring diagrams for quick circuit identification In any refrigeration unit all of the components function as they do because of the conversion of electrical energy into heat or magnetism When current flows through a coil of wire it creates a magnetic field When it flows t
304. ien a4 ty inten ad Aupechaat TT hii iter Di bili Ld pala ed ee Lili 164 Figures 110d and 110e show the ideal placement horizontal of the bulb in relation to suction line size Never put the bulb at 6 o clock because it may sense the temperature of the oil flowing through the pipe rather than the temperature of the refrigerant And be sure the bulb location is on a free draining suction line A good way to check a suspected punctured sensing bulb is to close one hand around the bulb and its connecting line The heat transferred to it should cause the refrigerant in it to expand and open the valve Otherwise the valve has to be replaced as the refrigerant in the bulb must have leaked out DIAGNOSING THERMOSTATIC EXPANSION VALVES A STARVED EVAPORATOR WITH AN UNEVEN FROST PATTERN 1 5 resulting in poor cabinet refrigeration may be due to ther following e Est 1 1 Loss of refrigerant from the thermal bulb if undependable erratic refrigeration is evidenced 2 Valve needle stuck shut This very seldom happens The evaporator no longer cools 3 Clogged expansion valve screen Evaporator loses its cooling ability 4 Moisture in the system The evaporator cools sometimes and sometimes does not 5 Under capacity valve installed Evaporator temperature never drops to the desired point 6 Inside of valve covered with wax Poor or no ref
305. igh side float system or systems using an expansion valve s Systems with capillary tubes use an accumulator which is installed at the outlet of the evaporator The motor control temperature sensing element is installed on the coil just before the accumulator on the suction line Figure 118 Aueduio 911399 puejadog AsayinoD A condensing unit typical of those used in commercial walk in coolers or freezers open or closed display cases salad bars beverage coolers ice machines large water coolers ice cream and frozen yogurt machines and food preparation bars These are placed inside self contained units or in back of the building or on the roof for split units A pressure control not shown is normally located on the unit 1 Compressor 2 Start Capacitor 3 Control Box where the starting relay and line wire connections are located 4 Receiver 5 High side Access Valve 6 Low side Access Valve 7 Condenser Coil 8 Condenser Fan 9 Compressor Terminal Cover 10 Compressor Nameplate 11 the nameplate for the condensing unit CAUSES OF COMPRESSOR SHORT CYCLING Short cycling means that a refrigeration unit starts and stops much more frequently than it should The most common causes of compressor short cycling are 1 a weak overload protector 2 low line voltage 3 a dirty or linted condenser 4 a defective condenser fan 5 a bad pressure control in commercial units
306. in one direction and in the outer tube the hot refrigerant flows in the opposite direction Water velocity should be about seven to ten feet per second If it is faster than that it can remove the oxide coating and cause pitting If it is circulated slower than three or four feet per second it may cause scaling The groove in the tube increases surface area and consequently provides a higher cooling efficiency AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 213 3 Inthe shell and coil type condenser see fig 87 a coil of tubing is placed inside the condenser shell In this arrangement the cooling water flows through a coil rather than several straight tubes Sometimes the condenser is placed directly inside the cooling tower and the air cooled water runs right over it Continuous circulation of water is provided by a water pump installed in the piping In smaller systems city water is circulated through a tank that contains the condenser coil Water flow through this tank is controlled by a pressure actuated water circulation control valve which has a tube connected to the compressor discharge line When the head pressure goes A SHELL AND TUBE TALE FOR up the pressure exerted from 3 Feri Ligu f the discharge line to a diaphragm FLOAW OF REFRIESERANT LEVEL within the water valve causes the WATER D REFEILEHANT IH valve to open further and let more WATER GUT co
307. in the valve See figs 177 and 177a The electric valve on heat pumps can be controlled by two methods 1 A thermistor is installed in the common suction line between the reversing valve and the compressor See fig 177 2 Two thermistors wired in series with the electric valve are installed at the outlet of each coil See fig 177a The valve is controlled by either one of the thermistors In the cooling mode thermistor number 1 controls the electric valve and thermistor number 2 has no effect on valve operation because it senses high temperature gas and is self heated to a negligible resistance In the heating mode thermistor number 2 controls the valve and thermistor number 1 is self heated to a negligible resistance No check valves are required when electric valves are used xx Figure 177 Hinimum E Clearances Line Thermimkcr I ThaermisLor UOISIAIG 51030079 U6H6300105 UO JO so11no3 1B min 4 SELECTING THE BEST HEAT PUMP LOCATION Before installing a heat pump or regular air conditioner locate the outside unit as near as possible to the indoor coil to prevent lengthy runs of refrigerant lines Locate the outside unit so it will not discharge air under eaves or gutters and as far as practical from the clothes dryer vent Rain or melted snow should not run off onto the outdoor unit Aminimum clearance of eighteen inches is required for service at the contro
308. inals are shown as L1 and L2 and the three hotterminals in a three phase receptacle are shown as L1 L2 and L3 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 301 A voltmeter is widely used in diagnosing any interruption in an electrical circuit It registers a voltage reading only when there is a potential difference between the locations where its probes touch Potential difference in an electrical circuit is created across any point of disconnection such as a burnt fuse an open or defective switch a broken wire etc When the two probes touch across an open switch the meter registers a voltage reading but when the switch is closed the meter registers volt reading A voltmeter always registers a voltage reading when its two probes touch across the terminals of a load whether or not the load is functional When the two voltmeter probes touch the two terminals of a fuse a voltage reading will mean that the fuse has burnt out an interruption in the circuit If the meter reads 0 volts it will mean there is no disconnection between the two fuse terminals Therefore one can conclude that the fuse is good o PROBLEM 1 In the bottom illustration the power is on and there is no heat from the heater Placingthe probes across the heater C D a O volt reading is registered This will mean power does not reach the heater because if it did the meter would register a reading even if the heater were defective You should a
309. ing relay is to test other components in the circuit first such as overload AGA W RING METER protector the capacitor thermostat FOR A COMPRESSOR MOTOR USING A SOLID STATE RELAY or pressure control if used in the system If everything else checks out j E Solid State Helay Figure 52 good then replace the relay However ifa more sophisticated method is preferred use an electronic relay tester They are relatively inexpensive and are sold by many supply houses NOTE Relays are interchangeable provided that one with the same A TYPICAL WIRING METHOD As FOR A COMPRESSOR MOTOR rating is used USING A HOT WIRE RELAY A quicker way of checking the relay that experienced technicians use today is outlined below METHODS FOR TESTING ALL TYPES OF RELAYS First prepare a special test cord This should be at least twelve gauge wire with insulated alligator clips at each end and a momentary contact switch normally open in the center Total overall length should be about a foot l TESTING A SOLID STATE THERMAL HOT WIRE OR CURRENT MAGNETIC TYPE RELAY These relays are directly or indirectly attached to the compressor run and start terminals The relay terminal attached to the compressor run terminal is marked R or sometimes M for motor The relay terminal which is attached to the compressor start terminal is marked S See figs 50 and 51 This test is conducted by bypassing the relays
310. ins Make certain vacuum pump discharge lines are free of restrictions Any restriction may cause the formation of a combustible mixture due to the discharge pressure increase x sure filled cylinders are regularly checked for air content AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 409 CHARGING A SYSTEM WITH SUVA HP 80 OR HP 81 SUVA HP 80 and HP 81 replace R 502 in the existing systems equipped with expansion valve s or capillary tube s such as food service and warehousing refrigerated transport units freezers and display cases used in supermarkets walk in freezers etc Systems using HP 80 or 81 should be charged with alkylbenzine or Polyol Ester lubricant Furthermore filter driers used in existing systems must be replaced with ones compatible with the new generation refrigerant blends Systems equipped with reciprocating screw scroll or rotary compressors can be cost effectively retrofitted with HP 80 or HP 81 SUVA HP 80 offers a slightly higher capacity as compared with R 502 It is suitable for use in frozen food and dairy display cases ice cream dispensers walk in coolers freezers beverage and vending machines Due to the difference in liquid density of R 502 and HP 80 or 81 the system will require less weight of the HP 80 or 81 than the R 502 The amount of charge will vary according to the size of the evaporator condenser length of tubing runs and the size of the receiver if so equipped General
311. ion line access valve and get a pressure or vacuum reading Attach a thermometer close to the suction line access valve and insulate it to get an accurate reading Use another thermometer to determine the ambient air temperature entering the condensing unit On the chart figure 178c find the air temperature entering the condenser and move horizontally until you intersect the curve indicating the suction line pressure registered in step 2 Then move downward from that point on the curve to determine the corresponding suction line temperature If the suction line temperature reads higher than the indicated figure on the chart add refrigerant until the temperature falls within the parameters of the chart Bleed some refrigerant off if the suction line has a temperature lower than that shown on the chart If you are using the weight method of charging the amount of charge is sometimes printed on the nameplate the system must be thoroughly evacuated Weigh the refrigerant tank carefully and subtract the amount of charge from the total weight of the refrigerant tank Leave the tank on the scale and charge the unit until the scale indicates that the proper amount of refrigerant is added to the system For more accuracy in charging a system by weight a Dial A Charge cylinder can be purchased from refrigeration supply firms Of course if the unit is equipped with a sight glass charge the unit until the bubbles in the sight gla
312. is a leak in the system Repair leak change filter drier and recharge If pressures are normal the pressure control needs to be replaced Check starting voltage drop in receptacle as previously instructed against required voltage on nameplate Also check for undersized or a too long extension cord and replace it Observe safety rules and bypass the thermostat terminals If compressor starts thermostat is bad and must be replace Observing safety rules check and replace relay if necessary Following the safety instructions check and replace capacitor if necessary Observing safety precautions check and replace the overload protector if necessary Check all wiring and connections and repair as necessary Test compressor and replace if necessary Water Does Not Come Out Cool while Unit Short Cycles 1 Faulty overload protector 2 Faulty starting capacitor 1 Check or replace if necessary 2 Check or replace if necessary 206 Problem and Possible Cause Remedy 3 Faulty starting relay 3 a Unplug unit and allow compressor to This test has a potential shock hazard Be sure to take all safety precautions before and during the procedure Linted condenser Faulty condenser fan or stuck or restricted fan blade Loose connections Shorted or burned out compressor Water Does Not Come Out with Enough Pressure Low water pressure in building Water push button valve defective Inlet water valve fa
313. isters voltage below the requirement of the contactor coil tell the customer to call the local power company to remedy the low power input to the property The voltage produced by the secondary winding is directly proportional to the input voltage to the primary winding of the transformer If the primary voltage is too low the secondary voltage will be too low Determine the required voltage that energizes the contactor per instructions beginning on page 218 or by checking the back of the contactor If the contactor pulls but the unit will not start the problem can be due to an interruption in the compressor and condenser fan power supply line 246 A QUICK WAY TO CHECK FOR A BAD FUSE OR CIRCUIT BREAKER 1 Turn the unit on and use your digital multimeter on the volt setting fig 152f 2 Touch the two probes on 1 and 2 and 3 and 4 If you get a voltage reading on either one of them replace the blown fuse A good fuse should read zero on the voltmeter 3 Touch 5 and 6 the meter should register a reading of 220 240 VAC And touch 6 and 7 or 5 and 7 you should get a 110 130 VAC reading Otherwise call a licensed electrician to remedy the problem Sometimes the main circuit breaker trips causing the disruption of power to the unit Find the circuit breaker box and return the tripped switch to the on position Pay particular attention to all safety precautions while working with contactors TESTING A CONTACTOR WITH AN OHMMETE
314. it such as replacing a compressor or a filter drier repairing a puncture in the tubing replacing a capillary tube etc When the repair is done take these three steps prior to charging and operating the unit 1 Remove the old filter drier and install a new one 2 Evacuate the air from the system by using a vacuum pump or by the purging method where the compressor is used as the pump 3 Make certain there is no refrigerant leak in the system by running a leak detector over the lines and components and also by checking for a pressure rise in the system after evacuation REPLACEMENT OF A FILTER DRIER 1 Remove the old filter drier If it is silver brazed use a tubing cutter and cut about one fourth inch from the drier If it is a flared connection unscrew the nuts Do not use the same flare again as it can become weak from tightening and loosening the nut Cut the old flared end off and make a new one Install the new drier paying heed to the flow direction arrow on the body of the new drier When using a flared connection wrap the male threads of the connector on each end of the drier with Teflon tape to get a good leakproof seal Residential units do not use flared connections because of their smaller size of tubing on which brazing works easily Some of the driers used in residential units also come with access valves see figs 76e and 76f Commercial filter driers are sized according to the tonnage of the unit Before buyi
315. it but the compressor fails to start what electrical components are to be checked The capacitor thermostat switch and compressor How is the compressor checked By direct testing Connect the L1 and L2 of the 220 VAC to the compressor common terminal and the capacitor terminal for the run winding bypassing the switch Make sure the capacitor is not defective Observe all safety precautions How is the fan motor tested Bypass the selector switch and the compressor a Disconnect the unit from the power supply b Disconnect m n and p wires from the switch and the compressor run capacitor c With a jumper cable connect L1 and L2 directly to wires n and p with the m wire well insulated When power is reconnected fan should start d Disconnect L1 and L2 from power e Connect L1 and L2 to wires m and p with n well insulated f Connect power to L1 and L2 The fan motor should start with either of these methods if not it is defective Make sure the fan capacitor is not defective WARNING THE ABOVE TWO PROCEDURES HAVE A POTENTIAL ELECTRICAL SHOCK HAZARD BE SURE TO USE COMMON SENSE AND OBSERVE ALL SAFETY PRECAUTIONS 350 USE THIS WIRING DIAGRAM TO INSTALL A CENTRAL AIR CONDITIONING UNIT Usually the transsormar i amp installed in Ihe air hendar or furnace on fig 163 Tranaformer A TYPICAL COMMERCIAL OR DOMESTIC CENTRAL AIR CONDITIONING SYSTEM or 24D VALL Haating amp Cool leg 2 24 vr
316. it from the unit See step b in Testing Capacitors Using an Ohmmeter 3 Puta 60 light bulb in socket A fig 34a 4 Insulate the alligator clip marked S and connect the alligator clips marked C and R to the two capacitor poles 5 Connect plug B to power The lamp will a glow dimly if the capacitor is good b not glow if the capacitor is open replace the capacitor c glow brightly if the capacitor is shorted replace the capacitor 6 Ifthe capacitor checks good replace the 60 watt bulb with a 200 watt bulb and leave the capacitor as it is for no longer than five seconds 7 Disconnectthe cord from the power Using a heavy insulated wire short across the two capacitor terminals A spark is the indication of a good capacitor meaning that the capacitor can load and discharge Bigger compressor motors that require more starting or running torque due to heavier loads use capacitors to increase their torque This is especially true in commercial refrigeration and air conditioning They are referred to as start or run capacitors Some compressors use only run capacitors and some use both Capacitor testers can be purchased at refrigeration supply houses for very affordable prices 56 Faure Ha A TEST Su Gn cindy ieee with the rreitrriaks 1f host pl LI aada wire Tat lamp wickrizr fures fe 1 ga wit aee maly open 15 reer
317. its lowest setting and the following is observed a The compressor operates for about three minutes and shuts off for about four minutes The inside fan motor is operating c The outside fan motors 1 and 2 are not operating Name a specific component that could cause this problem The CR1 contacts responsible for energizing OFC1 and OFC2 have burnt out On a service call for insufficient cooling the wall thermostat is set on COOL and AUTO and it is on its lowest setting During the operation of the unit it is observed that a the is operating b OFM2is not operating c is operating What three components could cause OFM2 to become nonoperational Either a defective FCPS switch or OFM2 has shorted out or one of the FU2 fuses has blown 340 10 11 12 13 14 15 16 17 18 On a hot summer day a service call for insufficient cooling has produced the following with the thermostat set on COOL AUTO and its lowest temperature a The compressor is operating The IFM is operating c OFM1 and OFM2 are both operating and some cooled air is delivered List the electrical components that are likely to cause insufficient cooling Explanation LLS the liquid line solenoid is responsible for opening the liquid line to allow more refrigerant to circulate in the system as the ambient temperature increases in the conditioned area This is activated by the TC2 switch in the wall thermostat An
318. its resistance and increases current input to the valve heater The valve opens more Figure 208 Figure 209 i4 volts ZERO VOLTAGE VOLTAGE APPLIED VALVE CLOSED VALVE OPEN Courtesy of Eaton Corporation Appliance and Specialty Controls Division AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 385 This continues until enough liquid refrigerant is fed into the evaporator to reduce superheat Figure 210 THERMISTOR SELF HEATS VALVE OPENS Figure 211 THERMISTOR COOLS VALVE BEGINS TO CLOSE Courtesy of Eaton Corporation Appliance and Specialty Controls Division The wet refrigerant gas cools the thermistor increasing its resistance Less voltage is sent to the valve heater and the valve moves toward closing Troubleshooting and servicing thermal electric valves is relatively easy All you need is a standard volt ohmmeter a service gauge manifold and a few minutes of your time By using the volt ohmmeter and normal service procedures you can quickly identify system conditions and check valve operation Be sure to observe these precautions 1 Never put more than the output of a 24 volt transformer into the valve circuit 2 Do not put 24 volt current directly to the thermistor unless the valve is also wired into the circuit 3 Do not touch both terminals of the valve with one of the volt ohmmeter leads You will short out the valve and damage the thermistor If you determine that the syst
319. ive the head pressure high side pressure goes up because the condenser is no longer able to dissipate heat from the refrigerant into the surrounding air The unit loses its cooling capacity and runs continuously as the temperature control never becomes satisfied The compressor overheats to the point where the overload protector sensing the abnormal heat shuts it down until it cools enough to allow a restart A dirty condenser is a common cause of compressor short cycling cycling on overload SHORT CYCLING AND A BAD START CAPACITOR Astart capacitor increases the voltage to the compressor start winding causing the compressor to run fast enough to reach the 75 of its normal rpm during the start up Compressors operating with a start capacitor will cycle on overload if the capacitor becomes inoperative When this happens the capacitor is no longer able to provide the compressor with the necessary voltage to speed up its initial rpm The compressor start winding will never bring the unit to its initial start up rpm required for its run winding to take over The start winding remains in operation until it overheats causing the overload protector to shut off the compressor power When it cools enough power to the compressor is restored by the overload protector bimetal the compressor start winding becomes energized without being able to provide the motor with adequate initial speed It then heats up and the short cycling cycling on overload conti
320. iven point it cuts off power to the compressor When the pressure in the evaporator rises to a predetermined setting the control reconnects power to the compressor the compressor resumes running and the cycle is repeated This control device is often used in drinking fountains and other units where a constant temperature is needed a Be Combination Lew and Lo High Pressure Cabral mmap sap age Comaedhed Eo Sect iun Lina Figure 93 merew Curt wt mesttisgi Until the pressure in the suction line gets high enough to flex the diaphragm the unit remains in the off cycle NOTE It is normal for a refrigeration unit to fail to start after opening the sealed system The low pressure control reacts to the abnormal pressures created by opening the system by having the bellows within the control keep the circuit to the compressor open It can be restarted by manual operation of the tripping switch Lift the bellows tab with the blade of a screwdriver at arrow in fig 93 for a few seconds time depends on the size of the unit DO NOT operate the control at any other point or it will be damaged There are two adjusting screws on top of the control One for the cut in adjustment and one for the cut out As the adjustment screws are turned an indicator moves up or down a scale calibrated in pounds See fig 93 Cut in refers to the pressure at which the compressor resumes operating Not warmer than that point
321. k i e a relay a timer a heater etc 4 The means to control the current flow switches circuit breakers thermostats resistors pressure controls fuses etc Since current is measured in amperes the measuring device is called an ammeter A flux type meter is widely used See figs 71 and 72 and p 305 The device to measure electromotive force voltage is called a voltmeter See pages 298 and 299 An ohm is the unit of measurement of the amount of resistance to the flow of current in a circuit Any resistance slows the number of electrons passing any given point An ohmmeter is used to measure the amount of resistance in a circuit There are pocket size combination meters on the market today that measure volts ohms and amperes see p 303 A load can become energized only when it is in the path of a completed electrical circuit Again a complete circuit must have the four elements power also called potential in some books uninterrupted conductors wires the load and the means to control the flow of current Resistors are used in many circuits to control the flow of current They are used to reduce the amount of energy going to a particular part of a circuit or to a particular component 292 There are three basic methods employed in the wiring and each one has certain advantages and disadvantages 1 series circuits 2 parallel circuits and 3 series parallel circuits 1 Series circuit Component
322. kin it will cause severe pain and damage to that area Since refrigerant is heavier than air when released it displaces air at ground floor level When handling refrigerant or discharging a unit be sure to provide adequate ventilation By failing to do this the refrigerant accumulates and starts to fill the working space from the floor up Then during brazing the flame breaks down the refrigerant it is exposed to and generates toxic fumes creating a breathing problem with a sensation of burning Should these symptoms ever be experienced leave the work area immediately get some fresh air and wait until the toxic fumes have dispersed There are several types of refrigerant used in residential and commercial refrigeration for different applications They are odorless colorless and tasteless SOME OF THE MOST COMMON TYPES OF REFRIGERANT R 12 is very popular It is used mostly in residential refrigerators and freezers in commercial display cases and in walk in coolers It is colorless more or less odorless and boils at 21 7 F This substance is nonflammable noncorrosive and nonirritating It is sold in various sizes of cylinders and in 12 oz cans The containers are color coded white R 22 is used mainly in refrigeration installations that operate with low evaporating temperatures and also in air conditioning units With a boiling point of 41 F it produces low temperatures without having to generate below atmospheric pre
323. l control is to automatically maintain proper water level in the ice flaker Proper water level should be horizontal with the center of the AEV See fig 131b You must use high and low side pressure readings water and Exp h l h V l m J Frost Lina to Evaporator Euction Line Flare air temperatures the frost line the sight glass plus general conditions of cleanliness to assess the refrigeration system status when making any adjustments The location of the frost line can be very helpful in determining proper operation of the refrigeration system The frost line is lowered by higher than normal water temperature or higher ambient air temperature and also poor refrigeration system efficiency Ideally the frost line should be seen on the flare nut attaching the evaporator to the heat exchanger after the unit runs for at least fifty minutes making ice flakes continually See fig 131a To locate the frost line 1 remove the side panels and 2 remove the black insulation over the flare nut and suction line by cutting it with a knife save the insulation as it must be replaced In dry areas where a frost line may not be visible moisten the suction return line with a damp cloth to make it appear Turn the AEV adjustment screw clockwise to move the frost line toward the heat exchanger and raise the suction pressure Turn the Figure 1315 Expansion Valve 35 P3048 pA3
324. l heat HR 1 or HR 1 and HR 2 be energized without the compressor running No The compressor is energized when RVS is energized Assuming the AUTO switch is closed what other switches on the wall thermostat determine if the heat pump operates in the heating or cooling mode The HEAT or COOL switch and the thermostat setting How many line voltage load circuits are shown in the diagram Eight CH OFM RVS IFM and C circuits compressor and two outside heater circuits Thermostat TH 1 and the HEAT switch are closed and the fan switch is set on AUTO name the switches that must be closed to energize the indoor fan motor in that case what other loads will be energized in the circuit s LP RVR relay and its contacts within the relay Other components energized with the thermostat at this setting are CR RVS OFM C and the compressor Thermostat TC and the COOL switch are closed and the fan switch is set on AUTO position Name all the other switches that must be closed to energize the CR control relay LP Thermostat TC and the COOL switch are closed and the fan switch is set on AUTO position name the electrical components that are energized assuming that all pressure controls and the IT thermostat are closed CR IFR OFM IFM C and the compressor Manual thermostat TH 1 the HEAT and AUTO switches are closed and assuming all electrical components are functional explain the step by 13 14 15 16 17 18
325. l of the freezer compartment The hole for the drain tube is behind the panel at the bottom of the compartment Air is moved from the bottom of the freezer up through the evaporator coil and into the fresh food compartment The temperature of the fresh food compartment is controlled by a damper knob in that compartment AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 21 In units with the freezer compartment on top the evaporator is placed either in the back or on the bottom of the freezer An evaporator fan forces cold air to the fresh food compartment through a damper In frost free refrigerators the freezer air temperature runs between O F and 10 F and the fresh food compartment temperature ranges between 38 F and 45 F see fig 3 6 and 9 CHEST TYPE FREEZERS Chest type freezers have an important advantage Since cold air is heavier than warm air it has more of a tendency to stay in the bottom of the freezer and not spill out each time the door lid is opened Consequently a lot of moisture does not accumulate in the cabinet See fig 10 Figure 10 CHEST TYPE FREEZERS Due to this fact chest type units are manually defrosted as defrosting is usually not needed more than once or twice a year To defrost the freezer remove the food from the freezer and wrap it in newspaper to keep it from thawing Unplug the unit or engage the defrost switch usually located in the lid or rim of the cabinet The water from def
326. l panel and compressor compartment access A ten inch clearance is required for the air inlet tothe outdoor coil around the perimeter of the unit A minimum of five inches should be maintained between the top of the unit and overhead obstructions Figure 177b 272 Figure 177C air Retura Duci with hisar grilla TYPICAL AIR SUPPLY DUCT LAYOUTS A TYPICAL SELF CONTAINED ROOF MOUNTED HEAT PUMP UNIT Cool air is blown into the conditioned area through the supply duct in the ceiling and drawn back into the unit from the air return duct Ducts could either be in the ceiling or at the top or bottom of the walls There should be about 15 F difference between the chilled air supply and the return duct o E n 9 Lr gt D m CEILING OR WALL During the heating cycle the air temperature from the supply duct MOUNTED DIRECTIONAL should be about 90 F depending upon the ambient temperature AIR GRILLES AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 273 INSTALLING A THREE PHASE COMPRESSOR The installation of a three phase compressor is a rather simple job since three hot wires make a three phase power supply The power supply lines should be hooked up directly to the three compressor terminals Since the compressor consumes the most power during the start up the power supply line having the highest voltage must be hooked up to the compressor terminal marked S See figs 38 and 39 ag
327. late will void it For compressors that require capacitor s to operate figure 36 illustrates a testing cord that can be easily made You must use fourteen gauge or heavier wire It shows wiring to the compressor terminals a run capacitor a start capacitor and a momentary contact push button switch If the compressor AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 57 being tested does not require a run capacitor or a start capacitor either one may be left out of the circuit Consequently the test cord should be made with quick disconnect fittings and adapters Btart Capacitor Compressor 3 s Terminals PNE Damnbact Sei teh Run Capacitor A TEST COORD ECLIUPPED WITH CAPACITOR ADAPTERS LOCATING A COMPRESSOR INTERNAL ELECTRICAL DEFECT WITH AN OHMMETER When the two ohmmeter probes touch any two compressor terminals the meter should register an ohm reading Otherwise the compressor is defective and it must be replaced When the ohmmeter probes touch a single terminal and the housing ground the meter should register a no continuity reading an open circuit an infinity reading a figure 8 on the meter lying on its side otherwise the compressor is shorted and it must be replaced Scratch or sand the paint off a small spot on the compressor housing to get a good contact CHECKING A COMPRESSOR MOTOR WITH AN OHMMETER Disconnect the unit from the power source Remove the compressor terminal cover Remove th
328. ld a defrost timer be located in a household refrigerator or freezer p 76 How is a timer for a residential unit tested pp 76 77 79 What requires extra attention when replacing fan motors p 85 How many ways are there to test a capacitor p 91 When is a hard start kit required to be installed p 63 What is a unit of capacitance p 89 How can cracked refrigerator door liner be repaired p 101 How do you check for leaks in a door gasket p 100 Where are commercial air coil thermostats installed p 89 Where is a thermostat sensing bulb attached p 94 What precaution should you take with the sensing bulb line p 94 What is the maximum permissible voltage drop for a unit that operates on 115 VAC p 52 What instrument is used to test a power cord p 102 Why do fan motors for commercial units come with longer shafts p 85 What is the function of timer terminal 1 on a Philco residential refrigerator p 79 PROCEDURES FOR THE EVACUATION AND CHARGING OF COMMERCIAL AND RESIDENTIAL REFRIGERATION UNITS This section covers the most common techniques of opening evacuating and charging a sealed system in addition to repairing leaks in commercial and residential refrigeration units Tu EE L P dm x a Pu T ie E I MITT 107 108 PREPARING THE SYSTEM FOR CHARGING There are many repairs that require the opening of the sealed system in a refrigeration un
329. ld be one half inch for three fourth inch tubing the length of the swage should be three fourth inch etc Figure 22 illustrates two pieces of tubing where one has been swaged to create a connection with the other There are two types of swaging tools available the lever type and the more popular punch type fig 23 Different sized collars and punches _ Heat tubing with Figure 21 are used to swage the various sizes of _ tre Yellow flame tubing To use the punch type insert the tubing in the correct size hole in the anvil block Select the proper size punch eae Int and insert it in the tubing Hammer it before applying flux down into the tubing until it reaches the Heat tubing starting one half inch to proper overlap distance one inch from the joint Move torch toward joint and heat that area briefly DISASSEMBLING A BRAZED JOINT Concentrate heat a little above the joint until joint turns cherry red and apply flux around joint Correct Brazing Technique for Joining Copper Tubing It is easy to take brazed joints apart using the same method by which they were joined Heat the joint with a torch until it becomes cherry red in color and then grab the tubing near the joint with a pair of pliers and pull it apart 40 It will be necessary to disassemble the tubing for replacement of the compressor or any other part in the sealed system Before removing the old part you can use this method to discon
330. ld the torch in one spot Keep it moving until the joint turns cherry red This color indicates that the joint has reached the temperature at which silver alloy flows 1 145 F 4 Apply the brazing alloy at the top and allow it to seep into the heated joint Since alloy always flows toward heat hold the torch at s 1 Teflon Tape the back of the joint to let the alloy flow into 2 Flux the joint and fill it up 3 Brazing Rods 4 Inspection Mirror 5 Coolthe joint with a piece of wet rag then use hot water and a brush to clean it This is epuoj J Iwe uonelod1o5 sjonpoid JeuSeM Jo Ase1ino AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 39 important because any remaining flux will tend to corrode the tubing and block a leak that might show up CAUTION Always buy alloy that does not contain cadmium Cd as cadmium fumes are highly poisonous If the brazing alloy contains any amount of cadmium do not inhale the fumes or allow them to come in contact with your eyes or skin Swaging copper tubing Swaging is a process by which the end of one tube is enlarged to allow the end of another tube of the same diameter to fit inside for brazing This method of joining two lines of the same diameter eliminates the use of fittings As ageneral rule the length of the swaging or overlap should equal the outside diameter of the tubing being joined For instance when joining one half inch tubing the swaged overlap shou
331. lem AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 265 HEAT PUMPS In the evaporator coil of a regular air conditioning unit the vaporizing refrigerant absorbs heat from the conditioned area This heat is then transferred to the condenser where it is radiated to the outside environment In other words the heat picked up from the inside is transferred to the outside Heat pumps are basically like regular air conditioners with the difference that they can reverse the action of the evaporator and condenser simultaneously by reversing the direction of the refrigerant flow When this happens the evaporator becomes the condenser and the condenser coil becomes the evaporator This is made possible by using a reversing valve When the reversing valve is de energized it connects the outside coil to the suction line of the compressor changing it to an evaporator and the inside coil to the discharge line of the compressor changing it to a condenser With the evaporator now on the outside the unit picks up the available heat from the ambient air and transfers it to the inside coil now the condenser and gives up that heat to the conditioned area A heat pump unit has a few extra components as compared with those found in ordinary air conditioners 1 Areversing valve which is also known as a four way valve See figures 103 103a and 103b When the heating switch on the control panel of the unit oron the wall thermostat is turned on
332. level Replace faulty compressor Check and correct as necessary Check and replace if necessary Check for voltage drop Check and replace as necessary Check against wiring diagram Check for voltage drop Check for restrictions or overcharge Check for open TEV insufficient compressor system overcharge Check and replace as necessary Check capacitance replace if defective Check and repair or replace Repair or replace compressor Check and correct cooling system AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 355 Problem and Possible Cause Windings shorted or grounded Overload protector wired wrong Run Capacitors Burn Out Excessive voltage Water shorts capacitor terminals Low voltage rating on capacitor Relays Burn Out Line voltage too low Line voltage too high Relay vibrates Improper relay Improper run capacitor Unit short cycles Start Capacitor Burns Out Improper capacitor Water shorts out terminals Voltage rating too low Sticking contacts on relay Operates too long on start winding Unit short cycles Faulty relay Remedy Check windings with ohmmeter replace motor if defective Make sure components are not wired to the wrong side of the protector Check line voltage should not be over 10 above motor rating Protect capacitors from moisture Install capacitors with correct voltage rating Correct line voltage to not less than 10 below
333. long the direction of its shaft boiling point The temperature at which any liquid boils and changes to vapor Boiling point of water at sea level is 212 bending spring A tube in the form of a coiled spring used in bending tubing back pressure Another term for low side pressure bimetal strip A flat spring composed of two different metals soldered together which is flexed by temperature changes 419 420 bin thermostat A thermostat or lever installed in the storage compartment of an ice making machine to stop the production of ice when the bin is full capacitor A device for holding or storing an electric charge used with compressor motors to boost starting and or running efficiency capillary tube A slender tube having a very small bore Its small diameter maintains a pressure difference in the sealed system as well as controlling the flow of refrigerant into the evaporator when the compressor runs check valve A device installed in the sealed system that allows refrigerant to flow in only one direction charge The amount of refrigerant put into a sealed system circuit electrical The path of electric current closed circuit An uninterrupted path for electrical current compressor A motor driven pump that draws vapor refrigerant from the evaporator compresses it and forces it out under high pressure to the condenser cooling coil Another name for an evaporator coil cold The absence of heat condensation
334. ls of a closed switch reads volts because no potential difference is created 2 The two terminals of an open switch reads voltage 3 The two terminals connecting a load to the power produce a voltage reading 4 The two sides of a broken wire registers a voltage reading 5 Thetwo terminals of a blown fuse gives a voltage reading 6 The two terminals of a good fuse produce a zero reading because no potential difference is created 7 The two sides of a load whether or not it is operative produce a voltage reading Make sure to set the conventional type voltmeter on the proper scale for the expected voltage to prevent damage to the instrument These or similar instructions are included with all new meters As mentioned earlier there are also pocket size digital multimeters that are inexpensive With these handy meters the necessity of selecting a particular scale is eliminated as they produce a direct reading up to their maximum capacity These meters are much more convenient and are pictured in pages 303 and 305 300 In a 110 125 volt receptacle expect the following voltage readings Between terminals H and N 110 125 VAC Between terminals H and G 110 125 VAC Between terminals N and G 0 VAC Typical In a 220 277 volt receptacle expect the following voltage readings 373 11 Between the two H terminals 220 277 VAC Between either H terminal and the G terminal 110 125 VAC Hist Tarminaim Ina three phase 250
335. ls to the coolest position nothing works the fan and compressor remain inoperative The position of the switch is changed from AUTO to ON while the switch remains on COOL Nothing happens the fans and compressor fail to start What components should be checked Check the transformer primary lines for 230 VAC Check the transformer secondary lines for 24 VAC and check for a tripped circuit breaker or blown fuse In answering a no cooling complaint on a central air conditioner after the Wall Thermostat is adjusted to its coolest setting the levers on AUTO and COOL the unit starts operating but the compressor short cycles operates for four or five seconds then stops then restarts after two or three minutes for only four or five seconds What electrical components should be checked Check the compressor for a grounded or disconnected run winding or for low voltage at the power source 336 QUESTIONS AND ANSWERS ABOUT THE SCHEMATIC WIRING DIAGRAM FIGURE 194a How many controls are there in the compressor circuit Five control relay contact high pressure control low pressure control internal thermostat and the compressor If the control relay becomes inoperative how many components will not function Two the compressor and the condenser fan motor What controls the compressor crankcase heater The control relay coil What controls the indoor fan motor Indoor fan relay coil If the low pressure control opens what c
336. lso connected to the discharge line Its main function is to shut down the unit when the pressure in the discharge line rises to a dangerous level The cut in and cut out settings on the control are manually adjustable When the pressure goes higher than a preset cut out point a switch within the control snaps and shuts off the power to the compressor If the cut in and cut out settings are adjusted too close the unit will short cycle If the unit is overcharged or if a restriction occurs in the sealed system the discharge line pressure will rapidly rise higher than normal causing the high pressure control to react and shut down the system During the off cycle the pressures in the sealed system tend to equalize the head pressure decreases and the low side pressure increases As soon asthe discharge line pressure drops to a cut in point the switch within the pressure control snaps closed and restores power to the compressor causing the unit to resume operation As long as this happens at short intervals the short cycling continues See the pages concerning pressure controls for more details In a particularly restricted system the unit will short cycle as a result of the reaction of the low pressure control to the lower than normal pressure in the suction line The compressor keeps drawing from the suction line It creates partial vacuum in the system from the restriction and keeps pumping into the discharge line against the restriction
337. luding the side of the compressor that discharges hot gas the condenser the filter drier and the receiver high side float control A control mechanism that maintains a constant level of liquid refrigerant in the high pressure side of a refrigerating unit AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 425 high side pressure Pressure in the high side of a sealed system high side pressure control high pressure cut out A switch that limits the high side pressure of a refrigerating unit high vacuum pump The apparatus used to create a high vacuum in a sealed system The pump causes a drop in pressure to vaporize and draw out moisture from the system horsepower The unit of power equal to 746 watts or 550 of work per second hot gas bypass The tubing system to transfer hot vapor refrigerant from the condenser to the low temperature side of a refrigerating unit insulation electrical Encloses electrical conductors like wires with a nonconducting material to prevent unintentional grounding insulation thermal Materials that are poor heat conductors The liners of cold compartments and freezers latent heat Heat not measurable on a thermometer which causes the change of state of a substance lead leed That portion of electrical wiring connected to a component leak Escape of refrigerant from a sealed system leak detector electronic type A battery operated instrument that emits a high pitched sound when i
338. lways get a voltage reading when placing the voltmeter probes across a load 120 WAC 0 The voltmeter registers 120 volts when placing the probes across the closed switch A B this means there is an interruption between A and B A good switch that allows current to pass through when it is closed placing a probe on either side should register a volt reading because current is not interrupted between its terminals to create a potential difference 302 Since there is a voltage reading this will mean the switch is defective because power reaches one terminal of the switch but because of a break in the circuit inside the switch power cannot reach the other terminal even with the switch closed With the voltmeter probes across a good switch in the ON position the meter should read zero voltage No potential difference PROBLEM 2 In the circuit below power is on and there is no heat When the circuit is checked with a voltmeter A B shows a 0 volt reading C D shows a voltage reading CONCLUSION Since power reaches the heater but the heater does not heat the heater element is bad shorted and burnt PROBLEM 3 The next circuit below is energized and has no heat When the circuit is checked with a voltmeter A B shows 0 volts C D reads voltage E F also shows 0 volts CONCLUSION Switch C D is defective or open because voltage is stopped there and cannot pass un TAC
339. ly an optimum charge will be 90 to 95 of the original weight of the R 502 charge It is recommended that you start with a 90 charge and increase charge as necessary to obtain optimum operation Since the liquid composition in the cylinder is different from the vapor composition it is important that only liquid be charged into the system to ensure the correct refrigerant composition Liquid is withdrawn from the bottom of the cylinder through the dip tube only when the cylinder is in the upright position The initial charge should be added to the high pressure side when the unit is not running When the cylinder pressure is equal to the pressure in the system the remainder of the charge may be added to the suction side with the compressor turned on Since you should remove only liquid from the charging cylinder some compressors may be damaged if liquid HP refrigerant enters so care should be taken to introduce SUVA slowly to allow time for it to vaporize You may find it necessary to install a throttling valve to ensure that only vapor refrigerant enters the compressor 410 STEP BY STEP RETROFIT INSTRUCTIONS FOR SUVA HP 80 AND HP 81 REFRIGERANTS 1 Remove existing R 502 charge from the system If the amount of charge in the unit is unknown weigh the R 502 removed 2 Drain the existing oil charge from the compressor and measure the amount drained Small hermetic compressors may be physically removed from the system to drain oil
340. mally closed is the most widely used two way valves are manufactured to be normally open when the coil is de energized See figure 98c for an example of a two way valve 150 The three way valve has a connection which is common to either of two different outlets and controls refrigerant flow in two different lines They are used chiefly in commercial refrigeration units for heat reclaiming applications hot gas defrost and discharge gas unloading applications See figure 98d for an example of a three way valve The three way valve has its common inlet attached to the compressor discharge line The other two outlets connect to the normal condenser and the auxiliary condenser as shown in figure 98e 98 T m og Dierk Vaive liest RHaclaim Val L c E ee d iraa aaber dios rebig ah ma pen a bum ronwhkerasemp bi waa The ieii ke oc a acad hrie When the solenoid coil is de energized the pilot line to the suction side of the compressor is closed Discharge gas pressure escapes through the bleed port into the top of the piston and drives it downward closing the bottom seat This allows discharge gas to flow to the normal or outside condenser Energizing the solenoid opens the pilot line to the suction side of the compressor and permits the discharge gas pressure on top of the piston to escape to the suction line The discharge gas pressure below the piston now cause
341. many residential units For specific problem found problem low side pressures see the Tech Master mentioned on page 112 See fig 79 Check low side pressure An indication of a partially restricted Low side pressure tem is that the last part of the dri Below 0 lbs in system is elas par of the drier Low side pressure or the capillary tube is cold to the above 0 Ibs ir touch or sweating Charge the unit with Refrigerant type used in unit and observe condenser 2 Run compressor efficiency test see p 67 51 Compressor OK Charge the system until Vacuum system replace the low side pressure filter drier and recharge reads about 7 psi General temperature rise across condenser Y No temperature change across lower two third of condenser Nothing wrong with refrigeration 3 system recheck box 1 Run a leak detector test on the sealed system particularly on all joints Find and repair leak see fig 82a Vacuum see fig 84 Replace drier see fig 76 and Replace Compressor recharge fig 80 128 A TEST OF KNOWLEDGE OF REFRIGERATION IN GENERAL 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 What purpose does a heat exchanger serve p 126 Are defrost timers used in cycle defrost type refrigerators pp 17 18 What is the temperature range in the fresh food compartment in a residential refrigerator p 16 What is
342. me Shia wall saison pay kr ball it has compressor a sight gia aed contra to alia of Araki wapor A pump cheue though penne bo purthy i iria 0 that It cam be reused or al disposable conisiners hn from 50 fe 15 Dottie makes easy bo memur and replace od hong fram the yabem Refrigenaar is 27 or cena Countess of dais Seeder SPA opi 140 PRESSURE CONTROLS IN COMMERCIAL REFRIGERATION In residential refrigeration units a thermostat controls the temperature by connecting and disconnecting the power to the compressor This type of cold control reacts to the temperature changes There is a correlation between the pressures created in the sealed system and the temperatures produced by the vaporizing refrigerant Commercial units take advantage of this relationship by employing pressure controls that govern the operation of the compressor to regulate the temperature in the unit by controlling the pressures inside the sealed system Serving a two fold purpose they regulate the temperature and at the same time protect the system from pressures that become too high or too low They do this by disconnecting and reconnecting the power to the compressor motor There are three types of pressure controls utilized in commercial refrigeration They regulate either the high or low pressures or act as a safety device
343. me outlet fittings as CFC 12 R 12 cylinders when used for 406 stationery refrigeration equipment 134 30 pound cylinders used for automotive air conditioners have a CGA 167 outlet valve to avoid mixing R 12 and HFC 134A at the time of servicing automotive air conditioners The 123 pound containers are furnished with a two way valve to remove SUVA 134A refrigerant either as liquid or as vapor from the cylinder without the need to turn it upside down On the side of the valve the liquid handwheel is connected to a dip tube reaching to the bottom of the cylinder The vapor wheel is placed on top of the valve Both wheels are distinctly marked as liquid or vapor For information pertaining to larger containers contact DuPont Chemicals at 1 800 441 9442 CHARGING AND FILLING SAFETY MEASURES 1 Remove all of the remaining refrigerant from the system or cylinder if you are filling one 2 Make sure that vacuum lines are free from restrictions that might produce discharge pressures above 15 psig 205 kPa and cause the formation of combustible mixtures 3 Neverfill refrigeration equipment or cylinders when under positive air pressure They must be evacuated before filling 4 Stop charging equipment or filling cylinders before the pressure goes above 300 psig 2170 kPa 5 Cylinders filled with SUVA 134A refrigerant should be periodically analyzed for air content Figure 221 An automatic programmable charging meter de
344. ment stop the meter should register an open circuit reading If not the timer should be replaced 7 Place the two ohmmeter probes on terminals 1 and 2 and continue turning the cam A zero reading should be registered on the meter until aclickis heard Stop The meter should register an open circuit reading If not the timer should be replaced 8 Setthe ohmmeter on the RX1000 scale and zero it 9 Connect the ohmmeter probes to the timer terminals 1 and 3 The meter should register a continuity reading Otherwise the timer motor is bad and the timer must be replaced Thistest can determine if the timer has any electrical defects Timers can also develop mechanical problems Occasionally a defrost timer motor freezes in one particular cycle and it no longer advances because of mechanical problems or a short or a disconnection in the timer motor To test the timer for mechanical problems turn the cam very slowly clockwise If you feel any snag anywhere while turning it the timer should be replaced While the timer is disconnected from its electrical wires visually check all of the terminals for burns If there are any brown spots or burns on any ofthe terminals replace the timer When connecting the timer terminals to the system make sure every connection is secure Tighten loose connections and replace broken or frayed wires CHECKING THE TIMER MOTOR BY DIRECT CONNECTION This test can determine if the timer motor has any elect
345. mer p 242 Where are contactors installed p 245 What is an A coil p 274 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 285 28 Where is an A type coil or slant type coil installed in a central air conditioning unit p 274 29 What are the two major causes for a contactor becoming inoperative p 245 30 What are the two basic differences in wall thermostats p 256 CORRECT PIPING METHOD FOR REFRIGERATION AND AIR CONDITIONING Liquid line size It is important to use the proper size tubing A liquid line that is too small causes excessive pressure drop reducing the volume of liquid refrigerant that flows into the evaporator resulting in reduced unit cooling capacity It is a good practice to use about 20 oversized liquid line tubing Every added tee valve and 90 elbow adds to the resistance exerted against the liquid refrigerant flow Figure 178d shows the increased length of tubing equivalent to the resistance offered by a valve tee or 90 elbow Figure 178e shows the amount of liquid line charge in pounds per foot of tubing that has to be calculated when designing a sealed system As stated earlier a vertical rise offers some increased resistance and consequently a pressure drop in the liquid line As arule of thumb one should consider 1 2 psi pressure drop for every foot of rise This is due to the weight of the refrigerant that reduces the velocity of the up flow Figure 178f shows the amount of pressu
346. mmercial compressor motors asolid state overload protector is placed within the compressor and connected in the circuit This type of overload protector is referred to as the thermistor type Hermetic compressor motors that are equipped with internal overload protectors are replaced when the overload protector becomes defective USE rol bos Cylinder Fod A EMIDBATTIC TERE TONAFEETIDA Themes ehai fy cornpeersm aem eee ee kw mas dinm Ph 7 aunbiaresi The atin Jf ao wax are mil lj Ther Me ied type os n aum a hcal f 1 an he Fou pen ther peeked meam PRESS P ankcasa ai Y Slams riga 114 j darn aban D Peed d 174 COMPRESSOR BURNOUT Compressors often burn out by overheating caused by above normal head pressures Laboratory tests have proven that presence of air dirt and moisture in the sealed system contribute to this condition Compressors are cooled by bypassing cooled oil mixed with vapor refrigerant returning from the evaporator over the windings When the compressor operates while the system is undercharged or out of charge insufficient cooling of the compressor motor can cause a compressor burnout Compressor motors can also overheat and burn out by excessive current flow through the windings caused by low voltage supply or a binding compressor If the temperat
347. motor rating Correct voltage to no more than 10 above motor rating Check relay operation mount firmly Install relay recommended for unit Install capacitor with correct mfd rating Correct cause of short cycling Install capacitor with recommended voltage and mfd rating Protect capacitor terminals from moisture or relocate capacitor Install capacitor with recommended voltage and mfd rating Clean contacts or replace Replace faulty relay reduce start up load increase voltage if too low Correct cause of short cycling Replace relay TROUBLESHOOTING REFRIGERANT FLOW CONTROLS This section covers refrigerant flow controls consisting of a troubleshooting guide for the fluid flow problems troubleshooting the solid state expansion valve electric valve and servicing cooling towers The author wishes to express his deep appreciation for the most generous contributions of ALCO Controls Division of Emerson Electric Company and Eaton Corporation Appliance and Specialty Controls Division without which the preparation of this portion of the book would not have been possible The material in this section represents the latest available research data and technology for troubleshooting refrigerant flow problems including the electric valve and water cooled condensing equipment 357 358 9 00 5 OY gt gt o
348. mount rests flush on top of t a gear motor 2 Place shaft seal with carbon faceup spring down over output shaft and push gently downward until seal nests in recess of the shaft seal mount 3 Place rubber coated ceramic Canten of WIBHIE Cone seal important ceramic face Schsumbung finas down over output shaft and push down until seal rests on carbon face of the output shaft seal Lubricate rubber on ceramic seal with number 06195 rubber lubricant 4 Place flat washer over output shaft and let rest on the ceramic seal Push down on the washer compressing the spring on the output seal and nesting ceramic seal inside recess of shaft seal mount While holding the seals down in place put lower spacer over output shaft Insert drive pin into hole to hold assembly 5 Place gear motor on its side supporting end of shaft with block and tap drive pin with hammer until fully engaged Pin must have approximately one fourth inch protruding on either side of output shaft Do not use excessive force with hammer resulting in damage to drive pin and or gear motor bearings Iria Pan o T LEID 196 REASSEMBLY PROCEDURE FOR WILSHIRE ICE CHUNKLET FLAKER FCS MODELS After the unit is disassembled check all the parts for wear and discard worn parts Replace bad parts with new authorized parts only See fig 131d Lubricate the inside of coupling number 2 with a light coating of Lubri Plate number 630 AA Place coupling
349. move it Connect the tube cleaner to one open end of the capillary tube by using an adapter fitting then turn the handle to create the pressure necessary to clear the tube In these devices either oil or R 11 is used as a pressure fluid See fig 45b After removing the obstruction from the tube install a new filter drier and silver braze the tube back into the system before evacuating and charging the unit Figure 45b Capillary tubes are not expensive but sometimes they are hard to reach particularly in residential units The capillary tube begins in the compressor compartment in residential refrigerators and freezers runs through the body of the unit and it is silver brazed to the evaporator inlet A lot of work and replacement time can be saved if a blockage can be cleared with a capillary tube cleaner A CAPILLARY TUBE CLEANER WITH ITS PRESSURE GAUGE AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 65 There are some capillary tube replacements on the market called patented tubes Some of them are available with different sized strainers while some are fitted with a calibrated wire inside to control the flow of refrigerant see fig 45c If a new capillary tube is needed it must always be replaced with one having the same inside diameter and the same length otherwise evaporator temperature will be affected For better understanding you should know that there are three types of compressors made today high
350. mpressor start winding cools down the overload protector closes the circuit to the compressor again and the short cycling continues Line voltage may not vary beyond 10 of the compressor specification printed on its nameplate Tanne the urit Thes Peon the poseer ihe ac Fehr it Erster LE RT anat LIO WC ant the ined of mating aui beka fe urit cece on rbad Misaia li cos fis intro Lo high aims oar in cml uwtilitg Zu 13 Bperating Barya 105 Low voltage Inwtsll bar start kit ie Figura Ata aliaga Loc Low for hard mier i Bils me to call electrician or the TES THE ees Frit Equipment designed to operate between 108 VAC and 115 VAC will not operate well when the voltage drops below 98 VAC Should this occur advise the customer to call the power company to remedy the problem as there may be nothing wrong with the unit There are transformers on the market today that can remedy the low voltage problem by increasing the supply voltage Sometimes there are too many pieces of equipment connected to the same receptacle causing a voltage drop below the acceptable range Just disconnect some of the load and reconnect it to another wall outlet AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY HOW TO TEST THE SUPPLY VOLTAGE Set the voltmeter on the proper scale i e on the 110 scale fo
351. mpressor suction power on the outlet of the evaporator and the fact that the capillary tube with its very small inside diameter is placed on the inlet side of the evaporator the pressure in the evaporator is reduced to an average of 3 5 psi in an ambient temperature of 70 F see fig 1 It is these low pressures that cause the refrigerant to boil and absorb the surrounding heat during its change of state essentials 1 and 3 Figure 15 Accumulator Figure 14 Shell Type Evaporators Fin straighteners may be used to straighten and or clean evaporator or condenser fins uoneJodJo pueJyHON JO UOLS Seu1snpu POMEN jo 2 A Simple Flat Type These fan forced type evaporators are used Evaporator in frost free refrigerators and freezers Four of the most common types of evaporators are illustrated above and in figures 3 4 and 5 Figure 5 shows the cycle defrost type of evaporator This is basically a flat aluminum plate with a cooling coil in it About three fourth of this plate is in the freezer compartment while the remainder extends into the fresh food compartment Since fewer loops of the coil are in the fresh food compartment only a small portion of the cold air is produced there but adequate to maintain the proper temperature AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 31 Frost free refrigeration units are equipped with fan forced circulation evaporators in which a fan increases the airflow throug
352. n see fig 216 This is a major time consuming repair and should be done only if a replacement coil is not available 3 Make sure the strainer is clean then disconnect the pipe from the water tower outlet to see if water flows up to that point if not reseal the connection 4 Check the water float by manually pushing it in to see if the problem is the float 5 If not disconnect the pipe from the water regulating valve outlet to determine whether or not water flows up to that point If not the AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 395 source of the blockage must be in the water valve Generally the water cooled condenser is connected to the cooling system by a plastic or rubber hose and a blockage can occur in that short length of hose due to its decomposition Refer to figure 214c for the removal of the water regulating valve A water hammering problem can be remedied by installing a short length of vertical pipe just ahead of the water circulating valve This absorbs the shock of the water after a sudden disruption in the flow As arule of thumb the water temperature should rise about 10 F as it flows through the condenser and absorbs heat To determine the expected unit head pressure add 10 F to 15 F to the temperature of the water leaving the condenser from its discharge line Using the chart on page 124 convert the sum of these temperatures to the pressure shown under the appropriate type of refrigerant
353. n air conditioning self contained air conditioners and split systems 1 Self contained air conditioners are the units in which the compressor evaporator condenser and the blower fans all contained in a single minap Lijani 230 housing A good example of such a unit is a window mounted type air conditioner Also see fig 148 2 Split systems In this system the evaporator and its blower fan s are installed separately from the rest of the unit usually inside the building Automobiles also use this type of system by having the evaporator and its fan in the dashboard in the passenger compartment with the rest of the components under the hood In central air split systems the compressor and condenser referred to as the condensing unit are installed outside of the conditioned area s on a concrete slab or on the roof of the building The evaporator is installed on a wall in an artificial ceiling or in the plenum chamber see figs 156 157 and 158 Figure 135b A inio or ial l rmount npe sanii maranted an tha wall Figure 13 Figure 136a A typical wike bpi alr condirianer imalati The outside shell for the winders or wali maunt unit should be wel sapported AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 231 WINDOW OR WALL AIR CONDITIONING UNITS The type of air conditioner depicted in figures 136 and 137 is usually equipped with a split phase capacitor run SPC motor see
354. n more heat is required for brazing larger diameter tubing p 38 How is a brazed joint disassembled pp 39 40 In what direction does alloy flow while it is being heated p 38 TESTING RESIDENTIAL AND COMMERCIAL REFRIGERATION UNITS This section covers the methods of quickly and easily checking each major component in commercial and residential refrigeration units This knowledge coupled with the information on the troubleshooting charts provides a quick diagnosis of the most common problems encountered in this career field Courtesy of Beverage Air 47 48 THE COMPRESSOR There are generally four types of compressors in use today reciprocating rotary centrifugal and the screw type Some of these compressors used commercially could be belt driven or hermetic The hermetic type has its motor and compressor coupled directly together in a sealed airtight metal housing whereas the others are powered with a separately mounted motor and driven with a V belt s and pulleys All residential and many light commercial refrigeration units are operated with hermetically sealed motors and compressors because they are compact and require little space In heavy commercial and industrial use where large capacity units are required and space is not a problem the separately mounted motors with v belts and pulleys to drive the compressors work well A reciprocating compressor is similar to an automotive engine with a piston
355. n the nd by using ani Ales wrench ther ones with The MT Cee the valer moreg faster dz fr a Hegre jpa ix pened nn ihe nesdis ian the foros rhe needle bren fo pane the tebe Some pening wakes hoe a ming cap which m Gane Erg rd the Eras H peed Then the ki peeved for poring the systern Cope end the par ix discarded Caen mum be raien sans the vaie on i und pag of iow fhe nubila pet d hibit pes The xiheur brareri ippa rest sham tas Go hanoe foe i pace the breed feed leaxpegel mach berger fae dows scree fing Lap feed le Duprtusacr D zi diee EI es S amp cred hep The somber being Ts high and kras fourier pd magnu Peacock Cprsanmean Kors Fass CHARGING A UNIT BY THE AMOUNT OF CHARGE SHOWN ON THE NAMEPLATE CRITICAL CHARGE a Checkthe nameplate on the unit to determine the exact amount of charge This figure is reflected in ounces Some larger commercial units indicate this figure in pounds fig 64b In this case the refrigerant tank must be weighed Subtract the amount of charge and then leave the tank on the scale Charge the unit until the correct amount of refrigerant leaves the tank A more precise method is to use an electronic charging scale See fig 75c b Fill the charging cylinder with the exact amount of refrigerant
356. nals T1 and T2 come in contact with terminals L1 and L2 and complete electrical paths to the compressor motor fan motor s etc There are three pole and four pole contactors used in three phase circuits see fig 152b Figure 23 TTEA TRI INE COMITATO Far 1528 M WM lm mm d In EUN I T A THELEN L que ria ier ie crag 2 Oriri POEET eee Tranier Lasin nl h ar Sager Cheam jeri Pre a Loree 744 maii mi Lamy asam ahdim im iam br agg a aam hrie ed ar app rl prar ter ees irg reirei thee Label and beri adagen The low voltage comes to the contactor coil through the wall thermostat When the wall thermostat is turned off or satisfied the low voltage circuit activating the contactor coil is interrupted causing the compressor to shut off AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 245 HOW TO CHECK A CONTACTOR Contactors are magnetic switches that are used in applications where simultaneous openings and closings of different line circuits are required They can become inoperative by a burned point s or by a burned coil 1 During normal operation the contactor points may become pitted and or charred by an electrical arcing When this happens the metal points become incapable of completing a particular circuit and the component s in that circuit will not function When a contactor point becomes charred only
357. nd many refrigeration manuals refer to high and low side float systems units using these systems are very seldom encountered The low side float system was more popular in the early years of mechanical refrigeration It is also called a flooded system This low side float mechanism is a part of the evaporator The vapor refrigerant is drawn through the suction line to the compressor then discharged as a high pressure gas into the condenser where it is cooled and changed to its liquid state Liquid refrigerant flows into the evaporator through a valve that operates in conjunction with a float The lower portion of the evaporator is occupied by liquid refrigerant while the portion above the float is filled with vapor When the desired low temperature is reached the compressor is de energized and this operation stops Flooded systems are easy to service and are very efficient because the cold liquid refrigerant wets the surface of the evaporator causing a rapid heat transfer These systems require a motor that can start under heavy load because the pressures do not equalize during the off cycle They also take a larger than average refrigerant charge because liquid refrigerant occupies both the liquid receiver tank and the evaporator About the only service these units need is the replacement of the needle valve HIGH SIDE FLOAT SYSTEM Fig 110 Since in this system the evaporator is always filled with liquid refrigerant this is also con
358. ndary winding and it is referred to as a step up transformer For example converting 110 VAC to 120 VAC Since most relays and contactors coming up in future pages operate on 24 or 40 VAC in the central air conditioners step down transformers are installed in their electrical circuits to convert the 110 VAC 220 VAC etc to that 24 or 40 VAC The primary winding of the transformer is hooked up to the power line and the secondary winding terminals are always 242 connected to the load controls such as wall thermostats electronic timer defrost boards contactors relays etc 1 THE OHMMETER METHOD OF CHECKING A TRANSFORMER Disconnect power from unit Disconnect the power Disconnect the transformer from the unit Setthe ohmmeter on its lowest scale Touch the probes to the two primary wires terminals The meter should register a continue reading otherwise replace the transformer Next touch the probes to the two wires coming out of the secondary winding or terminals You should get an ohm reading as above if not replace the transformer NOTE There may be more than one set of wires or terminals connected to the primary and secondary windings This means that the transformer primary winding is usable on different voltages i e 110 VAC or 220 VAC also the secondary winding produces more than one voltage Each set is individually color coded and the set not being used is tied off and insulated from the rest The in
359. nded to shut down when only one component becomes de energized or defective When this happens current continues to flow through the other paths to complete the circuit This type of circuit is found in household refrigerators For example when the refrigerator lamp becomes de energized when the door is shut other components such as the motor compressor etc in the system stay energized Note that in the simple parallel circuit of figure 180 the broken wire near the motor does not interrupt the current flow to the rest of the circuit The heaters the fan and the reversing valve remain active because current can still flow through these components and complete its unbroken paths Heater 2 i fe ees A PARALLEL CIRCUIT ra Reversing Valve E Figure 180 In parallel wiring if one segment of the circuit is turned off other components stay unaffected because there are still unbroken paths through which current flows 3 Series parallel circuit As the name implies itis a combination of series and parallel circuits In this type of wiring any one load component or a set of loads can be controlled by different switches resistors 294 solenoids etc while the rest of the system remains unaffected In figure 181 below circuits A B C D E F and G H are individually series circuits If the fuse blows the entire system will become de energized If the solenoid burns out it will cause the fan motor to s
360. ne Liquid line Filter drier Duct work A type evaporator coil Expansion valve 9 Condensate drain 10 Gas heating element 11 Blower 12 Air handler 9 E 5 X oO a 7 n o c 3 o 2 7 o Figure 156 i i A SPLIT TYPE AIR CONDITIONING SYSTEM In a typical split system the compressor and condenser are installed together called the condensing unit outside the structure with the evaporator in the inside as opposed to the console system where all components are housed in a single unit The condensing unit is usually installed outside on a concrete slab or on the roof with the evaporator on the wall in the air handler in an attic or in an artificial ceiling with a fan circulating the air through the cold evaporator fins inside the conditioned area See figs 156 157 and 158 250 The condensing unit outdoors circulates the air to cool the condenser coil and the blower in the plenum chamber circulates the air through the evaporator coil to provide chilled air Figure 158 er mauus conditioner with a wall mounted evaporator unit A TYPICAL CONSOLE CENTRAL AIR CONDITIONING UNIT Figure 156a AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 251 There are three types of evaporator coil used in centr
361. nect the tubing CAUTION Before applying heat to any joint it is imperative to evacuate all the gas Freon in the system To do this use an access valve Refer to figs 45f and 79 Figure 22 0 dt TYPICAL SWAGED FITTING Figure 23 When a punch type swage is used place the copper tubing in acorresponding hole in the anvil block Insert the punch in the end of the tubing and hammer it down until the desired expansion is obtained A typical brazing outfit acetylene and oxygen tanks pressure gauge acetylene regulating valve and torch Above a service valve wrench Courtesy of MALCO Products Inc Instead of connecting tubing by swaging before brazing special couplings can be used to join tubing of similar or different sizes by silver brazing Figure 24 illustrates some of these couplings They are available in most tubing sizes uoneJodJo xds UOISIAIG Asa34no5 Typical Couplings 1 2 and 4 Reduction 3 and 13 Straight with stop 5 Straight without stop 6 7 and 9 90 elbows 8 Tee 10 11 and 12 45 elbows AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 41 Flared connection This is a metal to metal connection without the use of a solder To create a flared connection the ends of the tubing to be joined should be cut straight and square with a tubing cutter fig 17 to prevent an off center and consequently le
362. nergize IFR and CR relays and takes the unit into the cooling cycle The RVR reversing valve relay stays de energized and the unit cools The outside coil now acts as a condenser and the inside coil acts as an evaporator hence there is no need for heating the outside coil When the unit is in the heating mode every ninety minutes the DTC defrost timer takes the unit into the defrost cycle for a maximum time of ten minutes 346 10 11 12 QUESTIONS AND ANSWERS ABOUT THE WIRING DIAGRAM ON PAGE 344 How is the reversing valve solenoid energized When the reversing valve relay closes its normally open contacts Assuming all switches on the C contactor coil and CR control relay coil are operational the wall thermostat is set on COOL and the TC thermostat is adjusted to its lowest setting the compressor fails to start What components will require checking CR C HP LLP and the compressor What switch es must be closed to energize the heater relay HR 1 Heat switch on the wall thermostat TH 2 and ODT1 What indicates that the transformer is burnt out and no longer functional Nothing in the system will work and the crankcase heater will stay on all the time When the thermostat TH 1 closes what determines the number of supplemental heater strips that are energized The inside temperature Assuming all the loads are operating and the wall thermostat switches are correctly set can the second stage of the supplementa
363. nergized eel Liar Energi med Lima Cardi MWan Ribbed a 4 Ei bbe Fan white Capacitor mlige Hed Dok ver Load is roter EE hasier Leek Black Compresmor Kun Capacitor White oS Main Switch Figure 190b Figures 190b and 190c are typical schematic wiring diagrams of a wall window air conditioning unit with an external overload protector In figure 190b the unit is in the cooling mode with the fan operating on low speed In figure 190c the unit is in the heating mode with its fan operating on high speed This unit uses an electric element for heating These units cost less to buy but are more expensive to operate than heat pumps Bon Fi bond Fan otor d J F rT drownd m Protector m SE art Bad Fuse Over load L me emet Compressor a 1 Therese bee Hain Switch Figure 190c AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 327 Thermostat With Internal Cwerlesr Protector Fan Capacitor Compressor Bun Capa itor Figure 191a The schematic wiring diagram of a wall or window type air conditioner with an internal overload protector See questions and answers about this diagram on page 349 Before you begin servicing an electrical circuit make certain the electrical supply at the outlet is correct Check the voltage specifications of the unit to be serviced Check the voltage again
364. ners should never be refilled with anything 3 Containers must be protected from objects that could cause cuts or abrasions to the metal surface 4 Don t force connections that do not fit The threads on the regulators or any other equipment must mate with those on the container valve outlet 5 Containers must be stored under a roof and protected from extremes in temperature 6 Do not allow any liquid refrigerant to come into contact with skin as it will cause frostbite 7 SUVA containers must never be used as supports rollers etc Containers must be used only for storage and transportation of SUVA refrigerants 8 Live steam or a direct flame must never be applied to a valve or container 9 Donot attempt to alter or repair containers or valves 10 Containers must never be heated to a temperature exceeding 125 F 52 11 Never tamper with the safety devices in the valves or containers 12 Returnable cylinders must never be refilled without approval from the manufacturers 13 Arope chain or lifting magnet must be used when handling containers crane can be used when a safe platform or cradle is available to hold the container 14 When containers are not in use the valves must be kept tightly closed and valve caps and hoods securely in place SUVA refrigerant blends cause no harm if they are handled in accordance to the manufacturer s safety recommendations Before starting to work make sure there is no dan
365. ng a service valve in the system When the valve is opened the gas in the system can be recovered Never touch liquid refrigerant placed in an open vessel It can create severe injuries when coming in contact with skin Always use leg muscles instead of back muscles to lift heavy objects Be cautious of sharp edges or corners when performing any service on refrigerating units Get into the habit of keeping one hand in a pocket when troubleshooting any equipment with high voltage circuitry Do not forget that even a small shock can be dangerous A reflex reaction to it could cause a fall against a higher voltage source Never drop refrigerant cylinders When transporting two or more be sure that they are blocked or tied so they cannot strike one another Never allow cylinders to be moved with a lifting magnet Always replace the valve protector caps on cylinders after each use Make sure that the test leads on all meters have the proper insulation Never use those with frayed or missing pieces of insulation Always be cautious when vapor refrigerant is released Vaporizing refrigerant causes a severe freeze burn when it comes in contact with skin Also do not touch a valve with bare hands during or immediately after releasing the gas Never touch any uninsulated wire or terminal while the supply power is connected to the unit Make sure the unit is properly grounded In a properly grounded unit should a short occur the electrical char
366. ng a thermometer you can connect a low pressure gauge to the evaporator side of the valve and convert the pressure to temperature If a gauge opening is not available install a shut off valve with a gauge opening If the valve is leaky the evaporator temperature will not rise in which case the valve must be replaced If the valve is stuck shut the warmer evaporator will never cool and the valve must be replaced If the two temperature valve is installed in or near the freezer compartment frost will accumulate on the bellows Remove the valve from the freezer compartment or cover the bellows with a light grease A double temperature valve can be used as a high to low side bypass to assure continuous compressor operation at low loads A low load condition means AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 147 that the evaporator has little cooling to do as the selected temperature has already been attained This type of connection is normally used in commercial applications to limit evaporator temperature See fig 97a A constant pressure valve can also be used to limit the compressor inlet pressure when the system starts after defrosting at which time the suction pressure has greatly increased By installing a constant pressure valve in the suction line the compressor is protected from overload or burnout See fig 97b Figure 57h TEY EE JUS uu lk ers Evaporator a WT alve a I ly cfi TUR
367. ng one take a look at the nameplate on the unit to see what type of refrigerant is used Filter driers are made for different types of refrigerant Whether a flared or a brazed connection is used determine what size tubing it has to be connected to and buy a filter drier for that particular tubing size see figs 76b and 76c Some filter driers are installed on liquid lines and some on suction lines Suction line filters are always installed after a compressor burnout as close the compressor as possible See fig 76a for the brazing technique on a commercial type drier When installing a filter drier on a residential unit be sure to insert the capillary tube about one and a half to two inches into the filter drier entry tube The capillary tube should not touch the element inside the drier but should be in far enough to preclude any possibility of melted solder running in over the end of the capillary tube plugging it Before brazing is begun the filter drier entry tube has to be crimped along one side to form a snug fit around the capillary tube EVACUATING A SYSTEM BY USING A VACUUM PUMP 1 Shutoffthe unit 2 Connect the vacuum pump to the center connection of the gauge manifold and the gauge manifold to the high side and low side of the compressor through piercing or any access valves see fig 84 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 109 3 Run the vacuum pump until you get a vacuum reading of about thirty inche
368. ng valve and the compressor Assume the compressor is OK and there is sufficient refrigerant in the sealed system When the thermostat is set on COOL the compressor starts running but there is no cooling When set on HEAT the compressor starts operating and heating is produced What electrical components are most likely responsible for this and must be checked The reversing valve solenoid or the reversing valve relay 10 11 12 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 349 QUESTIONS AND ANSWERS ABOUT THE DIAGRAM ON PAGE 327 What type of fan is operating in this unit PSC type It is not a shaded pole type because it uses a capacitor How many speeds does this fan have Two Does the compressor use an internal or an external overload protector Internal How is the start winding removed from the compressor circuit There is no starting relay in this type of compressor How can the fan motor be directly tested With an ohmmeter See pages 82 through 85 Does the fan motor cycle off with the compressor No If the fan motor ran on low speed but not on high speed would it be defective No the switch would be defective If the unit normally draws 9 A while running how many amperes will it draw in starting At least three times the running amperes What type of fuse should be used for this unit A 20 A time delay type to tolerate the initial surge that start up draws If power reaches the un
369. ntacts terminals 3 and 4 When the normally open contacts are closed the defrost heater becomes energized only for a short time The normally closed contacts energize the compressor s and the condenser fan s Terminal 1 connects power Figure 54b to the compressor s and the condenser fan s Terminal 4 connects power to the defrost heater Twenty four volt power connected to terminals 5 and 6 energizes the timer motor When normally closed contacts open the normally open contacts close simultaneously and vice versa TESTING A COMMERCIAL TIMER 1 Disconnect the power and wires connected to the timer terminals 2 Check the diagram inside the timer door for normally open NO and normally closed NC contacts such as the ones in figures 53a 54a and 54b Remove the wires connected to the terminals 4 Set ohmmeter scale on X1 and zero it No adjustment is necessary if you are using a digital meter 5 Turn the dial clockwise until it reaches the zone where the distance between the clicks is longer The unit is now in the cooling cycle Touch the probes to the normally closed contacts numbers 1 and 2 The meter should register continuity Otherwise replace the timer po uone40d4J0 2113293 UOBeJed AsaynoD 10 Figure 54k AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 79 Turn the timer dial clockwise to the area in which the distance between the clicks start stop time tabs is shorte
370. nues AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 173 SHORT CYCLING AND A BAD COMPRESSOR Motors draw up to 600 more current at the instant of starting This increased starting current tends to overheat the start winding if the motor cannot reach its operating rpm within 3 seconds to permit the motor run winding to take over If a short or disconnection in the motor run winding occurs the compressor motor will continue running on the start winding and very rapidly overheat causing the overload protector to open the circuit When the overload protector bimetal cools it will close the electrical circuit to the compressor until it senses the high temperatures again and the cycling on overload continues Also a binding or stuck compressor rotor causes too much current draw and consequently cycles on overload SHORT CYCLING AND A BAD OVERLOAD PROTECTOR When an overload protector cracks or gets weak it loses its ability to transmit power long enough for the compressor to reach its initial speed As soon as the overload protector warms it disrupts the power causing the unit to short cycle Under normal conditions a motor compressor operates at 125 F 52 C When the temperature rises to about 225 F the overload protector opens the circuit to de energize the compressor motor When the motor cools to about 160 F the bimetal in the overload protector flexes and closes the circuit to energize the compressor motor again In many co
371. o damage the compressor than one that is undercharged This overcharge of refrigerant is returned to the compressor crankcase as a constant floodback during operation reducing compressor life and the cooling capacity of the unit Charge the unit to the proper level for a capillary tube system charge by the superheat determined on charts available from valve manufacturers For TEV systems without a liquid receiver charge by subcooling the liquid refrigerant to an optimum of 10 F less than condensing temperatures at full load if possible For systems using TEVs and receivers charge by sight glass located at the TEV inlet Charge until the bubbles in the sight glass disappear 2 Oil overcharging should be avoided as this creates the possibility of oil slugs which can damage the compressor and it also hinders the performance of refrigerant in the evaporator If there is excess oil in circulation the evaporation rate of the refrigerant is slowed down because oil acts as an insulator AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 369 Remove the oil and maintain levels according to the manufacturers recommendations 11 2 Oversized Compressor and High Superheat When an oversized compressor is used extra suction power is applied to the system creating a drop in pressure in the evaporator The direct drive motor compressor either runs too fast or it has a wrong size pulley creating lower than normal suction pressures Figu
372. o little water circulated over evaporator plate Evaporator thermostat set on Thin Ice Cubes Evaporator thermostat bulb installed in wrong location Ice Cubes Come Out Too Thick Faulty evaporator thermostat Evaporator thermostat set to produce thick cubes Ice Cubes Have Unpleasant Taste Food stored in ice bin Some packaging material left in unit Water supply has excessive mineral content Ice Slab Won t Relate in Defrost Cycle Mineral deposits built up on evaporator plate Faulty hot gas defrost solenoid valve Faulty ice thickness control Ice thickness control out of adjustment 199 Remedy 8 Clean evaporator plate Recommend that a water softener be installed for the unit to end problems of mineral deposit buildup on plate and in lines and valves Clean condenser Repair or replace condenser fan Check for stuck water float repair readjust or replace as necessary Check water tank Install water softener for unit Replace thermostat Check water pump and lines Clean or repair as necessary Recalibrate thermostat by turning its adjusting screw clockwise to obtain desired thickness Make sure there is a shim between the thermostat feeler tube and evaporator bracket Replace thermostat Turn adjusting screw to obtain desired thickness of cubes Advise customer to remove food Be sure all packing material is removed from unit Refer customer to local water
373. oblem you re ready for the next step Conduct gauge manifold tests Connect a service gauge manifold to the system Observe high side and low side pressures as you perform the following procedures To see if the valve is closing remove voltage to the valve by disconnecting any wire in the circuit With the circuit open low side pressure should begin to drop Wait three or four minutes If pressure does drop the valve is closing freely it is not clogged or sticking 388 To see if the valve is opening remove the thermistor from the circuit by disconnecting the thermistor wires Connect the open wire from the 24 volt source to the open wire from the valve fig 213 This will send 24 volt current directly to the valve and low side pressure should begin to increase If it does the valve is opening properly This type of testing cannot be done with a capillary tube system With a thermostatic expansion valve you will have to remove the thermal bulb and heat it to see if the valve opens properly Replace components if necessary If you find the thermal electric valve or thermistor to be defective replace those components with exact duplicates Replace only the part that has failed it is not necessary to replace any valve or thermistor that is operating properly When replacing the valve mount it with the head up or within 30 of upright if possible This prevents any liquid from migrating to the bimetal chamber where it might a
374. ol water flow into the condenser until the condenser cools and the head pressure drops At this point the pressure exerted on the valve diaphragm is decreased causing the water valve to decrease or shut off the flow of water See picture at upper right For more details refer to page 360 WALK IN CABINETS They are often referred to as walk in coolers and are in wide general use in restaurants supermarkets convenience stores and floral shops Their size varies according to the needs of the business but their height is generally seven feet seven inches up to nine feet ten inches Most units are prefabricated making transportation and setup easier They are usually constructed of galvanized aluminum or stainless steel for the exterior and have metal inside walls and foam for insulation They are sometimes called knockdown boxes For safety they must have door latches that can be opened from the inside Evaporators in these units are usually wall mounted with two three or four fans depending on the size of the unit Condensing units are placed outside or on the roof 214 Some walk in coolers have frozen food compartment with a separate evaporator and condensing unit Many walk in coolers installed in restaurants have reach in compartments with separate doors for frequently used small items This saves time for the food handlers and prevents frequent opening of the main door Most walk in coolers have a temperature range of 35 F to
375. omponents will become inoperative Compressor and condenser fan motor What happens if the transformer becomes inoperative Nothing will work except the crankcase heater What happens if the wall thermostat switch is turned to ON position The indoor fan motor will run all the time LEGEND CR IFR TEI CONT TC2 IFC CH Orci AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 337 A 460 volt three phase 60 hertz unit 460 3 60 Li L2 LJ A TYPICAL SCHEMATIC WIRING DIAGRAM of a central air conditioner operating on a three phase power supply It operates on a 460 VAC 60 hertz circuit The 24 VAC circuit is inside the thermostat Control Relay Internal Fan Relay Thermostat Contact Cooling Stage 1 Internal Fan Operating Continuously Thermostat Contact Cooling Stage 2 Internal Fan Coil Crankcase Heater Outside Condenser Fan 1 IFM Internal Fan Motor OFC2 Outside Condenser Fan 2 FCPS Fan Control Pressure Switch LLS Liquid Line Solenoid HPS High Pressure Switch Control DLT Time Delayed Thermostat LPS Low Pressure Switch Control FU1 through FU4 Fuse 1 fuse 4 338 EXPLANATION OF THE DIAGRAM ON PAGE 337 The commercial central air conditioner represented by the schematic wiring diagram on page 337 operates on 460 VAC There are two condenser fan motors OFM1 and OFM 2 for more efficient heat exchange cooling On the right hand side of
376. on Find the lines that supply power to the compressor Normally one goes into the overload protector and one to the start relay Connect these lines to the remaining two wires on the hard start kit Plug the unit back in to the power source and if the compressor starts and continues to run then the problem is solved If it does not the compressor is defective In which case remove the new hard start device and replace the compressor Hard Start f TO THE COMPRESSOR Also see fig 47a CONNECTING A HARD START KIT 64 HOW UNCLOG A CAPILLARY TUBE Sometimes a wax buildup or dirt obstructs the passage of refrigerant through a capillary tube Due to its length the capillary tube may run through places difficult to reach In such cases it is easier to unclog it rather than replacing it A capillary tube cleaner can be purchased from most major refrigeration supply houses The way the device works is that it forces wax and dirt out of the capillary tube under high pressure Some of these devices are capable of producing pressures as high as 3 000 psi An obvious sign of a clogged capillary tube is that the back pressure reads lower than normal or even vacuum the head pressure reads higher than normal the unit no longer cools while running constantly and the condenser feels cooler than normal To use a capillary tube cleaner disconnect the capillary tube at both ends Flux and apply heat to the brazed joint to re
377. on To eliminate base fan cycling on ambient air temperature Use variable speed fans or flooded type head pressure control system but not both together CAUSES OF SUCTION PRESSURE PROBLEMS IV 1 High Suction Pressure High Superheat Evaporator Outlet Probable Cause Unbalanced system load in excess of design conditions Compressor discharge valve leaking Leaking hot gas defrost solenoid hot gas bypass valve Hot gas bypass regulator piped direct to suction without a liquid injection TEV Remedy Balance system components for the appropriate load requirements if necessary Check valve per page 47 Replace valve if necessary Check and replace hot gas bypass valves if required Install properly sized liquid injection thermo valve IV 2 High Suction Pressure Low Superheat Evaporator Outlet Probable Cause Oversized expansion valve Pin and seat of expansion valve drawn eroded or held open by foreign material resulting in liquid floodback Ruptured diaphragm in an AEV resulting in liquid floodback External equalizer line plugged or equalizer connection capped without providing a new valve body with an internal equalizer Moisture freezing valve in open position Leaking valve stem packing Valve superheat setting too low Leaking liquid line in suction heat exchanger Unit coming out of defrost Remedy Replace with correct size expansion valve Replace valve Install filter drier to rem
378. on rate By employing this principle bimetal switches can Courtesy of Wagner Products Corporation open and close circuits through heat sensitivity Miami Florida 88 A QUICK TERMINATION THERMOSTAT CHECK USING THE BYPASS METHOD 1 Disconnect the power to the unit 2 Disconnect the termination thermostat from the unit 3 Take the two disconnected wires leading into the termination thermostat and connect them together making sure this new bypass connection is well insulated 4 Turn on the unit and turn the timer screw to put the unit into the defrost cycle If the defrost heaters begin heating in this bypassed circuit the termination thermostat is bad and it must be replaced COMPRESSOR NAME PLATE ETEL Of CFE ACE LETTER H INDICETES HITTI EET 2 16 THDTcM OF BUNTE FOLL MIR 2 iG THDICATE SGEVTRIGAL SATIS Fig 64a A typical name plate for a Tecumseh compressor Fig 64b Name plate for a commercial console refrigerator on the top and name plate for a Trane central air conditioner condensing unit The months are identified alphabetically A January B February etc with the letter i omitted OD sjonpoJg uesuun29 Jo Asano Figure 64a LEA TILL wo PTI mh im B m 11 0 m 235 WI ee r p Bi 2i A ee 5 m a m BS 11
379. ondenser in a water cooler pp 205 204 29 How is water temperature affected in a water cooler by a faulty start capacitor p 205 30 What can be wrong if the filter drier is hot to the touch p 208 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 223 What can be wrong if the low pressure line from the evaporator feels considerably colder than normal p 208 In what position should the suction line access valve stem be when the system is being charged p 155 In how many locations are access valves usually installed p 155 Where are oil separators installed in a sealed system p 154 How does a solenoid valve operate pp 148 and 149 Where are check valves installed in the sealed system p 144 and fig 96 How is a low pressure control checked p 142 Explain how to determine the cut in and cut out setting on a low pressure control pp 141 142 140 What is the purpose of the two screws on top of the low pressure control p 141 How many types of pressure controls are there p 139 How many functions do sight glasses perform p 139 Explain the difference between R 12 and R 22 refrigerants p 137 What refrigerant is used as a flushing agent p 137 What could cause frost on the expansion valve while unit runs on vacuum pp 220 221 What is the head pressure in a commerc
380. onto the output shaft of transmission number 1 Place lower bearing number 3 into housing number 4 See installation lower bearing and housing Place housing on transmission and secure with bolts number 5 Place gasket on top of bearing Locate ceramic seal number 7 on top of housing Install shaft seal number 8 onto bottom journal of the auger number 9 For proper replacement see Shaft Seal Replacement in figure 131f Carefully set the auger and seal assembly down onto the ceramic seal and lower housing and load seal Slide evaporator assembly number 10 down over auger and housing Use P 80 or water on the O ring that is around the ceramic seal Secure evaporator to housing with bolts number 1 Check threaded holes in the extruding head Make sure they are clean and moisture free Place extruding head down into the evaporator tube Treat extruding head bolts with Grade AA Loctite Loctite is a gluelike substance that is used on bolt and screw threads when a lock washer is impractical or unsightly It can be broken loose by a firm blow to the screw or bolt head It is usually available at most hardware and sporting goods stores Make sure threads are clean and moisture free NOTE Loctite set up time is half an hour Do not run ice maker until Loctite has time to set up Hold down on the auger and screw bolts into the extruding head through the neck of the hopper Hand tighten Tighten extruding head bolts
381. ood compartments too warm cont Freezer compartment too cold Frequent accumulation of ice on evaporator Refrigerator compartment too warm Linted or poor air circulation around condenser Poor air circulation around unit Accumulation of ice on evaporator Refrigerant shortage Leaky door seal Door opened excessively Thermostat set too cold Defective thermostat Thermostat sensor not clamped tightly to evaporator Defrost drain plugged Leaky door gasket Defective defrost heater Defective defrost bimetal Defective evaporator fan Compartment light stays on Poor air circulation due to overloading of shelves Hot food in refrigerator Thermostat set too warm Leaky door seal Clean condenser and check condenser fan and replace if necessary Provide sufficient clearances for proper air circulation A bad thermostat timer or defrost heater could cause the problem Check each and replace as necessary Check low side pressure If too low check for leak Repair evacuate system and recharge it Adjust door or replace seal as necessary Advise customer to minimize frequency of door openings Adjust thermostat Check and replace if necessary Tighten clamp Inspect and clean drain line Check and replace if brittle cracked or worn Check and adjust door if needed Check and replace if necessary Check and replace if necessary Check fan an
382. opper tubing up to three eighth inch in diameter Figure 45g shows a typical pinch off tool To use it put the tubing through the opening to the point where it is to be sealed As the shaft is turned by the T handle the tubing is compressed between a ball bearing at the end of the shaft and the die at the base of the tool Apermanently pinched line is made by turning the handle slowly and not overtightening PA Ug SALA TROL A a This too becomes necessary when there is a need to test the compressor efficiency or in an emergency such as a severe leak when a section of the sealed system must be isolated for repair For example in commercial units where there are multiple evaporators the one with a leak can be isolated while allowing the rest of the system to operate during the repair work Thus the contents of the unit can stay cold and be saved 68 ADDING OIL TO THE COMPRESSOR Systems with hermetic compressors seldom requires charging with oil When a leak occurs oil escapes with the refrigerant and must be replaced for proper lubrication Loud compressor noises can sometimes be remedied by adding a small amount of oil usually no more than one half cup to the hermetic system Use oil compatible with the system and of proper viscosity 1 Install two access valves on the refrigerator one on the suction line and one on the liquid line see figs 45f 45k 21 79 2 Connectthe manifold gaugesto the valves
383. or discharge line to circulate directly through the evaporator coil bypassing the condenser and the refrigerant control to loosen the ice See figs 16 and 16a Other ice machines operate by circulating water over a cold evaporator plate or over the molds by flowing through a perforated tube In the harvest cycle of these smaller and mostly residential units a solid slab of ice falls onto a heated grid and thereby cut into cubes and the cubes then fall into the storage bin Some ice machines produce flakes see fig 130 In this type of ice machine water flows over a freezing cylinder evaporator with sharp spiraling cutting blades called an auger When a thin layer of ice is formed the low temperature is detected by a sensor causing a switch to close the circuit to a motor which turns the cylinder causing the ice to be shaved into flakes and expelled into the storage bin see fig 130 Storage bins employ either of the following two methods to control the amount of ice accumulated 1 Mechanical a lever operated control This is an arm projecting into the bin When the level of ice rises enough to lift the lever the power to the unit is cut off by a switch connected to the arm until some of the ice is removed 2 Thermostatic a sensing bulb is installed near the top of the bin When the ice level in the bin reachesthe bulb the contraction of the refrigerant within the bulb transmits pressure changes to the thermostat causing
384. or each person who occupies the building depending on his or her activity Naturally if a person just sits or sleeps the body gives off less Btu than if engaged ina physical exercise A rule of thumb for determining the required tonnage for a new unit is to find the difference between the average outside temperature and the desired temperature inside the air conditioned area multiplied by the square footage of the building plus all the extras mentioned above multiplied by 3 4 to equal the total required Btu The total required Btu are then divided by 12 000 to determine the required tonnage the size of the unit required Average outdoor temperature F indoor desired temperature F Btu generated by the occupants equipment wattage W x 3 4 total required Btu Then total required Btu by twelve thousand required tons EXAMPLE Determine the air conditioner tonnage required for a thirty by forty feet hair salon where the average summer temperature is 95 F with a desired conditioned temperature of 75 F The salon has five customer seats five technicians five hair driers at 700 watts each and five 100 watt light bulbs SOLUTION 95 F Average outside temperature 75 F inside 20 F temperature difference 30 x40 1200 ft 1200 f x20 F 24000 Btu 5 hair driers x 700 watts 3500 watts x3 4 11900 Btu 5x100 watt light bulbs 500 watts x3 4 1700 Btu 10 people x500 Btu 5000 Btu TOTAL 42 600 Btu AIR
385. or is probably made of aluminum Advise the owner to immediately unplug the unit to prevent any further damage to the compressor due to moisture penetrating the system If the unit continues to run the compressor will be ruined in no time Any repair of an aluminum evaporator is made with an epoxy instead of brazing The high temperatures produced by brazing cannot be used on aluminum that has a low melting point Aluminum repair kits are available at regular supply houses They contain a tube of resin a tube of hardener a vial of cleaner acetone emery cloth mixing spatulas popsicle sticks and a piece of aluminum foil patching These kits contain easy to follow instructions but most important of all is the absolute thorough cleaning of the surface prior to applying the epoxy It cannot be stressed too much how important it is to use the acetone to thoroughly clean the area to be repaired Any trace of dirt oil or residue does not allow the repair substance to adhere Any time the sealed system is opened the filter drier must be replaced with a new one When a large leak is found in copper tubing it is sometimes easier to cut the tubing and reconnect it by flaring or silver brazing Prior to silver brazing use a short length of copper tubing with an inside diameter equal to the outside diameter of the tube being repaired to join the two ends This makes an excellent silver brazed joint Square off the ends to be joined and 124
386. or pressure minimum evaporator pressure flooded evaporator in low side float system flooded condenser in high side float system see figs 114 and 115 The electric valve can make system analysis and system troubleshooting fast and easy Service personnel need only attach a voltmeter to the electric valve The readings obtained from the voltmeter will tell how the valve is operating at a glance A single check of system conditions will x indicate valve reaction x identify problems elsewhere in the system Complete servicing details are given under the thermal electric valve troubleshooting guide in the Refrigeration Fluid Flow Controls and System Troubleshooting AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 167 AUTOMATIC EXPANSION VALVES These are also referred to as constant pressure or pressure reducer valves see fig 108 Because of their versatility these valves are produced in a variety of types and sizes and can be installed in different parts of the sealed system then adjusted to the pressures desired They can be used as high to low side bypass regulators evaporator pressure regulators compressor overload protection evaporator freeze up protection and also as an expansion valve for one fourth to three ton capacity room air conditioners ice cream units ice makers water coolers dehumidifiers and central air conditioners LO gu ge a pas eee Leela po ere Thes
387. or wires t t match the old thi new motor must match the old one this Before testing the condenser fan information is on back of motor motor make sure that the failure is Figure 56c not due to lack of power reaching the fan motor Checking Procedure a Connectatestlamp equipped with alligator clips see page 21 to the two wires removed from the fan motor Be sure the clips are well insulated and are touching no other part of the unit b Reconnect the power to the unit If the lamp glows the fan motor will have to be replaced Occasionally even a bad motor starts and runs for a while and then stops This is due to an internal electrical short which is evidenced by an overheated fan motor after a few minutes of running it feels too hot to the touch or due to worn shaft bearings In either case replace the fan motor Sometimes the fan motor shaft jams and becomes hard to turn The shaft should turn freely without squeaking when rotated by hand if not replace the fan motor CHECKING FAN MOTORS WITH AN OHMMETER Disconnect the power supply Disconnect the fan motor wires from the unit Set the ohmmeter to the RX1 scale and zero it Connect each probe to a fan motor terminal The meter should register a continuity reading If not the motor is defective and must be replaced gt wu AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 83 In the case of capacitor run or capacitor run capacitor start fan motors
388. orator Check for leaky door gasket replace if necessary Check for defective defrost heater on the evaporator coils Check for bad defrost timer Replace these as necessary If it s a normal defrost unit needs defrosting Check for leak repair and recharge Check and replace if necessary Check and replace if necessary Check and replace if necessary Check outlet for proper voltage 107 126 Unit may require separate or new circuit New line must be installed by licensed electrician Check and replace if necessary Replace cord with one of proper size Discharge and evacuate the system Install new filter drier and recharge the system Turn knob to warmer setting Check and replace if necessary Check and replace if necessary Remove object obstructing control Check capillary tube and clear obstruction or replace tube Check and replace if necessary Check for continuity replace if necessary Check and replace if necessary AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 121 PROBLEM POSSIBLE CAUSE REMEDY Unit makes noise when operating Freezer door freezes shut Unit runs continuously but does not cool Compressor no longer runs Accumulation of water at bottom of unit liner Nothing works except the cabinet light Ice built up on bottom of freezer freezer liner Sweating inside the cabinet Flooring loose or unstable Loose compres
389. orator temperatures and consequently higher temperatures in the cabinet b higher operating temperatures in compressors and condensers c longer running time and d slow ice production and poor refrigeration This is usually misdiagnosed as a low charge or bad compressor due to the overheated compressor short cycling on overload Figure 122 SIGNS OF LOSS OF REFRIGERANT Low side pressure reads lower than normal High side pressure reads lower than normal Low amperage reading Read the amperage the compressor draws Do it by placing the ammeter around the wire to the compressor run or common terminal See fig 124 The nameplate on the unit will indicate the correct amperage the unit should draw while running shown as FLA as opposed to the amperage it draws at the instant of starting shown as LRA on the nameplate or in the reference book mentioned on page 105 4 Little or no frost on the evaporator coil 5 Unit runs continuously nonstop 6 Unit starts immediately after it is turned off Instead of the usual two to three minute delay for the head and back pressures to equalize through the capillary tube during the off cycle 7 In cycle defrost units the temperature in the ice compartment drops below normal while the temperature in the fresh food compartment rises above normal because an insufficient amount of vaporizing refrigerant circulating through the evaporator becomes superheated by the time it reaches the last pas
390. ording to the formula 120 V per 1000 or 0 120 120 1000 A would flow through the body more than enough for a lethal dose AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 297 However if the unit is adequately grounded the current is bled harmlessly to ground with hardly a tingle felt Remember with 120 volts it only takes as little as 0 025 A 25 1000 to cause death Connecting the chassis to a cold water pipe with a length of wire is an excellent ground for the unit The reason a cold water pipe is used instead of a hot water pipe is that hot water pipes are usually installed inside the structure whereas the cold water pipe runs directly into the ground where it is connected to the main water line USING THE OHMMETER CAUTION The ohmmeter is to be used only on circuits with no current Be sure the equipment is unplugged before using an ohmmeter as current flow through an ohmmeter will destroy it Any component to be tested must first be isolated from the rest of the circuit by removing any wiring connected to it Several examples of the use of the ohmmeter and voltmeter have already been given in this book The best diagnostic instrument is a combination voltmeter ammeter ohmmeter which is referred to as a multimeter see pp 303 and 305 All of the functions are indispensable to a refrigeration and air conditioning technician Before setting the multimeter to check the ohm rating of a component disconnect the power
391. ors should be manually defrosted two to four times a year In cycle defrost units the temperature ranges between 0 F and 10 F in the freezer compartment and 38 F to 45 F in the fresh food compartment The normal low side pressure ranges between five and ten pounds per square inch 5 10 psi AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 19 FROST FREE REFRIGERATORS AND FREEZERS In these units the evaporator coil is automatically defrosted in regular intervals every day A fan is mounted on the evaporator to draw air from one side move it over the evaporator coil and force it into the freezer and fresh food compartments through a damper see figs 6 8 and 9 A thermostat controls the operation of the compressor to maintain food at desired temperatures It is regulated by a manually adjustable knob A baffle control knob inside the cabinet of the unit manually controls the temperature of the fresh food compartment by increasing or reducing the flow of cold air into that compartment There are two defrosting systems used in residential frost free refrigerators and freezers 1 Electric heater system 2 Hot refrigerant vapor system hot gas system Electric defrost system A timer see figs 7 and 11a 11e automatically de energizes the compressor and the evaporator fan motor and at the same time it energizes the evaporator defrost heater every six eight or twelve hours depending on the type of timer being used to de ice the
392. ort cycle pp 119 120 What are the symptoms of a leaky door seal p 118 Why is it a good habit to check the sealed system with a leak detector after a repair p 116 How isthe correct amount of refrigerant metered into large commercial units p 113 When is liquid leak detector usually used p 116 Why is it necessary to use a charging cylinder p 111 Why is a refrigerant tank turned upside down when filling a charging cylinder p 112 What three steps should always be taken before charging a system when a sealed system is opened for any reason p 108 What method is generally used to charge a commercial refrigeration unit p 115 ADDITIONAL CONTROLS FOR COMMERCIAL UNITS AND COMPRESSOR SERVICE VALVES This section covers the controls used in commercial and residential units It includes the temperature pressure relationship common types of refrigerant temperature and pressure controls their operation and placement in sealed systems Solenoid Boisture Head Liquid tine aire q a Liquid Pressure Control Filter Drier w Tudipabor p g m SS Sar z Stabilizer E Suction Line Evaporator Pressure Filter Drier Regulator Courtesy of AUDO Contos 131 132 SATURATED VAPOR REFRIGERANT PRESSURE AND TEMPERATURE RELATIONSHIP There are several types of refrigerant with different qualities and boiling points These different boiling points affect pressures in the evaporator and the cond
393. ot be more than 10 above motor rating OTHER PROBLEMS Unit Runs Too Long Dirty coil heavily frosted coil Inefficient compressor Low refrigerant charge Air or moisture in system Evaporator coil too small Tubing too small or restricted Pressure temperature control contacts struck closed Expansion valve too small Expansion valve open too far 10 Ambient air too warm Unit Short Cycles Low on refrigerant Overload protector cuts out System overcharged Cut in cut out differential set too close Clean condenser or de ice evaporator Replace hermetic type have others repaired Repair leaks add correct charge Purge system replace filter drier and recharge Replace with larger coil compatible with compressor horsepower Replace with larger tubing remove Check replace control if necessary Replace with larger valve Reset valve Turn stem clockwise Provide better cooling or move condenser to cooler location Add proper type and amount of Freon Look for linted condenser slowed water cooling pressure too high or inefficient compressor Release Freon may be necessary to purge system Increase differential AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY Problem and Possible Cause Unit with water cooled condenser cycleson 5 high pressure cut out Leaky valve on discharge line Leaky expansion valve Suction Line Has Condensation or Frost 1 Expansion valve op
394. ot compressed rmfrigeramt is forced Figure 1 out of Lime zapret o Sigh Fresaure BmsErigezant COL e Bigh Pressure Liquid Bafrigerg amp st Low Pressure BHafriqerant Cempraessos s cblon peer raes in cool vapor refrigeract Low Freaeuce Ligeid Refrigerant AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 9 The liquid refrigerant is then circulated through the filter drier and capillary tube on its route to the evaporator coil connected to the suction side of the compressor A TYPICAL MANUAL DEFROST REFRIGERATOR A Discharge Line B Suction Line Cand D Oil Cooling Lines A heat exchanger is the portion of the warm capillary tube and i i the cold suction Two illustrations of a typical line touching M manual defrost refrigerator Note each other the location of the accumulator or sometimes 3 Its function is to prevent liquid welded together refrigerant from flowing into the motor compressor that can cause knocking and damage Liquid refrigerant is trapped in the accumulator and allowed time to vaporize before it reaches the compressor The direction of refrigerant flow is indicated by the arrows The capillary tube and suction line are placed together and bound with an insulating Figure 2 sometimes encased ina plastic sleeve or just taped together material creating heat exchanger to increase the ef
395. ottom A clogged filter drier or capillary tube can be indicated by a cool condenser because of a liquid buildup in the condenser Filter drier It should feel warm about 12 F or 15 F above room temperature A very warm Weer or hot filter drier can indicate poor air movement through the condenser coil or too much load on the evaporator such as too much warm food to be cooled etc A restriction in the sealed system is indicated by a cool or cold filter drier bid oco RUMHING COWDITIGR Capillary tube It should feel about room temperature coming from the filter drier and cool upon entering the evaporator A cold or frosted capillary tube is an indication of a restriction 208 REFRIGERATED DISPLAY CASES AND WALK IN COOLERS TLilmisated Sign Panal Bel Cinmimg Door mil sarum iu inaubatLon E M axb3um halves i zccmmaridesl Tamparmbures NAI Cabinet Tumpaermiurm paese IFE mSiustabim by Apr Stata of T amirol j xmarvahlm Grilis nn 4 amp Full aut cusdeumina Pans laam unit bahisd grille Eva jet tur pie tiom enllecks in pan behind tha grilis to sgvmpcralw Abe A typical romam netrigeraied dripiag rue Thee ioe With higad oe plas Sons The evapo m maannimi iidr on Sip Bark wall a ihe inp oF h ndr Reg Duos beer odes TR g earn vnm be fro dul erg grille in the bark Thep la d po
396. ouch When it gets stuck in the cooling cycle temperature in the freezer and fresh food compartments goes abnormally high as the compressor runs continuously causing a thick layer of ice to form on the evaporator coil Timer terminals rarely get fused TEMPERATURE CONTROL together This causes the defrost heater to remain on while in the cooling cycle When this happens the compressor runs continuously and the unit no longer cools In this case the timer A Knob Mount B Electrical Terminals must be replaced Bui Thermostat Temperature Control or Cold Control device for automatically regulating the temperature inside a refrigeration unit by controlling the operation of the compressor The manually adjustable control knob attached to its operating mechanism is mounted inside the cabinet usually with two screws It consists of a gas charged capillary tube called a sensing bulb connected to the operating mechanism The sensing bulb is attached to the evaporator The operating mechanism of the thermostat responds to the pressures exerted from the trapped gas within the sensing bulb As the temperature of the evaporator coil drops the volume of gas decreases due to contraction and thus the amount of pressure exerted upon the accordion type bellows within the thermostat operating mechanism is reduced causing the bellows to contract and open a set of contacts disrupting the flow of current to the compressor motor With t
397. outside coil and it should be defrosted often enough to maintain the optimum performance of the unit When the unit is taken to the defrost mode the reversing valve is de energized and the direction of the refrigerant flow is reversed with the compressor running During this time electrical heating elements are energized to supplement the heat to the air conditioned area Every time the unit is shifted to the defrost cycle a surge of liquid refrigerant is forced back to the compressor this is called flood back An accumulator is installed on the suction line to compensate for this flood back In fact the accumulator acts as a receiver to store excess refrigerant so that it gets a chance to vaporize before going into the compressor Solid state timers boards are widely used to take heat pumps to the defrost mode see fig 176 In these defrost timers a thermistor senses the difference in air temperature entering the evaporator coil and leaving it When the thermistor senses a temperature difference of about 25 F the solid state board takes the unit into the defrost cycle Unlike mechanical timers that put a unit into the defrost mode every so many hours solid state defrost systems put the unit into the defrost mode only when needed but as often as necessary The defrost boards are equipped with testing posts through which the board can be easily tested for proper operation The testing procedure comes with most new boards H
398. ove foreign material from system Replace valve sensing assembly If equalizer is plugged repair or replace Otherwise replace with a valve having the correct equalizer Apply heat gun to valve to melt ice and install a new filter drier to ensure a moisture free system Replace TEV Increase superheat setting turn valve stem clockwise Liquid to suction heat exchanger defective May not be needed review requirements Normal Let the system balance See section 1 14 on measuring and adjusting superheat 378 IV 3 Low Suction Pressure High Superheat Evaporator Outlet The probable cause is a starving evaporator See section on high superheat IV 4 Low Suction Pressure Low Superheat Probable Cause a Light load condition Poor distribution through evaporator causing liquid to short circuit through favored passes At full load there should be no more than 5 F difference in superheat between any two circuits as they enter the header Compressor oversized evaporator undersized Uneven or inadequate evaporator loading due to poor air distribution Dirty evaporator filters Coil icing Frozen or slushed chiller Low water flow through chiller Excessive accumulation of oil in evaporator IV 5 Fluctuating Suction Pressure Probable Cause Incorrect superheat adjustment Improper remote bulb location or installation Floodback of liquid refrigerant caused by poorly designed liquid distribution d
399. ove them Styrofoam is used as insulating material in most water fountains A heat exchanger is used to precool the water by using the chilled waste water Temperature of the drinking water should generally be around 50 F Businesses employing large numbers of people use water cooling units with several dispensers bubblers and one large condensing unit The smaller type office water coolers with bubblers for dispensing hot water as well as cold have a hot water storage tank and separate electrical heating units with thermostats to control the temperature Water supply connection Electrical and plumbing service must enter cabinet within this area 3 Water inlet connection 4 Heating tank drain connection on hot and cold models 5 Tailpiece 6 Waste water connection MI 8 Figure 132 Cooling tank drain connection Hot and cold models only B A N ie m 1 Bigbi Glow MW Axvmmm P om Filter oriar Lote o Qi ae TT An illustration of a typical water cooler that might be used in schools offices or small manufacturing plants In most models water enters a cold water reservoir and when cooled enough a thermostat or low pressure control turns off the compressor until the water temperature in the reservoir rises Some models are designed for use with bottled water instead of city
400. ovide a lower cost retrofit of equipment now using R 502 SUVA HP refrigerant blends are carried in 15 Ib and 30 Ib disposable cans 123 Ib or 1682 Ib cylinders 5000 gal truck tank and 170 000 Ib rail containers Disposable cans used for stationary refrigeration applications are furnished with the same outlet fittings as R 502 cylinders A 123 Ib SUVA HP nonrefillable cylinder comes with a liquid vapor two way valve for dispensing refrigerant either as a liquid or vapor without inverting it On the side of the valve a liquid handwheel is connected to a dip tube reaching to the bottom of the cylinder A vapor wheel is placed on top of the valve Both wheels are distinctly marked for liquid or vapor SUVA HP refrigerants become combustible if they are permitted to come in contact with high concentrations of air above atmospheric pressure Never leak test equipment with a pressurized mixture of air and SUVA HP refrigerants When filling refrigerant tanks make sure they are not pressurized over one and a half times above the normal SUVA HP refrigerant operating pressure Relief valves on either the refrigerant supply system or the tanks must be set below this point PREPARATION FOR CHARGING AND FILLING x Refrigeration units or cylinders must never be under positive air pressure Normally they should be evacuated before charging begins Remaining refrigerant should be removed from refrigeration units or cylinders before evacuation beg
401. own at the lower left has no scale and the bend must be A BENDING LEVER judged by eye or separate measurement Courtesy of Robinair Division SPX Corporation 9 w 14 15 16 17 18 19 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 45 TEST YOUR KNOWLEDGE ON CONNECTING TUBING What method is used to bend larger diameter tubing fig 27a Generally how many half turns of the spinner should be sufficient to form a flare p 42 Name 4 different types of flare unions fig 24a What are the most commonly practiced ways of joining tubing p 38 How should the torch be positioned while silver brazing p 38 fig 21 When applying heat to a joint how is it determined when to apply the silver solder p 38 What steps should be taken after a joint is silver brazed p 38 39 When should flux be applied to the joint p 38 At what temperature does silver alloy melt p 38 How is refrigeration tubing normally cut p 41 figs 17 18 What kind of coupling is used to braze tubes of the same diameter fig 24 How and why should a silver brazed joint be cleaned p 38 What is the general rule to determine the overlap length when swaging copper tubing p 39 Whatisthe purpose of punches with different sized diameters p 39 fig 23 How is tubing bent with a spring type bender p 44 fig 27 What should be done before applying heat to the tubing p 38 What is used whe
402. pair kit bought from a local auto parts store or a boat dealer When the repair dries it can then be sanded and painted to match the rest of the interior For exterior repair of chipped or scratched paint touch up kits are sold by the dealers for any particular brand The year of manufacture and the color of the unit are needed After applying the touch up paint it may take a day or two for the color to dry to the original shade 102 You may place 150 watt flood light inside the cabinet aimed at one area of the door gasket Close the door and inspect that area A poorly fitted gasket is indicated by light penetration between the door jamb and gasket Inspect the entire gasket by directing the light at consecutive areas of the gasket TESTING THE POWER CORD Disconnect the power cord from the wall outlet and inspect it It should be solid supple and free of cracks splits drying or exposed inner wires or insulation Especially in the case of older units even if the cord is only dry and stiff replacing it is strongly recommended In addition to making the circuit safer it is inexpensive and will save the customer problems in the future If there is power at the wall outlet but none is getting to the unit the power cord must be bad CHECKING PROCEDURE 1 After removing the cord from the wall socket remove the lower access cover in the rear of the unit and disconnect the cord from the junction box k AT
403. pcontet iih bes 15 A pug lume one 175 mfi Hut wih sciam rain lor uek bring tested aed thee mudaie Cize LJ DAL Pure 8 E lee petals JANA rer Depa uin Bor connecte 5 ore E One m conor US end farmin eee Hure ra connect a dum oe TESTING COMPRESSORS WITH A TEST CORD 1 Disconnect the power supply 2 Remove the compartment cover compressor terminal cover start relay and the wire connecting the overload protector to the common terminal 3 Connect the appropriate test cord wires to the proper compressor terminals The three test wires are marked C S and R 4 Plug the test cord into a proper power supply and depress the switch for no longer than three seconds If the compressor never starts or if it stops when the switch is released it must be replaced A good compressor will continue to run because the power is still connected to its run and common windings through the test cord Poor connections also cause compressor failure Be sure to check these too prior to replacing a compressor Tight and clean connections are essential for good current flow If a compressor must be replaced all the data for a duplicate p it com to torva replacement can be copied from the compressor nameplate to ensure getting the right one Do not remove the nameplate The compressor may still be under warranty if it is removing the namep
404. pe of fluid so that the materials of construction will be compatible with that fluid Steel or ferrous metals and aluminum are used in solenoid valves for ammonia service Special seat materials and synthetics may be used for high temperature or ultra low temperature service Special materials are required for corrosive fluids Special attention to electrical characteristics is also important Required voltage and hertz must be specified to ensure proper selection Valves for DC service often have different internal construction than valves for AC applications so it is important to study the manufacturer s brochure carefully Solenoid valves having a spring loaded plunger or diaphragm may be installed and operated in any position however the older style conventional solenoid valve with a plunger which depends on gravity to close must always be installed with the plunger in an upright vertical position with the pipe horizontal An adequate strainer or filter drier should be installed ahead of each solenoid valve to keep scale pipe dope solder and other foreign matter out of the valve When installing a solenoid valve be sure the arrow on the valve body points in the direction of refrigerant flow When brazing solder type connections do not use a torch that is too hot and point the flame away from the valve Allow the valve body to cool before replacing the valve inner parts to ensure that the seat material and gaskets are not damaged by t
405. peretor acero ARR the compressor flowing through a three way valve Dro KHEN d a hold back val Defrast Bolmnoid and a hold back valve SE 1 Magy Belemsid Bafriqasratios j Pan Hidlar Wormally Cloned Solid rats Holat Bafsky Bpcaiver Uer iiv Control _ Tief bed Lor Heaut formally Figure 186a a Cook ng Eppen Check Yale Unit in Cooling Cycle higaid Lim Soleeoid Valve Figure 186a displays amomentary position of the termination thermostat on warm position in the beginning of each refrigeration cycle Timer release solenoid is energized and timer defrost contact is released Due to low evaporator temperature termination thermostat is moved to cold position and current flows through the evaporator fan and the refrigeration cycle continues Figure 186b shows the direction of refrigerant flow in the refrigeration cycle Compressor forces out hot vapor to the condenser It is then forced to flow through a receiver Le Dinde mar valra baii idi Tiira rmp liae Eimi i smi i 1 Lis Greg Figure 186 une mane 318 A typical two pipe hot gas defrost system Figure 186c Fans Ref roat pali state nal Falaty feral ver
406. placed In household refrigeration units they are installed under the compressor terminal cover and connected to the compressor start and run terminals Some relays come with three openings that connect the starting relay to the three terminals of the compressor Many GE units are of this type See figs 46 and 46a Figure 13 Overload protector This is ir COMPRESSOR overheat overload protection TERMIHAL oae for the compressor in the hg form of a bimetal reusable i safety fuse If for any reason the temperature of the compressor motor goes too high the bimetal strip within AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 27 the overload protector will shut off the power to the compressor until it cools sufficiently for safe operation It is installed under the compressor terminal cover See figs 12 and 55 Under this cover there are three compressor terminals a run winding terminal marked R a start winding terminal marked S and common HERMETIC terminal marked C The overload COMPRESSOR KJ CN protector is connected in series vom with the common terminal of the 2 Discharge line compressor 3 Suction line seuisnpu JPEN Jo sa34no5 pue u1JoN UOLS Compressor The compressor is the heart of the refrigeration unit It is a motor operated device that circulates refrigerant much as a pump would in a sealed system All household and many commercial ref
407. porates instantly flashes and turns into vapor as it passes through the orifice of a refrigerant control float valve A valve to control the level of liquid in a container operated by a device floating on the surface of the liquid floodback The migration of liquid refrigerant into a part of a system during the off cycle flooding Permitting liquid refrigerant to flow into certain parts of the refrigerating system flooded system Refrigerating units employing a high or low side float system Uncommon in modern refrigeration flux The chemical contained in some solders or applied separately to surfaces prior to brazing to prevent oxidation Electrical A circular magnetic field created around a conductor carrying a current four way valve Also referred to as a reversing valve A device used to reverse the flow of refrigerant between the evaporator and the condenser without passing through the compressor freezing point The temperature at which a liquid solidifies Freon See refrigerant frost free refrigerator A refrigerator using a defrost timer fuse A protective device in an electrical circuit A conductor with less electrical tolerance than other elements in the circuit An overload or electrical surge causes it to melt and open the circuit gas The state of a substance which is neither solid nor liquid 424 gasket Rubber or other pliable material placed around the inner edge of a refrigerator door to seal the
408. porator heats the ice cubes loosen and fall into the ice bin The cycle is repeated until the level in the bin goes high enough to touch the sensing bulb The low temperatures are then transmitted to the thermostat operating mechanism causing a set of contacts to open disrupting the flow of power to the unit At this point the ice making operation is stopped until some of the ice is removed from the bin 188 129 Also see Figs 16 and 16a Figure 129 illustrates how hot gas from the compressor is bypassed to circulate through a coil adjacent to the machine evaporator to loosen the ice at the beginning of every harvest cycle When a hot gas bypass system is used in ice machines the ice thickness thermostat controls the solenoid valve Figure 16 illustrates a different method of bypassing hot gas to serve the same purpose HARVEST CYCLE gt amp ICE PRODUCTION CYCLE Compressor Defrost solenoid valve Capillary tube Evaporator Defrost Hot Gas Bypass Filter Drier Accumulator HOT GAS DEFROST SYSTEM When the solenoid valve is energized by a timer it opens allowing some of the hot gas to circulate though the tubing On the way back tothe suction side hot gas is circulated through a capillary size section oftubing to become partially cooled before entering the compressor When the frost is melted the defrost bimetal which is wired in series with the solenoid valve cuts o
409. pped with an external overload protector check that too However if low voltage is suspected check the circuit breaker or fuse box If the compressor feels cool to the touch and does not operate check the circuit breaker for interrupted power the mini pressure switch the contactor and the transformer Cie Pee When the compressor short cycles it feels very hot to the touch 274 DETERMINING THE TONNAGE REQUIRED FORA NEW AIR CONDITIONER The geographical location and construction of the building in which a new air conditioning unit is to be installed are important factors in determining the cooling requirements The better insulated the building the less heat penetration in summer and penetration of cold air in winter hence the lower the tonnage requirement for an air conditioner A building in San Francisco requires less energy to cool than one in San Antonio Texas because the climate in San Francisco is mild The number of people that occupy the conditioned area and their activity are other factors that affect the heating and cooling requirements for determining the size of the unit Also take into consideration the number of light bulbs and heat producing appliances involved In the case of heat producing appliances the total load can be determined by multiplying the wattage of all the appliances by 3 4 EXAMPLE Ten light bulbs of 100 watts each would be 1000 watts x 3 4 3 400 Btu Consider 500 to 1000 Btu f
410. preparation refrigerator Note location of condensing unit behind grille Rear view of a typical refrigerator case Condensing unit behind grille Commercial kitchen self contained refrigerator freezer Condensing unit located on top behind grille Bottom left Inside of a typical walk in cooler Arrow under evaporators points to condensate water drain hose 216 COMPRESSOR TROUBLESHOOTING CHART COMMERCIAL AND RESIDENTIAL UNITS Problem and Possible Cause Suction Pressure Too Low Low refrigerant Restriction in liquid line filter drier Clogged expansion valve strainer Kinked tubing Insufficient refrigerant passing through valve Evaporator fan runs too slow Suction Pressure Too High 1 Refrigerant control valve open too far 2 Low compressor suction power 3 System overcharged Discharge pressure too low Refrigerant charge too low Leaky discharge valve Cold water flow too high Bad refrigerant control valve Discharge Pressure Too High Condenser linted or blocked Air or moisture in system Too much liquid in receiver Water flow too low Water too warm at inlet High Pressure Cut Out Causes Compressor to Stop Too much refrigerant Cut out setting incorrect Water cooling failure Water pump failure Water line clogged Add refrigerant Replace filter drier if it feels cold Remove and clean Inspect all tubing particularly between expansion valve
411. pressure dirty filter 10 Contactor winding shorted 10 Check continuity in winding replace contactor if necessary 11 Bad wall thermostat 11 Check or replace as necessary Low pressure switch open Condenser Fan Runs But Compressor Does Not Start 1 Compressor motor bad 2 Overload protector or capacitor defective 3 Loose connection 4 Defective contactor Check or replace as necessary Check or replace defective part Check and tighten as necessary particularly compressor terminals Check or replace contactor Compressor Runs But Evaporator Fan Motor Does Not Start Bad fan motor or capacitor Loose connection Bad fan relay Fan blade or blower obstructed Compressor Stops Before Thermostat Is Satisfied Condenser dirty Low voltage Condenser fan speed too slow Dirty filter s Defective run capacitor Replace defective part Check and tighten Check and replace as necessary Adjust motor mounting to clear fan blade or blower wheel Clean condenser coil and fins Check for required voltage Check for loose blower wheel Clean or replace Check and replace if necessary 278 Problem and Possible Cause 6 Defective compressor motor 7 High or low pressure control switch inoperative Unit Does Not Cool Sufficiently Thermostat set too high Thermostat improperly located Compressor and or condenser fan not running Dirty condenser and or evaporator Dirty filter
412. proper fire extinguisher available especially when brazing or using a torch Prevent severe shocks by discharging capacitors before touching them Use a capacitor discharger by following the instructions in this book Never use any gas other than Refrigerant printed on the name plate for developing pressure in residential refrigeration systems Avoid contact with liquid refrigerant It can severely burn your skin When working outside and plants or shrubs are downwind do not allow the refrigerant to be released into the air as it kills grass and other small plant life Always unplug the unit before beginning any electrical or mechanical work Always use a three wire extension cord or power supply cord This is the common grounded three prong plug found on most new appliances It is dangerous to personnel and the equipment to disregard proper grounding techniques When transferring liquid refrigerant from a storage cylinder to a service cylinder never fill it completely full the pressure buildup can cause the cylinder to explode Always keep refrigerant containers and acetylene and oxygen cylinders away from any heat source or flame 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Compressor oil mixed with refrigerant system may become acidic Avoid burns by using rubber gloves and safety glasses Always remove the refrigerant from a system before brazing This can be done by installi
413. psi for units using R 500 and 295 psi for units using R 502 Some units use a combination high and low pressure control See fig 93 HOW TO CHECK THE HIGH PRESSURE CONTROL Connect the high pressure gauge to the high side service valve Open the valve Disconnect the condenser fan or block the airflow or if it is a water cooled system shut off the flow of water As the temperature rises 144 so does the head pressure If the gauge goes over 10 above the correct head pressure and the control fails to shut off the compressor disconnect the power and adjust the high pressure control to a correct setting or replace the control if necessary CAUTION Perform this check for a brief time only to prevent damage to the unit Ill OIL PRESSURE SAFETY CONTROL This type of control is used in heavy commercial and industrial refrigeration They have two lines with flare nut connections one is connected to the compressor oil line usually located directly on the compressor and the other one connects to the suction line Because the discharge line pressure causes some amount of oil to leave the compressor and circulate with the refrigerant this oil must be returned to the compressor from commer ialsyst ms the compressor suction line to maintain the basis of the oil and suction line proper lubrication If the low side pressure Pressure difference goes higher than the oil pressure the oil will Figure 94
414. quid state This is what happens as hot refrigerant vapor is forced into the condenser coil and that is why the condenser feels warm 7 THE PRINCIPLE OF REFRIGERATION Heat is absorbed from the inside of a refrigerated area through the evaporator coil It is then delivered to the condenser where it is dissipated in the air outside the refrigeration unit Look at figures 1 and 2 to see the route the refrigerant takes and how it vaporizes or changes back into its liquid state as it is circulated through areas under different pressures The compressor is the heart of a refrigerator freezer air conditioner ice machine etc all of which operate on the same principle The compressor circulates refrigerant throughout the system by creating a pressure difference The compressor suction power from its suction port reduces pressure in the evaporator causing the refrigerant to vaporize upon reaching there absorbing the heat in the freezer compartment essentials 1 and 3 It is then drawn into the compressor and compressed and forced into the condenser through the compressor discharge port This action creates high pressures that speed up the refrigerant molecular motion causing the cold vapor to change to hot vapor In the condenser coil this added heat and the heat absorbed in the evaporator is radiated into the surrounding air causing the vapor refrigerant to cool down and return to its liquid state essentials 2 and 4 H
415. quire more torque to start They are widely used in commercial refrigeration and appear similar to the current magnetic relays but work by voltage fluctuation As the speed of the motor increases voltage is increased This causes the winding in the relay to create more magnetism forcing its contacts to open disconnecting the power to the compressor start winding By the time the motor reaches two thirds of its normal speed the contacts within the relay are opened The contacts are normally closed See figs 48 and 49 Thermal relays A bimetal metal strip is installed within the relay A resistance wire is mounted close to the bimetal strip As current flows to the compressor start winding through the resistance wire the resistance wire heats the bimetal strip causing it to flex and open the contacts within the relay interrupting the flow of current to the compressor start winding By the time the contacts open the motor reaches its operating speed Its contacts are normally closed Solid state electronic relays These relays are not sensitive to motor size therefore they can be used for a variety of motors from 1 12 to 1 3 hp Diodes and triacts are used in their construction 74 Figure 51 When the motor reaches a predetermined speed it automatically disconnects the power supply to the compressor start winding Solid state relays are replaced and not repaired See fig 50 The best way to test the start
416. r Compressor start capacitor NOTE There is a strainer located two Relay inches below the capillary tube and Retainer strap and nut the condenser coil joint That strainer Controlipanel is often the cause of a restricted system rather than the capillary tube itself It can be removed for cleaning or replacement by cutting the tube leaving the condenser coil two inches below the capillary joint A replacement Tia screen is necessary as replacement replacement filter driers come with a screen TYPICAL STRAINER LOCATION 0 Figure 142 Fig 45 gives more information about the different sizes and lengths of capillary tubing required for the various horsepower ratings of compressors The principle involved in the operation of these air conditioners and the techniques used in their repair is the same for all small refrigeration units 236 FANS FOR AIR CIRCULATION Fans circulate the air in the environment to be conditioned fet well as circulating it through the evaporator and condenser coils In a simple wall mounted or window air conditioning unit the fan draws the room air in through the cold evaporator coil and returns the chilled air to the room through the grille This fan motor usually has a shaft and blade on the other side that draws the outside air in through a grille and blows it back out through the warm condenser coil to help cool the condenser The fan on the con
417. r Higher than normal head pressures are caused by the following 1 Restriction in the sealed system As the compressor discharge line keeps pumping against the restriction it creates high pressures in the condenser and the liquid line 2 In the case of water cooled condensers poor water circulation or presence of air bubbles in the water 3 Too much refrigerant in the system Some of the refrigerant must be released by using the manifold gauge a Connect the high pressure gauge hose to the access valve on the discharge high side of the compressor while the valves on the manifold gauge are closed Turn on the unit c Turnthe high pressure gauge valve on and off in short intervals and check the gauge d By repeating this procedure a few times enough refrigerant is released to bring the reading within normal range 4 Ambient temperature above 85 F It is normal to have a higher head pressure in the summer with higher ambient air temperatures 5 Dirty condenser When a condenser gets covered with grease lint and dirt the necessary heat transfer to change the refrigerant from vapor to its liquid state does not take place Consequently head pressure goes higher than normal and the unit no longer cools AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 181 In places where pets such as dogs and cats are kept indoors the condenser requires cleaning more often as hair shed by the pets is drawn into the fins and coil an
418. r This is the defrost cycle Touch the ohmmeter probes to contacts 3 and 4 the meter should register a continuity reading If not replace the timer Touch the two terminals connected to the timer motor numbers 5 and 6 The meter should register an ohm reading If not replace the timer Turn the dial slowly clockwise If you feel any snag replace the timer If you notice any charring or burn marks on the terminals replace the timer Also if the timer fails to change cycles check the terminals connected to the timer motor numbers 5 and 6 with a test light to make sure proper voltages reaches the timer In cases where the timer motor operates on low voltage 40 24 or 12 VAC if the test light doesn t glow check the transformer Figure 54d Hautral FEL Defers Heg Torra Hot Line 54 TESTING RESIDENTIAL TIMERS Check the make of the unit and identify the timer terminals in these diagrams Turnthe timer cam clockwise to change cycles The shorter distance between the clicks identifies the defrost cycle The longer distance between the clicks identifies the cooling cycle Place the ohmmeter probes on terminal 1 and on terminal that activates the timer in that particular cycle The meter should register a continuity reading or a no continuity reading between terminal 1 and on terminal that is out of that cycle mu ne
419. r 110 VAC power supply etc Put the voltmeter probes into receptacle A fig 34 Plug the unit into socket B while keeping an eye on the voltmeter needle If atthe first instant the unit is plugged in and starts running the voltage drop registered exceeds or falls under the minimum compressor requirement chances are that there is too much load on that particular circuit Advise the customer to have an electrician provide the unit with an independent line to meet the requirement of the compressor manufacturer 53 54 A QUICK CHECK FOR COMPRESSORS THAT FAIL TO START CAUTION These tests have some shock hazard Do not touch any wires until the power source is disconnected Unit dead Won t run No hum Insert the two check light probes into the power receptacle a Light won t glow b Light glows Set cold control at its lowest setting Remove compressor compartment cover in the back of the unit Remove the compressor plastic terminal cover with a screwdriver blade Connect the two test light alligator clips to the two relay terminals that connect it to power a The light glows b The light won t glow Connect the two test light probes to the two terminals behind the compressor compartment cover where the power cord connects to the unit Plug the power cord into the power receptacle a Ifthe light won t glow replace the power cord b Iflight glows proceed Find the cold control thermos
420. r if there is any unusual noise replace the fan motor In some units the fan motor will not operate if the freezer door is opened find the push button around the freezer door and push it while the door is open and listen to the fan If you can hear the fan or if it sounds like it is operating at a reduced speed 2 Disconnect the power 3 Remove the evaporator cover explained earlier in Testing the Defrost Limit Switch and remove the fan support plate A long running time with an inoperative fan can be evidenced by an accumulation of ice on the evaporator plate 4 Ifthe fan does not run check to see if there is power at the motor terminals with atest light As explained in Testing the Condenser Fan Motor step 4 Take care not to touch any live wires while the unit is plugged in If there is power at the fan motor and it is not running replace the fan motor Sometimes defective fan motors run for a while but due to an internal short after a brief period of running heat up and stop operating Sometimes AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 85 the fan runs but it appears not to be running at full speed This ohmmeter test will determine whether or not it is defective If the ohmmeter registers a reading 5 beyond the factory ohm rating or if no continuity reading is registered replace the fan motor Refrigeration units manufactured by General Electric in particular and many other brands come with
421. ransformer voltage requirement can be easily read There are many types styles and sizes of transformers available Your only concern when buying a replacement is the specified primary input and secondary voltage output and rating AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 243 RELAYS A relay is an enclosed electromagnetic switch and comes in several types and styles see fig 151 Relays operate on 24 VAC and 40 VAC but seldom on 12 VAC or line voltage The low voltage Fig 151 A Diagram of a commercial urit B diagram on operating the relay is created back of pater star rely T HO back of parterrrial starter by a transformer installed in the P 0 3 starter relay relay backa with diagrams showing nanmaldy open and normally closed electrical circuit see fig 153 contacts E VNC relay for heat pump aed jaj 24 WAC relay used in air conditioners for electric heat Three sets of wires connect to 151 relay terminals one set carries line voltage or low voltage to energize the relay depending on the type of relay another set connects the relay terminals to a different controlled load circuit s and a third set of wires connects the relay contacts to the power supply When the coil is energized all the normally open contacts close energizing circuits that are interrupted by the relay and at the same time all the normally closed contacts open to
422. rator plate Correct water line position Check for restriction in overflow tube make sure overflow tube is properly inserted in liner drain and check for worn water valve washer 202 One of the better products on the market for cleaning evaporator plates is nickel safe ice machine cleaner made by Calgon Vestal a division of Calgon Corporation This or a similar product is available at refrigeration supply businesses It comes in a 16 oz bottle with the directions printed on the back which are reprinted here to provide an outline of what is involved DIRECTIONS 1 Turn off refrigeration shut off water supply and remove ice from bin 2 Remove water trough water curtain s water distribution tube s and other parts that may be scaled with deposits 3 Mix3 oz of nickel safe ice machine cleaner per gallon of water in plastic container and place components in solution Soak the components until they are free of deposits For stubborn or thick deposits use a soft brush to help the dissolving action 4 Useabove solution to clean storage bin top bottom and side extrusions and other components where deposits have collected then rinse cleaned areas with fresh water 5 Replace cleaned components and turn on water 6 To clean evaporator as well as the remaining recirculating water system add nickel safe to the water in ice maker according to the manufacturer s instructions If none are available use 5 fl oz of nickel safe p
423. rawn in and circulated through a cold or warm coil or an electrically heated element or a gas type heat exchanger and forced back into the conditioned area In the cold seasons since the heating of air causes the humidity to drop figs 132 a and b some water is vaporized and mixed with the return air to rehumidify the conditioned area In summertime the air conditioner draws the inside air through the evaporator coil and returns it to the conditioned area As the air cools its humidity is increased figs 132a and 132b To eliminate the excess humidity a second cold coil is used to collect condensation as the cooled air is drawn through the unit by a blower fan s This moisture extracted from the chilled air flows to the outside through a drainpipe This coil is referred to as a dehumidifier which is nothing more thana glorified term for an additional evaporator coil installed in the system or as an independent unit Air conditioning consists of six major functions 1 circulating air by blowers or fans 2 ventilating air 3 heating air by bringing it into contact with a heating element 4 cooling air by bringing it into contact with cold coil of an evaporator 5 humidifying and 6 dehumidifying as explained earlier In small wall mount units as air comes in contact with the cold coil the moisture in the air condensates and drips into a pan underneath then it flows into a drainpipe and to the outside by gravity In la
424. re current when it is in its starting stage than what it draws during its normal speed This causes a high amperage flow into the motor through the starting relay when the compressor is energized The high amperage flowing through the relay winding creates a magnetic field causing the contacts within the relay to close and supply power to the compressor start winding As the compressor motor picks up speed it draws less current By the time it reaches two thirds of its normal run speed the reduction in current flow causes the magnetic field in the relay winding to become weak and then gravity separates the contacts and disconnects power to the compressor start winding At this point the compressor run winding takes over and brings the motor to its full running speed Current type relays are widely used in residential units Also see fig 45a Figure 47b Courtesy of Johnson Controls AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 73 Figure 48 A typical commercial type potential relay which is not mounted on the compressor terminals The contacts in a potential relay are normally closed Figure 49 POTENTIAL TYPE RELAY MOUNTED ON THE COMPRESSOR TERMINALS Figure 50 SOLID STATE ELECTRONIC STARTING RELAY Courtesy of White Rodgers Division of Emerson Electric Company Potential relays are often called voltage relays These relays are used with larger capacitor start compressor motors which re
425. re 200 EsUtsesrsal liper Lire Reselect the compressor replace the direct drive motor for proper speed or reduce the compressor speed by installing the proper size pulleys If the evaporator design capacity is less than the actual load match the evaporator to load requirements Tharzal Expansion Distributor Vale 11 3 Uneven or Inadequate Evaporator Loading and Low Superheat This is caused by poor air circulation through the evaporator coil as one or more of the evaporator fan motors may be inoperative You will need to replace any inoperative fans increase the evaporator fan speed Since the TEV function is to control superheat at point C it only makes sense that we obtain the variable opening and closing forces from that location This can be achieved by using an externally equalized valve see fig 201 The externally equalized TEV senses the true closing pressure P2 at the outlet of the coil instead of pressure A at the inlet Now pressure drop through the coil no longer affects the operation of the TEV Figure 201 Figure 202 Externally Equalized TEV Internally Equalized TEV Plea a zm Al PUT pl i fp Pirih pemsitra X ld mad 2 Eod Thermal Expansion Valve with Thermal Expansion Valve with external equalizer on evaporator internal equalizer on evaporator with 10 psig drop with 10 psig drop O21V JO sa1ino5
426. re drop according to the unit size and the liquid line tubing size in a system using R 12 As an example suppose you were to calculate the pressure drop in a two ton system using R 12 that has one hundred feet of one half inch tubing in the liquid line and has a ten feet vertical rise a valve four 90 elbows and two tees Figure 178d shows that a valve on one half inch tubing has an equivalent pressure drop to two feet of added tubing four 90 elbows have the equivalent of four feet of tubing and two tees also equal to four feet The ten feet rise adds the equivalent of another five feet of tubing Add them all together to determine the liquid line pressure drop in this particular system one hundred feet liquid line 100 0 valve 2 0 four elbows 4 0 two tees 4 0 a ten feet rise 5 0 Total 115 0 According to figure 178f 115 feet of 1 2 inch liquid line has a pressure drop of 1 84 lbs if the system uses R 12 To give you a better understanding according to figure 178f the pressure drop in a three eighth inch liquid line of a 48 000 Btu h four ton unit circulating 286 R 12 is 0 450 psi ft If 100 feet of liquid line were used 45 psi 100 x 0 450 pressure drop would be applied at the TEV If the unit were to normally operate with a 130 psi head pressure the head pressure in the liquid line at the TEV would be reduced to 85 psi 130 45 85 According to the chart on page 124 at 84 2 psi the closest to 85 psi R
427. re relief valve As the cylinder fills pressure builds inside until it becomes equal to the pressure inside the refrigerant cylinder At this point the cylinder stops filling Relieve some of the pressure by opening the top relief valve very little then close it again The cylinder will resume filling When buying a critical charge cylinder be sure to get one with a pressure gauge on top When the cylinder is adequately charged plug in its electrical cord to a 115 V outlet The cord is connected to the cylinder heating element As the element heats pressure is built up in the cylinder This pressure is used to force the refrigerant into the unit being charged NEVER FILL THE CHARGING CYLINDER ALL THE WAY TO THE TOP 112 Generally building up a pressure between 150 and 200 psi is enough for most units DO NOT ALLOW THE PRESSURE IN THE CHARGING CYLINDER TO EXCEED 275 PSI WARNING When the cylinder is plugged in do not leave it unattended It will take a few minutes to build up pressure Too much pressure will cause the cylinder to explode If the amount of refrigerant charge cannot be found on the nameplate or if for any reason it cannot be determined get the information from the book Tech Master for Refrigerators and Freezers published by Master Publications Euclid Street Santa Monica California 90404 The reason the refrigerant cylinder is inverted when filling a critical charge cylinder is to allow liquid refrigerant to
428. red operating results If the TEV installed uses or is suspected of using the wrong type of charge check the specifications of the valve and compare them with the operating specifications of the unit and select the proper charge based on the system refrigerant and the desired operating performance l 14 Measuring and Adjusting Operating Superheat Measuring Determine the suction pressure or saturation temperature at the evaporator outlet with an accurate gauge Determine the saturation temperature at the observed suction pressure using the temperature pressure chart Measure the temperature of the suction gas at the remote bulb location as follows a Clean area of the suction line at the bulb location and tape the thermocouple on the cleaned area b Insulate the thermocouple and read the temperature with an electronic thermometer Subtract the saturation temperature determined in step 2 from the sensible temperature measured in step 3 The difference is the superheat of the suction gas at the evaporator outlet Adjusting w Requires operational head pressure and a solid column of liquid refrigerant at the TEV inlet Refrigerated space must be under a full load condition Evaporator pressure regulators EPRs must be in a fully open position On a multicompressor system extra precautions are required ensure a constant suction pressure a constant discharge pressure and a constant receiver outlet pressure are all at proper l
429. rgement of the end of one tube to allow another tube of the same size to be inserted into it switch A device to connect or disconnect an electrical circuit temperature The degree of hotness or coldness measured on a specific scale such as a thermometer terminal A device attached to the end of a wire or to an apparatus for convenience in making electrical connections 430 termination switch See defrost bimetal test light A bulb with a pair of leads used in testing a specific range of voltages thermistor A semiconductor in which the resistance varies with its temperature thermostat An automatic heat sensing device for regulating temperature by opening and closing an electrical circuit thermostatic expansion valve TEV A valve operated by the temperature and pressure in the evaporator to control the flow of refrigerant throttling Expansion of gas through a controlled opening transformer A device with two sets of windings that will generate the desired voltage s from its secondary winding tubing Pipes that carry the refrigerant Usually made of copper aluminum or steel two temperature valve This valve is located in the suction line at the outlet of the warmer evaporator in multiple evaporator systems When a different temperature is required in each evaporator this valve maintains a predetermined pressure and consequently temperature in the warmer evaporator vacuum A space exhausted to a high degree by an
430. rger central air conditioning units since there is much more air to be dehumidified an extra cold coil is installed to collect and condensate moisture from the air AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 229 This moisture is collected in a pan and conveyed to the outside by a pump or by gravity See fig 134 14 cipi e et To gs danme hued etic controls a in a forced amr onesie bhauwting pee wilerrai cal y form the eni ur Off ai preset possi During cold seasons heated air becomes drier Some central air conditioners provide added moisture by evaporating water in a pan kept replenished by a float mechanism installed in the pan which operates a switch in the electrical circuit of a solenoid water valve This water is vaporized by an electric heating element installed in the pan The vaporized water is then circulated in the conditioned area by a fan or blower The operation ofthe electric heater and the blower is controlled by a humidistat Figure 135 shows a basic humidifier in which the rotation of a belt made of a porous material and a heater cause a rapid vaporization of the water which is blown into the conditioned area A HDFPIDAFIER then wrier the dari longes dry sir throug it ned peri rhe mature li erni the mpm e Horn rl fanc sir rrr P pua nett Aare 115 There are basically two different systems employed i
431. rical defects such as a short or a disconnection in the timer motor causing it not to advance Occasionally a timer motor freezes in one particular cycle and no longer advances because of a mechanical defect Disconnect the power supply Turn the timer shaft to a point just before a click is heard and leave it there Using a test cord with insulated alligator clips connect timer terminals 1 and 3 directly to the power supply where the unit is normally connected If the timer motor starts turning it is good Otherwise disconnect it from the power and replace the timer In some timers you cannot see the motor rotation through its housing In which case wait for about fifteen minutes if you hear the click the timer is good Otherwise replace it 78 HOW A COMMERCIAL TIMER WORKS As you can see in figure 54b only one of the power lines is connected directly to the loads compressor fans and defrost heater The other power line runs through the timer terminals before it reaches the loads to energize them The timer motor operating on a twenty four volt power supply opens and closes contacts at regular predetermined intervals causing the loads to become energized or de energized taking the unit to the defrost or run cycle The frequencies and lengths of these intervals are regulated on the timer dial There are two sets of contacts in the timer 1 The normally closed contacts terminals 1 and 2 and 2 the normally open co
432. rigeration This occurs when the wrong type of oil 15 As a general rule of thumb externally used Different types of lubricant are used for different equalized TEVs are used where temperatures pressure drop in the evaporator is A FLOODED EVAPORATOR AS THE RESULT OF TOO Much Me than REFRIGERANT FLOW IS EVIDENCED BY A FROSTED OR a psi through an evaporator in SWEATING SUCTION LINE high temperature application 2 psi through an evaporator in a medium temperature Turn valve stem 1 4 turn at a time Then wait for about five minutes for a partial frost pattern to appear on the evaporator coil The six most usual causes of this condition are the following 1 Pressure drop too great in the evaporator coil Replace application valve with one using an equalizer 1psithrough an evaporator in a 2 Thermal bulb with wrong charge Replace valve with one low temperature application having the correct charge Always use externally equalized 3 TEV orifice adjusted too large Turn valve stem TEV when a distributor is used clockwise See fig 200 Depending on the 4 Thermal bulb installed too far from evaporator or loose make size and the number of from suction line Correct as necessary outlets the pressure drop across 5 TEV needle stuck open Replace valve the distributor alone can range Undersize evaporator This rarely occurs Replace evaporator anywhere from 5 to 30 psi An externally equalized
433. rigeration units employ hermetic compressors This means that the compressor with its motor are sealed in an airtight canister as opposed to belt driven compressors When energized it creates enough pressure difference to circulate the confined refrigerant in the entire sealed system See fig 1 Through the compressor suction side vapor refrigerant in the evaporator is drawn in and changed to hot vapor by compression It is then forced into the condenser through the compressor discharge tube where it is cooled to its liquid state again before reaching the evaporator An efficient compressor must be able to remove the refrigerant vapor at the same rate that liquid refrigerant enters the evaporator and vaporizes The low pressure side of the compressor is connected to a tubing having a larger diameter than that of the high pressure side Generally in a regular residential unit a good compressor should create a pressure between 15 inch of vacuum and 22 psi on the low side and between 80 psi and 160 psi on the high side at ambient air temperature of 70 F These pressures are checked by installing access valves such as piercing valves on the copper tubing on the suction and discharge lines of the compressor see fig 79 The installation of piercing valves mainly applies to the residential units as compressors used in most commercial systems are equipped with service valves see figs 32 118 and 120 Many refrigeration problems can be p
434. rmation 113 Causes of high head pressure 180 181 182 Compressor Adding oil 68 Burnout 174 175 Hard start kit 63 Hermetic 61 62 How to identify unmarked terminals 58 59 Short Cycling 171 172 173 Starting a stuck compressor 60 Supply voltage checking 53 Testing by using an Ohmmeter 57 Testing by using a test cord 56 Testing compressor power supply voltage 53 Testing by using Wattmeter 50 52 Three phase compressor installation 273 Types of compressor 48 49 61 Condenser Cleaning 181 Fan motors 33 82 83 84 85 High head pressure 180 Water condenser 212 213 393 394 Water condenser valve adjustment 390 391 392 Defrost systems 32 33 Evaporator 30 249 251 252 253 Fan 32 233 236 239 Fans 236 237 238 239 Filter drier 27 108 109 Heats pumps 265 through 271 Humidifiers and de humidifiers 228 229 Ice machines 186 through 202 Installation of Window air conditioning 230 through 234 Central air conditioning fig 249 272 253 255 Determining tonnage for a new system 274 Learning how to read electrical diagrams 306 through 353 Low side and high side float systems 169 Mini pressure control 248 Oil separator 154 Piping method for a c and 433 434 refrigeration 285 286 287 365 Pressure control commercial refrigeration 140 through 144 Questions and answers about schematic diagrams 334 through 351 Relay Commercial 243 70 71 74 75 Starting residential 26 27 73 Wiring fig 153 74 Refrigeration 7 through 10 Refrigerator Type
435. rned contacts Too small of wire gauge used in hookup Voltage out of balance on three phase supply sa moO anoD a a ae ie AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 381 V 7 Loss of Oil Loss of Oil Pressure or Oil Pressure Control Trips Out Probable Cause Insufficient oil in system Suction riser too large Insufficient traps in suction risers Suction superheat too high Lack of oil separator on systems operating below 30 F suction Low refrigerant charge Refrigerant floodback Ruptured suction line to the liquid heat exchanger Crankcase heater burnt out Iced up evaporator coil See sec 11 18 Distributor and or expansion valve too large oil dilution creating crankcase foaming or loss of oil pressure Liquid refrigerant feeding through oil separator Evaporator fan motor s not operating Defective oil pump Plugged oil pump inlet screen Worn bearings pump or compressor Oil pressure control trip out due to compressor short cycling Control voltage too high causing premature trip out Defective oil pressure control Defective compressor overload Oil pressure control wired incorrectly Remedy Add oil per specifications Check line sizing at design conditions and change tubing if correct Install a suction trap in the vertical riser per the manufacturer s specs Adjust superheat Add oil separator Add refrigerant Adjust superheat to 20 F minimum at the
436. rost thermostat and then closes its circuit by flowing to L2 the neutral terminal of the wall receptacle Power energizes the timer motor through its terminals 1 and 3 as long as the cold control thermostat is not satisfied The refrigerator lamp is always energized as long as the lamp switch is closed when door is open 310 Gwar load FPrac ector Energy Saver Seinen Mulliom Heater fri uurator T L ma Bleck Re aria 1 Water Inist i iis los i Sclancid Valvesl A d fae Md Tum Maker Heok p m istos T Optional pee i i while l Loco Pa j c Line Dw Enargirad Figure 183c Life Energized THE SAME SCHEMATIC WIRING DIAGRAM SHOWING THE FROST FREE REFRIGERATOR IN THE COOLING CYCLE The timer moves to position number 4 and takes the unit into the cooling cycle and the unit stays in this cycle for six eight or twelve hours depending upon the kind of timer used Pay close attention to the direction of the flow of current It starts from L1 the hot terminal in the wall receptacle flows into the timer from timer terminal 4 then to the compressor evaporator and condenser fan motors and then finds its way back to L2 the neutral terminal of the wall receptacle to complete its circuit Refer to page 351 for questions and answers pertaining to this diagram AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 311 iz wAC tf ir oy L
437. rosting runs out through a drain in the bottom of the cabinet With a garden hose attached water could drain directly to the outside of the house Refrigeration and Most test lights are capable FORE s SEP S Air Conditioning Service of indicating up to 600 VAC UE Technician s Thermometers Figure 10a sionpoud O21VIN JO sexuno 22 Figures 14 and 15 show different types of evaporators used in frost free cycle defrost or manual defrost refrigerators Usually frost free refrigerators and residential freezers have fan forced evaporators and condensers while manual defrost and cycle defrost units use static type non fan forced evaporators and condensers UPRIGHT FREEZERS The principle is the same as in the regular refrigerator with the exception that they come with heavier insulation and a different cold control range Normal operating temperatures in freezers range between 14 F and 7 F see fig 11 Figure 11 THE SEALED SYSTEM OF A TYPICAL UPRIGHT FREEZER uoneJodJ05 pue u11oN Jo UOISIAIG 8 1 2 In freezers with double fans one draws air from the inside of the cabinet to be circulated over the evaporator while the other one moves the chilled air from the evaporator to the cabinet Larger commercial units may have three or more fans They all move air in the same pattern Depending on the model of freezer the evaporator coil could be located in t
438. rs R 504 This nontoxic nonflammable noncorrosive liquid boils at 70 F It is normally used in industrial refrigeration applications where temperatures of 80 F to 40 F are needed It comes in tan cylinders Le X A refrigerant identification Figure 88 A variety of sight glasses a Figure 88a g UOISIAIG Sjo 3u02 uoniejodjo uo1e3 se34n05 m Figure 89 BLUE a igure Canet E A sight glass is brazed or flared into the liquid line The unit should be charged until the bubbles in the sight glass disappear Presence of bubbles indicate a shortage of refrigerant in the system Printing on the top of the sight glass rim shows that if the Freon is pink in color there is moisture in it and blue indicates no moisture Asayino There is an instrument that can be used to identify the type of refrigerant used in a system see fig 88 Follow the instructions supplied with it AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 139 A sight glass is used in commercial units to aid in determining the status of the refrigerant see fig 89 They are really liquid indicators that show the condition of the refrigerant in the system They show bubbles for a system low on refrigerant while the compressor is running Some of them indicate the presence of moisture in the system by a color change That information is printed on the sight gla
439. s 14 103 Manual Defrost 17 30 Frost Free 19 20 22 Cycle defrost 17 18 32 Short cycling of compressor 170 171 172 173 176 Saturated vapor refrigerant temperature 132 Test of knowledge 222 223 284 397 34 38 11 105 128 129 Testing Fan motor 82 83 85 Relays 74 75 71 72 Defrost limit switch 86 87 88 Capacitors 89 91 Compressor 50 51 52 54 56 57 63 67 Defrost heaters 96 97 98 Expansion valves automatic 371 388 Thermostats 92 93 Timers 76 77 78 79 80 Supply voltage 52 53 Contractors 245 246 247 Troubleshooting charts Residential refrigerators and freezers 118 121 127 Commercial ice machines 198 through 201 Water fountain 204 Refrigeration system by touch 207 208 Compressor commercial and residential 216 through 221 Central air conditioning system in cooling mode 264 Central air conditioner 227 through 282 Compressor 54 354 355 Refrigerant flow controls 357 through 373 Excessive oil frosting 374 through 381 Valves Hot bypass valve how to adjust 362 Pressure regulating reducing valve 145 146 147 359 Check valves 144 145 Solenoid valves 148 through 153 Reversing valves 156 157 Thermostatic expansion TEV valves 369 371 273 158 160 164 Automatic expansion AEV valves 158 383 384 386 Wiring Method for Central air conditioners fig 154 153 163 Residential commercial refrigerators and freezers fig 7
440. s relay must be replaced Check motor for continuity If there is none replace fan Add a few drops of oil every six months Check to see that shaft or blade is not binding Be sure blade is fastened securely to the shaft Check high and low pressures to determine if there is a restriction Repair if necessary Check to see that no furniture or other objects are placed closer than six inches from end grilles and that the grilles are clean and unobstructed Average area to be dehumidified should be no larger than 10 Mft 10 000 cubic feet for asingle unit Unit is effective only when temperature is above 65 F and relative humidity is above 60 otherwise the air is too cool and dry for efficient operation See number 3 above See number 4 above See number 5 above Check function of bimetal switch as you would on any refrigerator As you can see from the foregoing troubleshooting chart and figure 143 a dehumidifier is nearly the same as any refrigerating unit but with a different function The troubleshooting procedure is the same If the unit runs with abnormal noise check for loose parts or mounting or an out of alignment fan blade which will have to be secured or replaced Run unit about fifteen minutes before AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 283 USING A CHARGING CHART TO CHARGE ROOF TOP AIR CONDITIONERS beginning this charging method Connect your gauge manifold to the suct
441. s thirty inches below the zero on the compound gauge It is a good practice to heat the system by using an electric heater or heat lamp s and blower fans as the system is being evacuated 4 Shut off all valves and the vacuum pump and leave everything as it is for ten minutes 5 fatthe end of this period the gauges show a pressure rise either there is moisture in the system or the compressor has an internal leak or there is a leak in the system or in the valves on the manifold gauge that must be repaired before proceeding See Repairing a Leak 6 Close the valves on the suction and discharge lines and disconnect the vacuum pump from the system and connect the middle hose on the manifold gauge to a refrigerant cylinder Connect the blue hose on the compound gauge to the suction line see fig 82 start the compressor and charge the unit until the high pressure gauge reads about 75 psi 7 Runa leak detector over the joints and the valves If no leak is found complete the charging procedure Otherwise seal the leak and do steps 1 through 4 again Figure 76 Courtesy of Henry Valve Company A Before silver brazing the filter drier into the sealed system remove the valve core s of the access valve s and wrap the drier in a wet cloth to prevent any heat damage Do the brazing as quickly as possible to avoid excessive heat buildup A bidirectional filter drier used in heat pumps Asuction line filter drier Its purpose is
442. s which in turn parcel out the current to homes and businesses It enters those homes and businesses through their electric meters and then to circuit breaker boxes Fuse boxes as prime receivers are almost extinct now The main wires go to a bus bar a common conductor in the circuit breaker box for several circuit breakers Wires from each circuit breaker supply current to one particular circuit in the home or business During the construction of the home or business building the electrical contractor determines which rooms to be wired to a particular circuit breaker and also the number of outlets in each room Usually one to three rooms a home are wired to one circuit breaker the kitchen and laundry room may have two or three circuit breakers due to the increased load A standard circuit breaker is capable of 110 and 220 VAC circuits Three wires carry current into a house two 110 VAC and a neutral When one of the 110s is run into a socket along with a neutral wire a 110 socket is created If both of the 110s are run into an electrical outlet a 220 VAC socket is created and a larger outlet of a different style will be used Normally a 220 outlet is installed in the laundry room where an electric dryer is used or on a wall where a window mounted air conditioner is connected The electricity which flows through wires is composed of minute particles called electrons Electrons are exactly alike even in wires of different metals
443. s aud andl sua lanae a saxi manad im glans Bd Tia rts of prym da 209 210 Figures a b and are cross sectional views of forced air convection evaporators as used in typical open refrigerated display cases and bottled beverage coolers The fan circulates the air inside the cooler through the evaporator coil and back into the storage area again The condensing unit could be inside the unit enclosed in a metal housing located outside of the building or on the roof See figs 102a and 118 mA Lie gu e x MEET n Cross Section of a Cross section of a typical open refrigerated display case for meat products Note the location of the EE evaporator the direction of the Cross section of a typical self BEVERAGE COOLER airflow The condensing unit could contained open refrigerated display Fan be installed outside of the building case used by supermarkets Note 1 Evaporator the location of the condensing unit Foam insulation 1 Condensing unit and the evaporator 1 evaporator Air circulation 2 Evaporator 2 insulation 3 condensing unit Sliding glass door 3 Insulation 4 condensate water drainpipe 4 Condensate water drainpipe A TYPICAL APPLICATION OF OPEN REFRIGERATED CASES INSTALLED IN A LOCAL SUPERMARKET AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 211 Tome COOLER The
444. s connected in series In this type of wiring current must flow through every component load in the entire system to complete the circuit Since a series circuit provides only one path for current to flow the advantage of this type of wiring is the on off controllability of the whole circuit with only one switch In the illustration below power flows from L1 through the switch the fuse the heater and the light bulb then returns to the L2 side of the source completing the circuit If the circuit is broken opened by the switch a blown fuse burned out heater or a broken wire anywhere in the circuit the entire electrical path will become interrupted and nothing in the entire circuit will work because the flow of current will no longer be able to return to L2 to complete the circuit The main characteristic of a series wiring method is that the components with the greatest amount of resistance consume the greatest amount of power and leave too little power to energize the loads with minimal resistance When a load with a high resistance value is installed in a series circuit current flows and passes through other components without activating them as the insufficient remaining voltage does not meet their minimum voltage requirements This characteristic is evidenced in faulty household wiring where a light bulb starts glowing dim or goes out as soon as an iron ora clothes dryer is plugged into that circuit This principle has led to the d
445. s control No water circulation No power or no water supply Faulty refrigeration system Ice Slab Released Slowly All Models Evaporator plate covered with mineral buildup Defrost solenoid valve stuck in open position When ambient temperatures are too low head pressures drop below 100 Ib refrigeration slows and will slow ice formation Replace valve Check valve by lightly tapping on it If ice builds up on evaporator plate valve is faulty and should be replaced If you notice a frost buildup on evaporator plate while water pump is not running replace pump Remove clean or replace Turn switch to ON position In some models a faculty relay stays on defrost Replace relay A faulty control does not open and the unit stays in defrost cycle Replace control Check for mineral buildup on water strainer and in water lines Check power and water supply to unit Check system and repair as necessary Clean evaporator plate thoroughly Check and replace if necessary Relocate unit to where ambient temperatures are higher AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 201 Problem and Possible Cause Ice Build Up on Cutter Grids Poor connection between the power supply to the grids and the cutter grid connecting pin Broken wire in cutter grid Short Cycling of the Compressor 1 Low voltage Loose electrical connections Weak or faulty overload protector Faulty thermostat Ma
446. s have one common meme inlet and three outlets Illustration 103 is a picture of a four way valve e ald L Heat pumps and reversing appe valves should be increasing mem in volume in years to come since they conserve energy A heat pump is a central air conditioner or window unit with a reverse cycle for heating In the summer the refrigerant absorbs heat from the house and exhausts it outdoors In winter the cycle is reversed with the refrigerant absorbing heat from outdoors and releasing it inside the house The following is a detail of how the reversing valve operates Fig big From Evmaporakur To UCeompimamcr f Timeam EXPE 00 M Lina Celie vl CCD cero 152 Figures 98h and i show a schematic diagram of a four way valve typical reverse cycle heat pump system In figure 98i the system is on the heating cycle with discharge gas flowing through reversing valve ports D to 2 making the indoor coil the condenser The suction gas flows from the outdoor coil evaporator through reversing valve ports 1 to S and back to the compressor With the four way solenoid pilot de energized the slide is positioned so as to connect ports D with A and B with S When the pilot is de energized high pressure discharge gas builds up on top of the main slide The area below the main slide is isolated from the high pressure by C cup seal and exposed to low pressure suction
447. s the piston to be driven upward closing the outlet to the condenser and diverting the discharge gas to the auxiliary condenser Some valves are available with an internal bleed which drains the reclaim oil during normal operation This type of three way solenoid valve is designed to meet the requirements of high temperatures and pressures existing in compressor discharge gas applications It is specifically designed for discharge gas diverting in compressor unloading Valves for compressor unloading applications are usually designed to provide mounting directly on the compressor head In this application the valve is used for suction line use and is shown in a schematic diagram in figures 98h and 98i AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 151 When the solenoid is de energized the pilot line to the suction side of the compressor is closed This allows the suction gas to flow in the normal direction to the compressor as shown in figure 98g When the solenoid is energized the pilot port is opened This enables the piston to be driven upward closing off the suction line connection and permitting a reverse flow of the hot gas through the suction line to the evaporator for hot gas defrost Four way solenoid Se eneryined valves often called reversing valves are used almost exclusively on reverse cycle heat pumps to select either the heating or cooling mode depending upon requirements These ip Se valve
448. s to prevent any foreign matter in the sealed system from entering the capillary tube and restricting the flow of refrigerant Often a sleeve shaped screen is installed in the last part of the liquid line just before the capillary tube connection It is identified by a slightly enlarged portion of the liquid line tubing A restricted strainer is easily discovered when it feels cool to the touch It should feel about 6 F to 10 F above room temperature Evaporator Coll NO FLASH GAS AT TEV INLET FLASH GAS AT TEV INLET Figure 196c NA Fa F Liquid Lins Courtesy of ALCO Controls 362 A field installed service valve at the liquid receiver might be too small or not fully open a pipe joint in the liquid line might be partially filled with solder or a kink in the liquid line can cause a restriction Copper tubing is soft and relatively easy to twist kink or flatten The liquid line must be thoroughly inspected and any defect corrected Also the connections on the liquid receiver must be as large as the liquid line be sure there are no reducer fittings or couplings installed that would create a partial restriction in the system See the chart on page 365 for the recommended refrigerant line sizes Also replace any solenoid valve not working properly Figure 197 Figure 197a Hot Gas Tr me lisi Lina S 0J1002 40 se1uno5 Dre pi m irn i HOW TO ADJUST A HOT GAS BYPASS VALVE Connect a compound gaug
449. schematic wiring diagrams covered in detail in the Basic Electricity chapter that indicate the ohm value of each electrical component When replacing fan motors check for the watt rating and the revolution per minute of the replacement part The new fan motor should be rated as close to the original part as possible This is particularly important in commercial refrigeration considering the fan speed variation in those units Often replacement commercial fan motors come with fan blade shafts that are too long Measure the length needed and cut off the excess with a hacksaw During installation pay close attention to the direction of its rotation It is stamped CW for clockwise or CCW for counterclockwise on the back of the motor or on the nameplate The new fan motor must rotate in the same direction as the original This is made simple in commercial fan motors see fig 61 Usually two extra wires come out of the motor By connecting these two wires together the shaft rotation can be reversed Instructions to this effect are supplied with new motors Figure 60 Figure 61 BTS VERN PCR DUTCE Cleo oe eamin CREWS y T WM E Many PSC fan motors see fig 137 come with AN EVAPORATOR FAN MOTOR FOR a long double shaft The shaft is cut with a RESIDENTIAL AND COMMERCIAL APPLICATIONS hacksaw to the length needed Blades may be mounted on one or both ends These fan motors can have
450. ses of the coil in the fresh food compartment Since the thermostat sensing bulb is attached to the lower part of the coil in the fresh food compartment it never allows the thermostat contacts to open This causes the unit to run continuously and the temperature in the freezer compartment to drop below normal Figure 123 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 177 Btarting Figure 124 Dverlaad Protector Flux Type Ammatar CHECKING FOR LOSS OF REFRIGERANT WITH AN AMMETER Refrigerant loss is directly proportional to the amperage reading The less Freon in the system the lower the amperage reading This method is used mostly with commercial refrigeration units and air conditioners where the free load amperage is easily found on the nameplate SIGNS OF RESTRICTION OF REFRIGERANT FLOW A restriction of refrigerant flow is caused by the formation of ice from moist air in the system Air can penetrate into the system from a very tiny hole in the tubing perhaps caused by an improperly sealed joint flared connection or failure to properly vacuum the system if previously repaired This restriction occurs in the capillary tube TEV or AEV because they are the narrowest passages through which refrigerant flows in a sealed system When the capillary tube becomes restricted the most common complaint is that the unit sometimes seems to cool and sometimes it doesn t cool at all It acts crazy This is due to the fact that the
451. several uses such as blowers The fan is fastened to its bracket before it is ventilators condenser evaporator fans mounted on the unit 86 TESTING THE DEFROST LIMIT SWITCH Defrost Bimetal or Defrost Thermostat A defrost limit switch is a bimetallic device that opens and closes the circuit to the evaporator defrost heater during the defrost cycles in frost free units In this cycle the timer disconnects the power supply to the This illustrates one way of testing compressor and at the same time a defrost thermostat connects power to the evaporator Disconnect poweranddisconnect defrost heater to melt the ice built thermostat from system upon the evaporator surface see fig Connect ohmmeter to the two wires on the defrost thermostat 62 The current to the evaporator Spray some CO on the heater passes through this bimetal thermostat and the ohmmeter device which controls the on off dial should deflect to a zero reading function of this circuit Since this device is mounted on the evaporator coil once sufficient frost builds up to cause it to contract it closes the circuit to the heater As the timer takes the unit into the defrost cycle the heater melts the ice the coil becomes warmer causing the device to expand and open the circuit to de energize the defrost heater Figure 62 Because the bimetal switch is clipped to the evaporator in the freezer compartment the evapora
452. sidered a flooded system During the run cycle liquid refrigerant is forced into the high side float chamber through the condenser As soon as enough liquid refrigerant enters the float chamber the float ball moves up allowing the refrigerant to flow to the evaporator Because the evaporator is under low pressure the line entering it should be insulated Often a capillary tube is used on the line connecting the high side float chamber and the evaporator If not a weight valve should be installed to prevent the liquid from evaporating in that connecting line Refrigerant enters the evaporator under low pressure evaporates and absorbs heat from the evaporator It then flows through the suction line into the compressor where it is forced out under high pressure into the condenser again The condenser then removes the heat absorbed in the evaporator changing the vapor refrigerant back into its liquid state before it is forced into the float chamber to repeat the cycle NOTE The amount of the refrigerant charge in a high side float system must be measured very accurately for the proper operation of the unit Liquid receiver tanks are used on all units with a high side float system Units with capillary tubes use an accumulator installed at the outlet of the 170 evaporator The motor control temperature sensing element is installed on the coil just before the accumulator on the suction line Liquid receiver tanks are used on all units with a h
453. signed to permit charging or recovery of refrigerant by weight into any air conditioning and refrigeration system or cylinder A four way digital gauge set with sight glass The combination low side gauge reads from 30 inHg to 99 9 psi and displays both vacuum and pressure readings Astandard manifold gauge set manufactured by the same company Courtesy of TIF Instruments Inc NOW AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 407 STEP BY STEP RETROFIT INSTRUCTIONS FOR SUVA 134a Remove R 12 from the system 20 inHg vacuum is needed to remove charge Drain the existing oil from the compressor Small hermetic compressors which have no oil drain must be removed from the system to drain the oil out through the compressor suction line In larger systems oil must be removed from low spots around the evaporator All existing lubricant must be drained from the oil separator too Measure the total volume of oil drained from the system Recharge the system with an equal amount of Polyol Ester Lubricant Reinstall compressor if necessary Replace filter drier with one compatible with SUVA 134a Evacuate system to 30 inHg use a vacuum pump Using normal service practices check system for leaks Check with the manufacturer of your leak detector for its sensitivity to SUVA 134a If any leak is detected seal leak and re evacuate system Charge system with SUVA 143a Charge 90 by weight of the amount of the original
454. sket the retainer strip and then screwed into the main door panel Chest type freezers are generally equipped with compression gaskets having three or four sides with a magnetic strip along the front to give the lid a leakproof seal If these gaskets are to be OF EL Hok pig 2 1 Hr pa blrrg tebe pe in sold moie door fies inode that have tim GI avus hohe 3 Docs bar Hir indir Jor nderit eos diae mg removed use a screwdriver to pry out the clips Accumulation of dirt and grease on a gasket makes it sticky and as the door or lid is opened and closed the gasket tears or pulls loose or sometimes the door liner cracks Door liners can also crack because of excessive pressures caused by incorrectly positioned food products that prevent the door from closing properly 100 Clean sticky door gaskets with a mixture or vinegar and water or glass cleaner Rinse with clear water and dry with a towel Vinegar water mixture is also a good food compartment cleaner and deodorizer The upright unit should be tilted a little to the rear to allow the door s to swing closed from a 45 angle A poorly fitted gasket in most freezers and refrigerators can be adjusted by the hinges and the door latch Warped doors can be straightened by twisting or adjusting the gasket screws DOOR SEAL INSPECTION AND ADJUSTMENTS 1 Visually inspect the condition of the door seal
455. sor mounting nuts and bolts Unit not level Tubing vibrating or touching cabinet Drip tray vibrating Fan blades striking object Defective gasket or seal Defective case heater or mullion heater Accumulation of ice in the cabinet insulation Broken starting winding Broken run winding Broken compressor valve Overheated compressor Leaky door gasket Clogged drain hose Evaporator drain hole plugged Timer stuck on defrost cycle Defrost drain plugged Cabinet not level causing poor drainage Blocked air ducts Kitchen humidity too high Defective door gasket Brace flooring Tighten or replace mounting nuts and bolts Level the unit by adjusting legs Move tubing wedge or tape to stop noise Place tray on pad or tape in place Adjust fan mounting or move object Check gasket for hardening cracks or dirt Check both heaters and replace if necessary Unplug unit for forty eight hours and allow ice to melt Dry insulation seal cabinet leaks and reassemble Replace compressor Replace compressor Replace compressor Replace compressor Inspect and replace if necessary Clean inside of hose so water will drain Clean drain passage Turn timer knob If unit starts running replace the timer Clean defrost drain Adjust legs to level unit Remove object s obstructing cold airflow from freezer compartment to fresh food compartment Sweating will stop
456. ss SURGE TANK When two evaporators with two different temperatures are used in a system a two temperature valve is installed at the outlet of the warmer evaporator to prevent the compressor suction power from bringing the pressure in the warmer evaporator lower than the desired pressure Look at figure 96 to see where the surge tank is installed When a two temperature valve is used the compressor short cycles unless a surge tank is installed in the suction line The reason for this is that immediately after the pressure in the suction lines drops to a predetermined cut out setting a switch in the low pressure control opens shutting off power to the compressor causing the two temperature valve that controls the pressure inside the warmer evaporator to open causing a rapid rise in the suction line At this point the switch in the low pressure control sensing the increase in pressures closes its circuit and starts the compressor and causes the short cycling The surge tank prevents this by creating more low pressure volume to absorb the sudden pressure rise that might affect the low pressure control It could be said that it is a type of shock absorber that smoothes out the fluctuations of the suction line pressure changes HANE Re AND ALCP UNIT Woitaide concen oer deletion of the omore layer oral irrreusizg coals ul refrigerant makes Peeling and neirigerants practicel mcd economical A saion I
457. ss disappear The operating amperage is increased as more refrigerant is put into the system Therefore overcharging the system drastically reduces the life of the compressor motor The correct amount of refrigerant in central air conditioners is directly proportional to the amount of piping used between the evaporator and the condenser As the length of the tubing increases the amount of refrigerant charge increases A C manufacturers usually attach a step by step charging chart inside an access panel of the condensing unit such as the following method of charging which is practiced most by the service personnel who work on Carrier A C units Figure 178c 1 a 6 ERT TEMPERATURE 2 T SETIN Lint F 284 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 A TEST OF KNOWLEDGE On Air Conditioners What are the five reasons for a dehumidifier to run but not dehumidify p 282 What are the possible causes of a circuit breaker tripping as soon as a window air conditioner is turned on p 280 What happens when there is a restriction in the airflow in a central air conditioner p 279 What four causes would keep a compressor from shutting off in a central air conditioning system pp 277 278 In a central air conditioner what are the possible
458. ssures in the sealed system It comes in cylinders or cans color coded green R 11 This refrigerant is widely used in very large units with large centrifugal compressors it is also used as a flushing agent With a boiling point of 50 1 F at sea level it is used where temperatures of 60 F to O F are required It is 138 mainly used in frozen food display cases frozen food processing plants ice cream freezers and ice machines that work with reciprocating compressors It is considered a low pressure type of refrigerant R 11 cylinders are orange colored R 502 This is a combination of R 12 and R 22 with a boiling point of 50 1 F used basically for low temperature operation between 60 F to O F in ice machines frozen food display cases frozen food storage cabinets and industrial refrigeration in frozen food processing plants It is nontoxic and nonflammable It creates relatively low condensing pressure head pressure at low temperature It is used only with the reciprocating type of compressor The cylinders are color coded orchid R 503 This refrigerant boils at 126 F at sea level Because of this it is used where a very low temperature range is needed 125 F to 100 F such as in the low state of cascade systems Because of such low temperatures the oil in the compressor tends to freeze if oil separators are not used to return the lubricant to the compressor This refrigerant comes in aquamarine cylinde
459. stat is set on HEAT and AUTO The RVR reversing valve relay is energized and its normally open contacts close This will cause the reversing valve solenoid to become energized in the 220 VAC circuit and the control relay to become energized in the 24 VAC circuit When the reversing valve solenoid is energized the outside coil will act as an evaporator and the inside coil will become a condenser to heat the conditioned area The two thermostats TH 1 and TH 2 are within the wall thermostat unit and are designed to perform two different stages of heating TH 1 is manually controlled by the user When TH 2 senses a need for additional heating it will close the circuits to the outside heaters HR 1 and HR 2 which in turn are controlled by the two thermostats clipped to the outside coil ODT1 and ODT2 thus commencing the second stage of heating HR 1 and HR 2 are installed on the outside coil ODT1 and ODT2 are both affected by outside temperatures Since the outside coil temperature is set about 20 F below the average ambient temperature this temperature difference is heat which is transferred to the inside coil now acting as a condenser Considering the low temperatures in winter the outside coil temperature tends to drop very rapidly The heating of the outside coil will help alleviate this problem and increase the heating efficiency of the unit When the wall thermostat is set on COOL the TC cooling thermostat closes a circuit to e
460. structions come with a new transformer Visually inspect the transformer If you notice any discoloration or a smell of burnt Bakelite it should be replaced This is an indication of an internal short 2 THE VOLTMETER METHOD OF CHECKING A TRANSFORMER This quick method is employed by more experienced technicians Employ all safety precautions Turn on the power supply and set the thermostat to a point where the unit should be running Touch the two voltmeter probes to the two primary wires or terminals The meter should register a voltage reading If not power must have been interrupted before reaching the transformer and the transformer may be OK Trace the wiring back and find the break If there is power at the transformer touch the two voltmeter probes to the two secondary winding wires or terminals If you get no reading the transformer is bad and requires replacement Otherwise it is OK Since voltage going out of the transformer is proportional to the voltage going in sometimes the secondary voltage may not be high enough to activate the contactor coil Check the voltage at the primary terminal if the voltage reads lower than the required primary voltage usually printed on the transformer there is nothing wrong with the transformer Have the customer call the power company or an electrician to provide adequate voltage See the Basic Electricity section for more information about reading wiring diagrams where the t
461. sume most of the power in being activated and do not leave enough voltage for the other components with less resistance to becomeactivated eventhoughthey arestillinthe circuit See pp 186through 202 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 321 290 f 9070 WLI Tee s Overlosd Protector oO TEC o _ A Typical Schematic Wiring Traned armen Figure 188b cad Ice E hin Lini a dirus d d with its active circuits HOW IT WORKS in the ice making cycle WHEN SWITCH OPERATING ROD IS MOVED UPWARD TO ON POSITION Compressor Runs Condenser Fan Runs Water Pump Runs and Circulates Water Cutter Grid is Warm Since evaporator thermostat is not satisfied ice has not reached desired thickness it keeps the circuit closed Since current always follows the path of least resistance it will not flow through the hot gas or water inlet solenoid as each have 200 O of resistance So it goes through the thermostat with virtually no resistance See p 295 296 WHEN ICE SLAB REACHES PRESET THICKNESS THE THERMOSTAT OPENS AND THE HARVEST CYCLE BEGINS The transformer is always energized as it is connected directly to L1 and L2 It converts 115 VAC to 8 5 VAC to keep the grid warm as long as the unit is plugged in UNIT RESTARTS FREEZING CYCLE WHEN SLAB IS RELEASED FROM EVAPORATOR AND CUTTING PROCESS BEGINS Cutter Grid Remains On 322 Figure 188c Compras eet Daf jysd Prot
462. sure side service valve is usually located on the receiver and the low pressure side service valve is installed on the compressor suction inlet A quick way to determine the condition of a compressor is to check the wattage consumption of the unit A worn out compressor may be indicated by a wattage reading below its wattage rating 1 Connect the wattmeter to the compressor circuit to be measured as shown in the diagram Wires A B C and D are connected to the wattmeter in accordance with the manufacturer s instructions Depress button E At first the meter needle will fluctuate to the right then immediately it deflects to the combined reading the compressor start and run windings both engaged In a second or two the needle will deflect to the wattage consumption of the run winding The wattage readings are then compared with figures published by the manufacturer These wattage values along with a multitude of other useful CHECKING A COMPRESSOR BY information are found in a publication titled Tech Master A WATTMETER for Refrigerators and Freezers A shorted winding is indicated by a high wattage drain An open circuit is indicated by a low wattage drain Figure 33a AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 51 Bolted type serviceable semihermetic motor compressors are equipped with high and low pressure side service valves attached to the compressor housing If the compressor has to be replaced it can be isolated
463. swer TC2 CR2 or LLS On a service call for no cooling the following is observed a With the wall thermostat set on CONT or AUTO position and on its lowest temperature no motor will operate b The crankcase heater is warm What could cause this problem The T2 Transformer creating the 24 VAC circuit must have burned out Explanation when coil CR1 is not activated contact CR1 for the crankcase heater is closed What reading should be expected at T1 secondary terminals 115 VAC What reading should be expected at T2 primary terminals 115 VAC How many cooling stages are there in this unit Two How many heating stages are there in this unit None If everything works except the number one outside fan motor what electrical components are to be checked OFC1 and OFM1 What electrical components were likely to be responsible if the internal fan motor ran but the compressor the number 1 and number 2 outside fan motors did not operate with the thermostat set on AUTO COOL and lowest temperature Check CR1 If all of the fuses are good but none of the components are energized what must be checked first Circuit breaker T1 and T2 transformers What kind of motors do the compressor OFM1 OFM2 and IFM have Three phase motors because three hot wires are connected to each one of them AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 341 cc High Frexzursm Zwitch To F of
464. t of water drip to the ground To help facilitate this action the unit must be tilted one fourth inch down toward the outside to allow the condensate water to flow toward the rear of the unit and drain out by gravity on the ground through a hole in the side of the pan See fig 139 Some units have a hose attached to the drain hole to better control displacement of condensate water The drain hole in the side of the drip pan and the drain tube must be cleaned regularly In this way dirt algae etc will not clog the passage causing the pan to overflow and wet the walls inside the conditioned area Figure 138 Hex Key Stand Courtesy of MALCO Products Inc Figure 138a Figure 139 A slinger fan secured by a set screw with an Allen wrench Figure 138a Long shaftAllen wrenches are recommended for both residential and commercial units because of their convenient length Figure 139 A window unit mounted on an uneven window sill The rear of the unit should be one fourth inch lower than the front for good water drainage AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 233 Air conditioner fan blades are always secured to their shaft by an Allen screw or a regular machine screw A set of long shanked Allen wrenches is a necessity for routine repair work Occasionally the fan hub develops rust between it and the shaft in which case using a rust dissolving fluid such as Screw Loose becomes necess
465. t then the unit will resume running Most refrigeration unit noises are caused by vibration tubes touching one another or some object loose ducts or air baffles and fan motors Vibration is caused mainly by a unit that is not level uneven flooring or an out of balance fan blade These noises can be eliminated by a locating the source of the noise b placing rubber blocks between tubing or carefully bending the tubing out of the way c tightening the screws on loose ducts or air baffles and or d replacing the fan blade if it is out of balance 12 13 14 15 16 17 18 19 20 21 22 23 24 25 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 105 TEST YOUR KNOWLEDGE ON TESTING COMPONENTS What type of compressors are used in wall air conditioning units p 62 On what scale is an ohmmeter set when testing a starting relay p 70 How is a three terminal starting relay used on residential units tested p 71 On what scale is an ohmmeter set when testing defrost heaters p 96 How many types of commercial thermostats are there pp 94 95 Describe the operation of termination thermostats p 87 Describe the bypass method of checking an overload protector p 81 Name four different types of starting relays p 72 What is the horsepower range of compressors that can use solid state relays p 73 Under what conditions are start relays interchangeable p 74 11 Where wou
466. t are wired in series Low Frere to interrupt the power to the compressor Control depending on which one becomes Control 1 2 satisfied first In many commercial refrigeration units a puri oF Vs bebice zi Eresnon Corer manually adjusted thermostat is installed where the temperature is to be controlled as well as a low temperature control to more accurately control the desired temperature 96 TESTING THE DEFROST HEATER One possible cause of frost buildup on the evaporator plates or fins can be a burnt defrost heater Defrost heaters are pressed into the fins adjacent parallel to the coil It is best to test them with an ohmmeter when the ohm rating of the heater is known This ohm rating is then compared with the reading registered on the meter If the difference is more than 10 the heater must be replaced If the ohm rating is not available a continuity test can do the job in the majority of cases TESTING THE DEFROST HEATER WITH AN OHMMETER 1 Disconnect the unit from the power source and remove the evaporator cover 2 Disconnect the two defrost heater terminals from their electrical circuit Set the ohmmeter on its lowest scale RX1 and zero it 4 Touch one probe to each defrost heater terminal The meter should register a continuity reading If not the defrost heater is defective and it must be replaced pa A QUICK HEATER TEST BY USING A TEST LIGHT 1 Disconne
467. t piston or diaphragm closed against the main port See fig 98b DE ENERGIZELD E F 3 D 8 B IE gt IE E r Manual Sten 9 gure 998 3 When the coil is energized the plunger is pulled into the center of the coil opening the pilot orifice Once the pilot port is opened the line pressure above the diaphragm is allowed to bleed off to the low side or outlet of the valve thus relieving the pressure on the top of the diaphragm The inlet pressure then pushes the diaphragm up and off the main valve port and holds it there allowing full flow of the fluid When the coil is de energized the plunger drops and closes the pilot orifice Pressure begins to build up above the diaphragm by means of a bleed hole in the piston diaphragm until it plus the weight of the diaphragm and spring cause it to close on the main valve port This type of solenoid valve requires a minimum pressure difference between inlet and outlet in order to operate The manual stem as shown in figure 98b is used to manually open the valve if the line current is not available or for flushing in cleanup or other service maintenance functions The two way valve which is the most common type of solenoid valve controls fluid flow in one line It has an inlet and an outlet connection This valve can be of the direct acting or pilot operated type depending on the need When the coil is de energized the two way valve is normally closed Although nor
468. t refrigerant into a charging cylinder make sure all the valves are closed on the refrigerant cylinder the charging cylinder and those on the gauges see fig 83 1 Connect the yellow center hose of the manifold gauge to the charging cylinder 2 Connect the suction blue hose to the refrigerant cylinder valve 3 Place refrigerant canister upside down and turn on its valve Then turn on the bottom valve of the charging cylinder 4 Turn onthe valve onthe compound gauge while watching the scale on the charging cylinder Keep a hand on that valve You will see the Adjust thee cylinder scie im WEN Une E ambien Terriperalurs ard Eha caret eee level of liquid refrigerant rise in of change Then pisce a hand around the the cylinder Cylinder the proper Fling point belie beginning UOP 5 Turn off the valve when the cylinder is filled to the desired level which is the amount specified on the nameplate of the unit being charged Be certain to use the scale on the charging cylinder that corresponds with the ambient temperature 6 Turn off the rest of the valves and disconnect the refrigerant tank and the charging cylinder HINT By placing a rubber band around the cylinder at the level of refrigerant you desire before filling it it will be much easier to spot the place to stop See fig 77 The valve on top of the charging cylinder is used as a pressu
469. t thermostat is wired in series with the electric heater It is clipped to the evaporator When the temperature of the evaporator rises to 50 F 10 C the defrost thermostat opens the electrical circuit to the heater to end defrosting Contacts within the defrost bimetal close at 20 F 7 C No later than thirty minutes after the beginning of the defrost cycle the timer takes the unit into the cooling cycle at which time the operation of the compressor and the evaporator fan is restored and the electrical circuit to the heater is opened Defrost bimetals play a very important role as the second component to control the defrost heater If the heater is not de energized the excessive heat can cause damage to the unit If it is not energized the unit will no longer defrost Often a bad defrost bimetal is mistaken for a bad defrost heater Condenser The compressor draws in low pressure cool refrigerant vapor from the evaporator This cool vapor is compressed squeezed and changed to hot vapor within the compressor and then forced into the condenser In the DIL COOLER LENEE condenser heat from the refrigerant is radiated into the surrounding air causing the refrigerant to return to liquid At 70 F pressure in the condenser of operating residential refrigerators and freezers ranges between 80 and 160 psi While a residential refrigeration unit is running the temperature of the condenser should feel well above room temperature w
470. t to cut off power to a solenoid valve at the condenser outlet or the condenser fan until pressure in the condenser rises to a preset level l 6 Restricted Capillary Tube or TEV Distributor and High Superheat Two probable causes of high superheat are a restriction of the liquid refrigerant flow into the evaporator due to contamination in the system or the use of an undersized valve or capillary tube If the correct size valve or capillary tube is installed replace the filter driers l 7 Excessive Load on Evaporator above Design Conditions and High Superheat A TEV is restricted to the amount of flow it can pass by the size of its orifice Therefore if the system is required to absorb more heat than it is designed to do an excessive load high superheat will occur If this happens a balance ported TEV sized for the maximum load conditions must be installed l 8 System Contamination and High Superheat The probable causes of high superheat are moisture in the system caused by condensation from moist air penetrating the system by using internally wet charging hoses or gauges or a plugged filter drier causing excessive pressure drop resulting in flash gas Generally only a single valve is needed for head pressure controlin systems upto about fifteen ton capacity because the factory assembled units have components Sized and preset for those specific systems Larger systems usually employ two adjustable pressure valves one ahead o
471. tart No Hum No power Open circuit in motor Timer or pressure contacts open Inoperative overload protector Unit Won t Start But Hums Intermittently Excessive high side pressure Inoperative compressor Bad or weak start capacitor Wired incorrectly Open stator wiring blows fuse Low line voltage Start winding open or shorted Relay contacts not closing Check fuses circuit breakers lines Replace motor or hermetic unit Check timer controls and pressures Check and replace if necessary Eliminate cause or wait for pressure to drop Check for closed valves Check and replace if necessary Replace capacitor Check wiring diagram rewire Check leads If OK replace compressor Check for voltage drop Check leads If OK replace compressor Operate manually Replace relay if defective Compressor Starts But Start Winding Does Not Disengage Start or run winding bad Run capacitor inoperative Compressor binding Excessive high side pressure Bad start capacitor Low line voltage Inoperative relay Improper wiring Compressor Runs But Short Cycles Low line voltage Excessive high side pressure Excessive low side pressure Weak overload protector Defective run capacitor Defective discharge valve Compressor binding Insufficient motor cooling Check resistance Replace compressor if start or run winding faulty Check and replace if necessary Check for worn bearings low oil
472. tart compressor motor is a popular type of hermetic motor in refrigeration units A capacitor is installed in series with the motor start winding to produce more starting torque by providing more initial voltage This capacitor is isolated from the Protec Lew circuit during the run cycle see fig 43 This type of compressor is normally used in walk in coolers salad bars beverage coolers ice machines and similar commercial refrigeration units Capacitor start capacitor run compressor motor is a very efficient type of motor A start capacitor increases its starting torque and a run capacitor increases its efficiency during the run cycle It is used in commercial refrigeration for heavier applications such as larger walk in coolers heavier air conditioners etc Figure 44 illustrates how they are wired Permanent split capacitor run compressor motor This type halle dea read iai of hermetic compressor motor is widely used in wall or window type air conditioners Deria Protec par It is not equipped with a start capacitor Its starting torque is almost low Consequently it is sensitive to the fluctuation of Thernastat the line voltage Supply voltage z should not exceed 10 of the required voltage printed on the compressor nameplate A run capacitor is installed between its start and run windings to provide more efficiency during the run cycle Figure 45 shows a typical wiring diagram of these motor Typical
473. tat adjusting knob in the unit cabinet Remove plastic cover and component out far enough for inspection of charred or disconnected terminals If it looks OK and without letting terminals touch anywhere else Fasten the two jumper wire clips to the two terminals Turn on the power a If the unit starts running replace the thermostat b If unit remains dead proceed Connect the two test wire clips to the two terminals on the overload protector Plug the unit into the power supply a If the unit starts running replace the overload protector b If it doesn t start proceed Check circuit breaker Flip breaker to ON position if open Check fuse box for a burnt fuse as described in figure 152f Remove every wire from the compressor terminals Connectthethree test cord clips see fig 35 tothe three compressor terminals Wire marked S to compressor terminal S R to Rand C to Connect power to the unit Depress the button on the test cord momentarily and release it If compressor starts and continues running replace starting relay If compressor does not start replace compressor If compressor starts but stops when test cord button is released replace compressor You can use a hard start kit fig 45a instead of a test cord It can be used on compressors that operate with or without start capacitors to provide sufficient voltage This is a good tool to use on compressors that no longer run du
474. ted from the compressor discharge line and out the line disconnected from n 10 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 175 REPLACING A BOLTED TYPE COMPRESSOR Turn the valve stems on both the high and low pressure sides all the way clockwise to seal off the refrigerant in the commercial system Remove the bolts connecting both service valves to the compressor and unbolt the compressor from the chassis Disconnect power detach wires and remove the compressor Install the new compressor by reconnecting both service valves and the wires to the proper terminals in the new unit The new compressor comes with new gaskets to be placed on the compressor high and low side connections after you have moistened them with a little compressor oil In these cases the refrigerant does not have to be discharged from the system Turnthe high and low pressure service valve stems all the way counterclockwise to restore refrigerant circulation see figs 102 120 and 121 the filter drier Do this for at least twenty seconds for average size units to clean the high side of the system by forcing the contaminated oil out of the system Many condensers have a strainer in their last pass This strainer must be removed before flushing The new drier has a strainer which will take its place See fig 142 Disconnect the capillary tube from the evaporator and flush the evaporator with CO or Nitrogen gas for at least
475. termination thermostat is mounted on the evaporator outlet It returns the system to the refrigerating cycle when the ice on the evaporator is defrosted and it senses an adequate rise in the evaporator temperature Liswid Lise Eclser Valve Je y anlampid Valve 2 Shave Defrost Eelbssejd Value Unit Ini Defrost Cycle AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 319 Starting Relay Dunricad Heating liben nl SCHEMATIC WIRING DIAGRAM OF A COMBINATION WATER COOLER AND WATER HEATER Figure 187a wer luas Protec bar ane ai Haing Treregs tat Gates Haabirg Elemani k The unit is cooling water Figure 187b Schematic Wiring Diagram of a Combination Water Cooler and Water Heater The cooling and heating operations of the water dispenser are independent of each other When the cooling thermostat is satisfied the unit will no longer cool When the heating thermostat is satisfied the unit will stop heating the water until the water temperature drops to a predetermined point See pages 203 through 206 Line De Eusrgirsd m Lima Ezargiraed parimi Probector Domnas Pan Robot 01 uter haating The unit is heating water Figure 187c 320 TIS Compressor Overload Protector Relay Fan Matar 50 Ohi Evaporaber
476. the case of units that have a fan cooled condenser be sure nothing is blocking air circulation at the bottom and in the front of the unit For units with their condenser in the back a wall clearance of at least two and a half inches is required for proper air circulation Make certain that adequate clearance is provided on top and bottom as well as all sides see fig 75 Refrigeration units should be carefully leveled at the time of installation This is probably the only time the level is checked Most units now have built in leveling feet that screw in or out of the base to level each corner Also rollers or small dollies are available if the unit is to be moved around Small shims of wood or other material may be placed under the feet of the unit to be leveled It is important to do this adjustment with a spirit level such as the ones carpenters use Small metal ones three or four inches long are available and can be carried easily in a toolbox Since hermetic compressors used in residential refrigerators and freezers do not produce sufficient starting torque to overcome a high head pressure if the unit is stopped and immediately restarted it will not resume running until the head pressure in the system drops by equalization of gas pressure through the capillary tube This delay in starting does not mean there is something wrong Wait for a few minutes until the head pressure drops low enough for the compressor to overcome i
477. the common method of checking the door seal p 100 What color wire is connected to the compressor starting terminal in a Frigidaire refrigerator pp 59 60 Can a liquid line filter drier be installed on the suction line p 108 Explain the method of replacing thermostats in residential refrigerators p 92 What minimum clearance should be maintained on top of a freezer p 104 Which timer terminal is responsible for the defrost cycle in a Gibson refrigerator p 79 Can a motor compressor rated at 115 VAC operate on 99 VAC pp 52 53 How can unmarked compressor terminals be identified p 58 59 Are permanent split capacitor run motor compressors used in residential freezers p 62 What is the purpose of the heating element used in the charging cylinder pp 110 111 What is the purpose of wrapping a filter drier with a wet rag at the time of silver brazing pp 108 109 Can the motor in a commercial timer operate on 24 VAC p 78 Explain the testing procedure for an overload protector using the bypass method p 81 Can a compressor short cycling occur due to a bad light switch p 98 Why is it sometimes necessary to wrap the wire around the jaw of a clamp on ammeter p 97 What compressor terminal is located on the bottom right in a Norge refrigerator pp 58 59 What is the main reason for a compressor efficiency test p 67 Can a solid state relay be installed on a compressor used in a residential refrig
478. the compressor start terminal The ohmmeter should show an open circuit reading on the RX1 scale otherwise the relay is defective Touch one probe to the relay terminal on the outside and the other probe to the relay terminal that connects to the compressor start terminal The ohmmeter should register an open circuit Otherwise the relay is bad See fig 46a Now turn the starting relay upside down and touch one probe to the relay terminal that is connected to the compressor run terminal and the other one to the relay terminal that connects to the compressor start terminal The meter should register a zero reading on the ohmmeter Otherwise replace the relay Testing Magnetic Relays with Two Terminals r 2 Figure 46 Terminal Positions Current Magnetic Relay with Three Terminals Figure 46a 72 STARTING RELAYS Starting relays in commercial units unlike residential types are not always fastened directly to the compressor terminals They are usually installed in a box next to the capacitors and are wired to the compressor terminals See fig 151 The relays shown in figure 47 are connected directly to the compressor terminals There are four types of relays Figure 47 Current Type Push On Style Starting Relay Current magnetic relay Potential voltage relay Thermal relay Solid state relay pem Figure 47a 1 Current magnetic relays The compressor draws up to 60096 mo
479. the particular component s which is are activated by that contact becomes inoperative while the rest of the unit works 2 Unlike solid state relays the operation of a contactor depends magnetic field created by a coil when it becomes energized When this magnetic field is created the points are drawn together closing circuits to energize certain components To determine if the contactor is the problem when a unit becomes inoperative which in many cases it is find the condensing unit where the compressor is located and remove its side panel There is a junction box where the main power lines come into the condensing unit The contactor is usually installed inside that box figs 152c and 152d With the wall thermostat inside the building turned on watch the contactor to see if the points close If not touch the two probes of a voltmeter to the two wires connected to the coil terminals to check for proper voltage If power reaches there but the points are not pulled together or if it pulls for a short while and then releases the contactor must be replaced If the meter registers no reading at the coil terminals the wall thermostat and the transformer will have to be checked as either one could cause an interruption of power to the coil terminals If the contactor hums but does not pull it may mean either insufficient voltage is reaching the coil terminals or the coil is bad Check the voltage as outlined above If the meter reg
480. the two terminals on the overload protector Be careful not to allow the clips to touch any other object Be sure the insulating covers on the clips completely enclose them See fig 56a 3 Reconnect the power for a short time Be careful not to touch any part of the unit as there is always the danger of a shock hazard 4 f the compressor motor starts running without drawing an unusual amount of amperage this can be checked by a clamp on ammeter clamped around the wire supplying Figure 56b power to the overload protector the overload protector is defective and will need replacing 5 Disconnect the power supply disconnect the test wire and replace the overload protector Figure 56a The bypass method of checking an overload protector Run this test very briefly Check the amperage The dotted lines show proper insulation coverage for a pair of alligator clips 82 TESTING THE CONDENSER FAN MOTOR Condenser fan motors are used to A CONDENSER FAN USED IN circulate air through the condenser to cool COMMERCIAL AND RESIDENTIAL it They are located next to the condenser in fan forced condenser types behind the compressor compartment cover See fig 56c and 57 1 Remove the rear lower access cover with the unit running to determine if the fan is working 2 If not disconnect the power supply When replacement is necessary the watt 3 Remove the two condenser fan rating and revolution per minute of the mot
481. ting recharging and installing a new filter drier In most belt driven compressors see figs 31 and 32 these valves are also mounted directly on the high and low side ports of the compressor To gain access to the system 1 remove each valve stem cap and each gauge line access cap 2 connect the compound gauge to the low side valve and the high pressure gauge to the high side valve and pur ar t jon in Lem Cenar hia o Hugtion Lire Conner Ludi Figure 101 RECEIVER SERVICE VALVE Liquid Line Cormac Lon Gauge Connect ton RECEIVER Valve stas Pachimng Hut Gland awyu Connect ibn Figure 102 VALVE STEM POSITIONS Courtesy of Tecumseh Products Company 3 usinga service wrench turn the valve stems to open the lines to the gauges 156 In figure 102 you see the different positions of the stem When the stem is all the way in the condenser or suction line is blocked depending on whether the valve is installed on the suction or discharge line When the stem is turned counterclockwise all the way out the gauge connection is blocked This is the position it must be in when disconnecting the gauges When the stem is in its midposition the path is opened to the suction or discharge line and to the gauge manifold as well as the compressor So then every port is open When the stem is all the way in it clos
482. tion Appliance and the temperature of the coil drops Spesiaky Cartrals Division AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 159 the refrigerant in the bulb contracts and reduces pressure on the diaphragm which closes the valve The valve is spring loaded so the spring tension and the pressure in the evaporator also work to shut off the valve These three forces control the performance of the thermostatic expansion valves See figs 110a and 110b Force F1 is applied to the valve diaphragm by the expansion of the refrigerant in the sensing bulb which tends to open the valve F2 is the force applied by the evaporator pressure which tends to close the valve is the spring tension which acts to close the valve UOISIAIG 51023000 Ajer2ads pue adueljddy uoje3 Asayinop Figure 108 If force F1 is greater than forces F2 and F3 the valve will open If Nn ee forces F2 and F3 are greater than ed AX iiaia F1 the valve will close Liquid Bacmiwar Both the temperature perceived by the sensing bulb as well as the pressure inside the evaporator work together to control the flow of refrigerant and consequently ONSIDE the temperature of the unit Figure 109 FLOAT SYSTEM On the bottom of most TEV valves there is an adjusting stem To gain access to the stem first remove the seal cap covering the stem Use a service wrench to turn the stem clockwise to decrease the flow
483. tion temperature determined in Step B from the suction gas temperature measured in Step C The difference is the operating superheat See fig 110h For best results there are two types of TEV on the market today 1 internally equalized TEV used in regular evaporators where pressure drop inside the evaporator is not significant and 2 externally equalized TEV see fig 110h used on the evaporators in which pressure drop is considerably high The pressure inside the sensing bulb is the only opening force in the valve working against the closing forces of the spring and evaporator pressure When the pressure drop at the evaporator outlet where the bulb is installed is substantial this reduced pressure low temperature reduces the opening force applied to the valve diaphragm and the valve tends to close and starve the evaporator To normalize this condition it only makes sense to reduce the closing force evaporator pressure applied to the diaphragm This is done by connecting the evaporator outlet reduced pressures to the valve by a tube This allows the low pressures from the evaporator outlet where the opening force is also affected to reduce the excessively high pressures that tend to close the valve Figure Lion An extrae ipai TEY pomor a ba Feia at T CINE cmd inis bry um Lomari t lerep T C qi rea Line mumi 17 in r
484. tly to its own separate evaporator outlet to ensure proper operational response of each one See illustration in sec 11 5 Replace condensing water regulator Clean blockage or replace equalizer line Normal for fan cycling operation In order to eliminate base fan cycling on ambient air temperature with pressure override or use variable fan speed or flooded head pressure control system but not both together See section 1 9 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 379 Probable Cause Remedy Faulty or oversized evaporator pressure i Repair or replace and install EPR valve regulator EPR valve Compressors cycling in multicompressor system Applies to water cooled condensers This is normal MISCELLANEOUS PROBLEMS V 1 Compressor Starts but Motor Cycles Off on Overload Protector Probable Cause Excessive suction pressure Excessive discharge pressure Tight bearings or mechanical damage in the compressor Low line voltage Improperly wired Defective run capacitor or relays Defective overload protector Shorted or grounded motor winding V 2 Unit Starts but Short Cycles Probable Cause a High pressure lock out Dirty condenser Excessive refrigerant charge on nonreceiver system High suction pressure See sec IV 1 High low voltage high amperage on three phase supply voltage out of balance Voltage should not vary more than 3 between lines Low pressure lock out
485. to become energized and melt the frost accumulated on EE A BE the evaporator by producing the necessary i heat It stays energized until the evaporator reaches a temperature of about 50 F 10 C At this point a termination bimetal senses the rise in temperature and disrupts the flow of current to the defrost heater even before the defrost cycle ends In many models a length of electrical resistance heating element is also installed on the inlet of the drainpipe It is energized during the defrost cycle to prevent condensation from the evaporator from freezing and blocking the flow down the drain tube In cycle defrost refrigerators an electric resistant heating element wired in series with the compressor is clipped to the inlet and outlet tubing of the fresh food evaporator to defrost the frozen food evaporator during the off cycles see fig 5 The heater is energized when the temperature control is satisfied Evaporator fan In frost free refrigerators and freezers a fan is installed over the evaporator to move air through the evaporator and circulate it in the freezer and the fresh food compartments If this fan fails to operate there will not be enough air velocity for an effective heat exchange to AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 33 prevent a frost buildup A The pattern of air on the evaporator coil circulation through C tly f t will the condenser onsequently Trost WI Acondenserfanmotor
486. to properly cool the condenser Refrigeration is unaffected but a typical complaint is a higher than normal water bill THREE POSSIBLE CAUSES OF EXCESSIVE WATER FLOW Water valve adjusted for a higher flow Readjust the valve b Water supply pressure too high Rarely happens Leaky water valve as evidenced by a continuous flow of water when the unit is turned off Replace the valve 390 Figure 214a See recommended valve opening 1 Yaire pressures psi on mpm page 364 iz turn at tima CROSS SECTION OF A WATER REGULATING VALVE See fig 214b If the maximum desired water temperature is 65 F the valve must be adjusted to open at 74 psi for systems using R 12 123 psi for systems using R 22 etc HOW A WATER REGULATING VALVE WORKS High side pressure actuates bellows which move the valve slide across the seat A rise in high side pressure opens the valve while a drop in high side pressure will close the valve Adjustment is simple because the adjusting stem is completely accessible Figure 214 A WATER REGULATING VALVE s oJ3u0 Ayeioeds pue adueljddy uorjejodjo uoie3 Ase1no5 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 391 WATER REGULATING VALVE INSTALLATION TIPS A water regulating valve is installed in the condenser water inlet or outlet line with the head pressure connection attached directly to the high pressure side of the system The valve may b
487. to the unit and isolate the component from the rest of the circuit by disconnecting its terminals from all other wiring The current necessary to operate the meter is supplied by a dry cell battery within the meter The ohmmeter is used to check the continuity or the resistance of a circuit ora load in a circuit Continuity means a continuous uninterrupted circuit Today however the pocket size digital multimeters capable of reading volts and ohms and in some models amperes are becoming increasingly popular because of their convenience and accuracy Rather than a specific scale with an indicator needle digital meters produce a direct number reading like a calculator Unlike the conventional meter that registers O O for a continuous path the multimeter is extremely sensitive and displays the actual ohm value of the path being measured 298 The meter probes must not touch anything other than the part or section being tested to prevent an erroneous reading The reason for isolating the component to be tested is that if it is left in the circuit the reading registered will be erroneous as the resistances of every component in that circuit will be included When the needle of a conventional ohmmeter points to 0 continuity in the circuit being checked is indicated When it points to a specific ohm reading the amount of resistance in that circuit is indicated When the needle points to the infinity symbol it indicates an interruption
488. tor cover must be removed to gain access to it To do this remove all food from the freezer compartment all the shelves and if it has one the automatic ice maker Then remove the shelf studs and their screws Next remove the screws holding the evaporator cover to the back of the liner and carefully remove the evaporator cover Most service technicians prefer to use a heat gun for rapid defrosting of freezers and coils rather than the hot water spray method which generates an excessive amount of drain water These guns operate similar to a HEAT GUR hair drier except for their temperatures that are considerably higher between 350 F and 750 F with high velocity air They are also used to apply shrink tubing for insulation drying out moisture in hard to reach places loosening rusted nuts and bolts speed drying paint and bending tubing Figure 63 Courtesy of Robinair Division SPX Corporation AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 87 HOW TEST THE DEFROST THERMOSTAT TERMINATION SWITCH WITH AN OHMMETER The termination thermostat is clipped to the evaporator When the evaporator temperature rises to about 50 F the contacts within the thermostat open causing the defrost heater to become de energized When the evaporator temperature drops to about 20 F the contacts within the thermostat close and the defrost heater becomes energized when the unit is in the defrost mode Buy a small container of CO a
489. tor system requiring different temperatures such as one evaporator in a frozen food display with an average temperature of 20 F and another in a walk in cooler set at 40 F Since in this system the two evaporators cannot be the same temperature a reducer valve two temperature valve is installed at the outlet of the warmer evaporator to increase the pressure inside the warmer evaporator by reducing the constant suction force that the compressor applies to it Also a check valve is placed at the outlet of the colder evaporator to stop the back flow of refrigerant thus preventing the buildup of more pressure and consequent warm up of the colder evaporator during the off cycle See figs 96 and 95 They are manufactured with different physical appearances i j VALEB ams ITS STALL TWO DIFFERENT STYLES OF TWO TEMPERATURE VALVES TWO DIFFERENT TYPES OF CHECK VALVES Figure 95a Courtesy of Henry Valve Co INSTALLATION OFA SURGE TANK Figure 96 Courtesy of Eaton Corporation Controls Division Figure 95 There are two general categories of two temperature valves those using a spring inside their mechanism including spring valves with thermostats or solenoids and valves employing a sensing bulb very much like TEVs Operation ofthe spring type valve is quite simple When the pressure inside the evaporator goes up due to evaporating refrigerant the spring opens the valve to allow refrigerant to flow out of th
490. tray A drip man condensing unit An assemblage of refrigerating components that change vapor refrigerant to liquid refrigerant usually consisting of the compressor condenser condenser fan and a receiver tank It could be roof or ground mounted condenser fan A fan located near the condenser to move the air rapidly over the surface of the condenser coil to aid in the transfer of heat cold control Another name for a thermostat compound gauge refrigeration A device capable of measuring pressures that are above or below atmospheric pressure AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 421 condensation The process by which moisture in the air forms droplets of water when coming in contact with a cold surface conductor A body through which heat or current is transmitted convection As air is cooled it becomes heavier and tends to seek the lower levels As it becomes warmer it gets lighter and tends to rise thus creating air circulation capacitor A device for storing an electrical charge de energize To stop current flow through a circuit defrost bimetal A temperature sensing device installed on the evaporator coil to stop current flow to the defrost heater when frost on the coil has melted Most commercial units employ a sensing bulb for this purpose defrost cycle One of the refrigerating cycles in which the accumulation of ice on the evaporator coil is defrosted In this cycle sometimes the compressor is
491. treatment authorities Clean evaporator plate with correct cleaning chemicals Check valve and replace if necessary Replace ice thickness control Readjust ice thickness control 200 Problem and Possible Cause Ice Slab Builds Up Unevenly on Evaporator Plate Unit running on low charge Moisture in sealed system Faulty expansion valve Water distribution pipe does not distribute water evenly over evaporator plate Empty Water Tank Clogged water inlet screen Defective evaporator thermostat No power to water solenoid Faulty water solenoid valve Restriction in water line In newly installed smaller units 50 Ibs water solenoid valves are not energized until the first defrost cycle Locate leak replace drier evacuate and recharge Look for possible leak repair as required Replace expansion valve if necessary Clean holes in distribution pipe and repair or replace water float if water is too low in reservoir Remove and clean screen Replace thermostat Check electrical diagram locate disconnection and repair Replace solenoid valve coil Clean restriction from lines and water shut off valves Wait for the first defrost cycle No Ice Built Up on Evaporator Plate in 100 200 and 400 Ib units Defrost solenoid valve stuck open Faulty water pump Faulty float valve Master switch in Clean position Some models Grid relay stuck on Defrost Faulty ice thicknes
492. ts probe is near a source of a refrigerant leak liquid line The tube connecting the condenser or receiver to the capillary tube or any other refrigerant control TEV or AEV load The work required of the system The amount of cooling necessary to accomplish the desired results loading The period in which the TEV permits the refrigerant to flow into the evaporator low side float control A control mechanism that maintains a constant level of liquid refrigerant in the low pressure side of a refrigerating unit 426 low side pressure Pressure in the compressor suction line and the evaporator low side pressure control low pressure cut out switch A switch connected to the compressor that limits the low side pressure of a refrigerating unit mercury type thermostat An electrical switch that controls the temperature by the expansion or contraction of mercury as it is affected by heat or cold moisture Water in the system caused by leakage of outside air motor compressor The mechanism creating the pressure difference in the sealed system off cycle That part of the refrigeration cycle in which the compressor does not run open circuit Interrupted electrical path preventing current flow overload Current above the capacity of the mechanism overload protector A device placed in series with the common terminal of the compressor It shuts off power to the compressor upon sensing above normal amperage It reconnects power to the
493. turned off and the defrost heaters turned on and sometimes a solenoid valve bypasses not gas to the evaporator with the compressor running dehumidifier A device to remove moisture from the air distributor refrigeration An apparatus having a single inlet port and more than one outlet for directing the flow of refrigerant into multiple ports of a condenser or an evaporator s drier filter drier dehydrator A device to remove moisture from refrigerant circulating in a sealed system defrost timer An apparatus that causes refrigeration cycles to change See defrost cycle above defrost heater The heating element placed around or adjacent to the evaporator coils During the defrost cycle it melts the ice built up during the cooling cycle duct work Channel s through which air flows 422 differential The pressure difference between the cut in and cut out pressures in a pressure control switch energize To connect power to an electrical component electrical circuit The complete path of electrical current electromagnet A device creating a magnetic field when energized electromotive force Electrical energy that induces current flow in an electrical circuit which is measured in volts epoxy A substance characterized by great adhesiveness and strength Can be used to seal small evaporator leaks equalizer line Auxiliary tubing linking the evaporator outlet to the TEV to exert an average true pressure on the valve di
494. ty of an air conditioner is measured by the British thermal unit Btu A Btu is the amount of heat required to raise the temperature of 1 Ib of water 1 F AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 227 When an air conditioning unit is rated at 10 000 Btu it means that it is capable of removing 10 000 Btu every hour The larger the Btu capacity the bigger the area the unit is capable of heating or cooling Usually a unit is rated by its tonnage 12 000 Btu are equal to 1 ton The tonnage can be calculated by dividing the Btu rating on the nameplate by 12 000 If the nameplate indicates that the unit is rated at 24 000 Btu dividing the 24 000 by 12 000 will determine the tonnage corresponding to the indicated Btu which will equal to 2 tons A 4000 Btu unit will be equal to four twelfths of a ton or one third ton A frequently used term is energy efficiency ratio or EER The ratio of Btu to the wattage rating of the unit is referred to as the energy efficiency ratio This indicates the cooling or heating capability of the unit as compared with the electricity it uses Btu divided by watts equals EER The higher the ratio the more efficient the unit Today air conditioning units have an energy efficiency ratios of up to twenty seven these are the more sophisticated ones with variable speed fans and more energy efficient motors LATENT HEAT AND THE THEORY OF CHANGE OF STATE To vaporize water it must be brought to a boil which
495. ucet partially closed Bad water pressure regulator Clogged water valve inlet screen cool Leave wire connected to compressor common terminal Disconnect the relay connection to the compressor run winding Connect a wire between compressor run terminal and the line that brings current to the run terminal of the relay Plug in the unit Momentarily short between the compressor run and start terminals If compressor starts relay needs to be replaced Clean condenser Check condenser and fan blade Clear restriction or repair or replace fan blade Check and tighten connections Replace compressor Customer should contact local water company or plumber Repair or replace valve Open faucet all the way If pressure is adequate replace regulator Clean or replace screen Water Does Not Come Out of Push Button Water Valve Faulty water dispensing valve No water supply in building Water inlet valve screen completely restricted by minerals Restricted water pressure regulator Inlet water line kinked or restricted by minerals in water Repair or replace valve Advise customer to call local water company Check valve screen and clean or replace as necessary Repair or replace regulator Straighten or repair pipe or use a factory recommended chemical to clear line Substantial experience has proven that Lime Away is an excellent product to do this job If this or any other similar product is used to dissolve
496. uit What is the voltage in the line voltage circuit 230 VAC On a hot summer day a central air conditioner is not cooling With the controls on the wall thermostat set on AUTO COOL and the lowest temperature setting the following is observed the compressor runs for about three minutes stops for about three minutes and the condenser fan is not operating What electrical components should be checked The control relay contact and condenser fan motor In answering a no cooling complaint the following is observed when the thermostat is adjusted to its coolest setting AUTO and COOL only the Indoor fan motor starts operating but the compressor and the condenser fan do not What component s should be checked The low pressure control cut off and the control relay coil After adjusting the wall thermostat to COOL AUTO and its lowest temperature setting nothing worked Upon turning the thermostat 14 15 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 335 control from AUTO to ON the indoor fan starts running but nothing else works What conclusion can be drawn and what component s may be defective It may be concluded that the wall thermostat is defective check the COOL switch and the mercury switch and refer to page 236 Testing a Wall Thermostat Replace the wall thermostat if necessary In answering a no cooling complaint for a central air conditioner and after setting the wall thermostat contro
497. umps using expansion valves are required to have check valves installed In locations with severe weather the outside coil is placed underground because the temperature there is higher in the winter and lower in the summer They are referred to as ground coils Some units use circulating water as a heat absorbing agent to cool the outside coil when the unit isin the cooling mode When the unit is in the heating mode circulating water is a good method to give up its stored heat to the outside coil See figs 104 and 105 HEAT PUMP IN THE COOLING CYCLE Whenthereversing valveis energized amagnetic field is created inside the reversing valve coil causing the armature to lift or slide opening one port and closing the other one This connects the inside coil to the compressor suction line changing it to an evaporator and the outside coil to the compressor discharge line enabling the unit to cool Thus the unit becomes a regular air conditioning unit Eapanxbzr Deve Check Valve filter Drier Chesh ron m Si pare oi Deslca HEAT PUMP IN COOLING MODE Locum late 3 Cieck Valera check Vales piter Prise r 1 Way i il 1 Ea REL DI Darjan Dav ip HEAT PUMP IN HEATING MODE i Figure 174 gt Note the direction of flow of refrigerant in cooling and heating modes Only two directional driers can be used in
498. ure R 12 and R 500 refrigeration systems can be retrofitted to use MP 66 TIF H 10A HALOGEN LEAK DETECTOR Used for HFC CFC or HCFC 9450 VACUUM INDICATOR refrigerants Digital Micron Gauge It instantly recognizes vacuum increase or decrease moisture present and leaks in the system Figure 218 Figure 219 Courtesy of TIF Instruments Inc 404 SUVA MP 39 REFRIGERANT This is the recommended environmentally acceptable alternative refrigerant for medium temperature R 12 system evaporators operating at 10 F 23 C or higher such as food and dairy display cases beverage dispensers walk in coolers residential and commercial refrigerators and beverage vending machines This refrigerant comes in 30 Ib 120 Ib and 1700 Ib containers color coded coral red Nylon hose is recommended for use with SUVA MP 39 refrigerant Existing R 12 refrigeration systems can be retrofitted to use this refrigerant Urge STEP BY STEP RETROFIT INSTRUCTIONS FOR SUVA MP 66 AND MP 39 Remove the R 12 or R 500 charge from the unit 15 inHg vacuum is required to remove the charge Drain the existing oil from the compressor unless alkylbenzene lubricant is already in the system Small hermetic compressors which have no oil drain must be removed from the system in order to drain the existing oil through their suction line In larger systems oil must also be removed from low spots around the evaporator All the existing lubricant in the oil
499. ure of the circulating oil mixed with refrigerant leaving the compressor discharge valve rises to 350 F 177 C it will break down and form hydrochloric and hydrofluoric acid sludge and varnish The acid will corrode the insulation on the motor windings and increase the operating temperature of the compressor motor Shortly after this happens the motor windings will short circuit and burn out Acompressor burnout is indicated by oil color changing from clear to black depending on the severity of burnout and by a very unpleasant pungent odor Oil test kits available from refrigeration supply houses can be used to determine the degree of contamination The test is simple and instructions are supplied with the kit Because compressors are burnt out more frequently by above normal temperatures caused by high head pressure condensers should therefore be checked and cleaned on a regular basis Condenser fins can be cleaned with a long bristle brush and or high pressure gas such as nitrogen air or carbon dioxide PROCEDURE FOR REPLACING A BURNT OUT COMPRESSOR CAUTION Do not touch the oil from a burnt out compressor as the acid will cause a burn Always wear rubber gloves Also safety goggles will protect the eyes when discharging a system 1 Remove the filter drier Remove the compressor 3 Flush the condenser with Nitrogen or CO gas To do this purge the system by forcing Carbon Dioxide or Nitrogen gas from the line disconnec
500. ures but refer to pages 257 and 263 to bypass the correct thermostat wires in steps E and N Check for bad blower fan Check for bad blower capacitor see p 91 fig 66a Check for bad blower relay Replace any of above as necessary Check for bad wall thermostats as in E E Unplug air handler Disconnect red and green wires from wall thermostat terminals and connect together Reconnect air handler to power If blower fan stars replace bad wall thermostat Use all personal safety precautions before conducting those tests The use of a voltmeter is necessary in performing these tests see pp 298 and 299 AN ELECTRICAL DIAGNOSTIC CHART FOR A SPLIT SYSTEM CENTRAL AIR CONDITIONER IN THE COOLING MODE Setthe Wall Thermostat on COOL ON position and on the lowest temperature setting Unit starts operating and cooling Only the evaporator blower starts blowing Only the condensing unit starts running Nothing happens F Checkfor an unplugged air handler cable bad fuse or tripped breaker for that plug Check for a bad transformer see p 242 and replace if necessary Check for a broken wire or a loose or disconnected terminal in the low voltage circuit and repair as necessary Check for a bad wall thermostat see p 263 and replace if necessary N Check for a bad mini pressure control see p 248 replace if necessary Check for a bad thermostat and replace if necessary 1 Unplug the air handl
501. uses the ice to melt and gradually evaporate after about forty eight hours A heat gun Fig 63 or a regular hair drier may also be used to more quickly serve the same purpose The puncture may then be sealed by brazing or by sealing it with the same epoxy used for repairing evaporators Fiberglas kits available from the supplier can also be used Make sure the unit is moved to a place away from the extreme cold and humid ambient air during this procedure WATER LEAKS INSIDE THE CABINET The moisture drain tube to the water evaporator pan may become plugged with debris and gummy substances When that happens water created in the defrost cycle cannot drain out It overflows and leaks down covering the freezer floor and then during the refrigeration cycle it turns to ice To remedy the problem unplug the unit and let it defrost Clear the drain line of debris by shooting a stream of air into it or simply by blowing into it A similar thing happens if the unit is not seated level and does not allow the drain water to reach the opening of the drain tube In that case the water accumulates to the point that it overflows and runs down the insides of the walls misses the drain pan and forms a puddle under the unit See fig 3 Most models come with a heating element around the top of the drain tube If that element stops working ice will form in the opening and cause one or more of the symptoms mentioned above Test the heating element with
502. ush you will find a blanket of lint covering the inside of the coil see fig 165 i AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 241 Central air conditioners generally use capacitor start capacitor run compressor motors see fig 44 unless a three phase compressor motor is used see fig 178 TRANSFORMERS A transformer is used when there is a need to increase or decrease voltage in an electrical circuit There are two sets of windings see figs 150 and 150a ina transformer which are referred to as the primary and the secondary windings Figure 150 Primary Coneee bani cpncmep srEimeg Agg LpA qo ie Detarminge Ube poser wepply ceonhnact appropriate primary wire Ec Lha power am indicabaed by bee color coding tn get the 24 volte af When the primary winding is connected to the available power supply witha particular voltage the secondary winding generates current with a higher or lower voltage depending on the number of times the wire is wound as well as the size of the wire used in the winding If the number of windings of the primary winding is larger than that of the secondary s the secondary winding produces a lower voltage and it is referred to as a step down transformer For example converting 110 VAC to 24 VAC If the number of windings in the secondary winding is greater than the number in the primary winding a higher voltage is produced from the seco
503. ust be replaced If the low side pressure checks abnormally low find the cause remedy the problem and place the control back in the circuit as it most probably is good The same checking procedure is applied to a high pressure mini control with the difference that the high side pressure must be checked OBSERVE ALL THE PERSONAL SAFETY MEASURES Figure 155 A Mini Pressure Switch Courtesy of Johnson Controls HOW A MINI PRESSURE CONTROL WORKS In figures 154 and 155 the 24 volt current magnetizes the contactor coil causing it to make contact between A and C and B and D The current flows in the circuit through A to C m b D back to B and then it flows to the neutral side of the line If the pressure in the discharge line falls below a predetermined point the mini pressure control disconnects the low voltage line to the contactor stopping the compressor and the condenser fan motor s A defective mini pressure switch can shut down the system FT Wall Litem Lc Pian Lire m 2 2071700 1 1 ie IAC hine Loew Bucticn j ini Fressurr li ios C LE i a Mart Ciparitcr A typical installation of a mini pressure control in a central air conditioning unit Figure 154 AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 249 CENTRAL AIR CONDITIONERS SPLIT REMOTE SYSTEMS OPN Condensing unit Service valves Suction li
504. ust be replaced prior to evacuating the system with a vacuum pump and recharging the unit with refrigerant The drier should be installed as close to the capillary tube as possible Always keep the drier sealed until installed If left open it will absorb moisture from the air and very soon become saturated In a properly operating system the filter drier should feel slightly warmer to the touch than the ambient temperature Tubing These are the pipes through which refrigerant is circulated throughout the system The tubing used in household units is made of copper Aluminum and steel are seldom used Copper is relatively 9 soft flexible and easy to bend and flare The nine most common sizes in use are 3 16 A DEFROST BIMETAL 1 4 5 16 3 8 7 16 1 2 9 16 5 8 and 3 4 outside diameter OD Handle the tubing with care to prevent damage Defrost bimetal Also known as a termination switch or defrost thermostat Not to be confused with the cold control thermostat discussed earlier In frost free refrigerators and freezers every six eight or twelve hours depending on the type of defrost timer being used a timer de energizes the compressor and the evaporator fan and at the same time energizes an electric AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 29 resistance heater which is clipped to the underside of the evaporator fin area to defrost the evaporator for no longer than thirty minutes A defros
505. ve too many fittings All three cause excessive liquid line pressure drop Replace piping sections with the correct line size l 4 Inadequate Subcooling and High Superheat If the system is designed to provide a certain degree of subcooling to compensate for system pressure loses and the liquid refrigerant is inadequately subscooled flash gas at the TEV will occur You will need to increase the subcooling for proper system performance A heat exchanger with an increased cooling capacity or an increase in condenser fan speed may be needed Clean linted condenser fins See fig 198 l 5 Low Head Pressure and High Superheat All air cooled condensing units are sized for a specific ambient air temperature usually 90 F 95 F When ambient temperature drops 10 F of subcooling is enough for up to below 50 F the condenser twenty five feet of elevation becomes oversized and some type of head pressure control Figure 198 is needed A variable speed Brass lisse amp lial Rap of mertios Exrtarnai fan is no longer effective due IL to low ambient temperatures and or prevailing winds You will H need to install a flooding type Turm TETEN head pressure control such as Wale an electric solenoid or AEV and base the fan cycling on the ambient temperature with PROPER EA pressure override A pressure uses control connected to the high 364 side se
506. vice valve and let the system pump down Watch for the low switch opening then open the liquid line valve and watch for the high switch closing It must close as soon as the compound gauge rises to the cut in pressure AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 143 CAUTION Perform these checks for a brief time only to avoid damage to the unit LOW SIDE PRESSURE MOTOR CONTROL SETTINGS FOR TYPICAL REFRIGERATION APPLICATIONS Inches Vacuum Refrigeration applications Florist box Vegetable display Walk in cooler Beer cooler Show case Reach in cooler Frozen food open display case Frozen food closed display case Beer milk water cooler Soda fountain Ice machine Figure 93a Il HIGH PRESSURE CONTROL HIGH PRESSURE CUT OUT It is primarily a safety device which differs from the low pressure control Its sensing bulb is connected to a service valve on the discharge line by a flare nut When the head pressure in the system approaches a dangerous level it will automatically shut off the electrical power to prevent a compressor burnout through overheating In many commercial units depending on the type of refrigerant being used the cut out pressure is never set higher than 300 psi to prevent damage to the system As a rule of thumb the high pressure control is usually set to cut out the power at about 2096 above normal head pressure which is 165 psi for units using R 12 275 psi for units using R 22 200
507. water but the principle isthe same aster Linen Courtesy of Coari and Associates 203 204 TYPICAL COMBINATION WATER FOUNTAIN AND HOT WATER DISPENSER A combination water fountain and hot water dispenser typical of those available today This combination water fountain and hot water dispenser by OASIS has a 1 5 hp 5 Acompressor It is charged with 5 oz of R 12 and produces cold water at the rate of 8 gph gallons per hour ITEM NO DESCRIPTION 1 Bubbler valve Bubbler valve gasket Friction washer Gooseneck Drain screw Condenser shroud Top screw Gasket under top Waste gasket Hot valve gasket Hot valve body assembly Check valve Hot thermostat kit with clip Heat limiter kit with clip Hot tank Precooler or waste assembly Insulated cooling tank assembly Cooling tank insulation RH Cooling tank insulation LH Utility cover painted Utility cover stainless steel Cold control Condenser Overload Service Compressor includes items 28 and 29 Fan blade Fan motor Fan motor bracket Side panel painted Side panel stainless steel Front panel painted Front panel stainless steel 38 Rear panel painted Rear panel stainless stee 39 Shelf assembly 40 Paddle switch 41 Bubbler spud NOT SHOWN Terminal base Base cover Glass filler installation kit Foot pedal kit
508. ways pay close attention to the watt rating of the motor to be replaced The new fan must have at least the same wattage and revolution per minute A fan motor with lower revolution per minute turns slower causing a considerable loss in the efficiency of the evaporator or the condenser Consequently reducing the efficiency of the unit Fan motors do not usually come with blades Buying them separately will facilitate getting an exact match for the replacement An instruction sheet is included with the new motor Before removing the old fan note the direction of the motor rotation and the angle of the blade Incorrect assembly changes the direction of the airflow causing the unit to malfunction 84 TESTING EVAPORATOR FAN MOTORS The function of the evaporator fan is to force cold air from the freezer compartment into the refrigerator compartment and to circulate air over the cold evaporator coil It is located in the freezer compartment behind the evaporator cover and fan support plate If the unit fails to cool and you notice an accumulation of ice on the evaporator panel and you are suspicious of a fan motor that does not operate or TESTING AN EVAPORATOR operates at a lower speed in general FAN MOTOR everything said about checking a condenser fan motor holds true for an evaporator fan motor See fig 59 HOW TO TEST AN EVAPORATOR FAN MOTOR 1 Open the freezer door and listen for the fan motor If the fan is not heard o
509. will be heard as the ice melts and the pressures in the system begin to equalize A restricted drier feels cooler to the touch than normal The obstruction within the drier prevents the free flow of refrigerant causing evaporation A QUICK TEST FOR A RESTRICTION OR LEAK IN RESIDENTIAL UNITS When a residential unit runs warmer than normal or does not cool the problem can be due toa leak or a restriction in the system or several other reasons Check the following before conducting this test a condenser fan b evaporator fan c door gasket d linted condenser e cabinet light Does it stay on while door switch is depressed f cold control thermostat settings g high ambient and frequency of cabinet door openings by customer and h defrost system timer termination switch heater If items a through h are working correctly begin the test Connect power to unit Install a piercing valve on the suction line and connect it to the compound gauge hose While the unit operates check the pressure in the suction line with the valve on the gauge closed If the suction pressure reads above zero stop the test The problem is an inefficient compressor which must be replaced If the suction pressure reads below zero a vacuum continue the test to step 6 Look to see if the last pass of the capillary tube the drier or the condenser is sweating or cold If so the problem is a restriction in the system If the entire con
510. wing nut Water level control hardware valve body cotter pin cap spacer rubber plunger fiber washer nut sleeve and compression nut Float and stem assembly magnet bracket assembly and float Reed switch assembly Water level bracket Reed switch clamp Screw 6 32 x 1 4 long e E TE Courtesy of Wilshire Corporation Schaumburg Illinois 198 TROUBLESHOOTING COMMERCIAL ICE MACHINES Problem and Possible Cause No Ice in the Bin while Compressor Runs 1 Hot gas bypass solenoid stuck open 2 Leak in the sealed system Water supply faucet turned off Water float inoperative Water solenoid valve bad Evaporator thermostat out of calibration or inoperative Excessive use of ice Cutter grid circuit open Mineral buildup obstructing water circulating system No Ice in Bin and Compressor Does Not Run Power supply disconnected Bin thermostat contacts stuck open Master switch left in Clean position Defective relay Defective compressor motor Master switch off Loose connection or broken wire Ambient air below 55 F 1 2 3 4 5 6 7 8 Bin Full of Ice and Compressor Runs Nonstop 1 Bin thermostat contacts stuck in closed position 2 Binthermostat out of calibration Little Ice Production Ambient air below 55 F Hot gas solenoid valve stuck partially open Poor refrigeration Faulty bin thermostat Too little water circulated over evaporator surface
511. with the unit in operation see fig 34 There should be about 5 volt decrease with the unit running If the voltage drops 10 volts or more there could be a bad wiring to the wall outlet b an overload such as an overcharged or restricted system or c a bad motor winding If the compressor fails to start with sufficient line voltage reaching the motor check the overload protector and the starting relay if applicable If they check OK disconnect the wiring from the compressor motor and check it with a compressor test cord see fig 35 See figure 36 for testing a capacitor start capacitor run motor or a capacitor start induction run motor If the compressor fails to operate when tested it must be replaced 328 Compresanr Fas Hun Capaciter Capacitar Tharmaozxtat mot satisfies rbprmessor and fan im operation Compressor with Internal Overload Frobecter vapiti bnt Bun Cmpaciknr Capacitor TEmrmostzat smly fas im operating Figure 191b Figure 191c AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 329 maim Switch Crack Beater A PICTORIAL WIRING DIAGRAM OF A WINDOW WALL AIR CONDITIONER Figure 192a Figures 192a and bare different styles of wiring diagrams of the same window air conditioner Figure 192a illustrates a pictorial diagram and 192b is a schematic wiring diagram It is much easier to read a schematic diagram than a pictorial one
512. within the conditioned area with good air circulation and an average temperature See fig 168 The types of thermostats that only control heating or cooling come with only two or three terminals whereas the basic combination thermostats controlling both heating and cooling come with four five or six wire terminals AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 259 Don t install a wall thermostat close to lamps heat producing appliances or where it is exposed to direct sunlight It must be installed five inches above the floor Figure 168a Thermostat Location ROUTING THE THERMOSTAT CABLE j pole for thwersosatat wirp Btnut gord wit B in chain attached fugeboard mirip molding Fi n du siis R Figure 168 When replacing an old thermostat that is good location use the existing wiring when in good condition If location is new install thermostat cable first Wiring must comply with local and national electrical codes Probe for obstructions in wall before drilling one half inch hole at thermostat location Remove one fourth ju QT TTE r round and drill a small hole for sighting see fig 168a 174 tition moked sir for basement drill three fourth inch hole in floor next to guide hole On basementless houses drill TYPICAL THERMOSTAT INSTALLATION one half inch hole through ceiling and into partition i from above see fig 168a
513. xplanatory 238 As mentioned earlier there are basically two types of fans 1 The axial flow type 2 The radial flow type fan or squirrel cage see fig 140a 1 The axial flow type is known as a regular type fan as air is moved along the axis of the fan motor shaft Whether air moves into or away from the motor depends upon the rotation of the shaft and the pitch of the blades If the evaporator fan motor in a residential refrigerator requires changing and a duplicate motor is not available a universal fan motor of the same size can be purchased even if the direction of rotation is wrong The shaft and rotor which are joined in those motors can be removed from one side and reinstalled on the other side of the stator By doing this the rotation is reversed The fan blade also must be reversed on the shaft to keep the airflow in the same direction as it was originally In larger air conditioners and commercial fans the direction of rotation can be reversed simply by reversing the motor polarity This can be done by connecting the wires of the new motor in accordance with its instructions 2 Radial flow fans are mostly referred to as squirrel cages or blowers In this type of fan the 145 A THREE SPEED SHADED POLE FAN Current Flow MOTOR 4 the Qian A SELECTOR SWITCH ARES A 1 SELECTED SPH Hgure 146 AIR CONDITIONING AND REFRIGERATION REPAIR MADE
514. y act erratic Relay wired incorrectly Faulty start capacitor or compressor Faulty pressure control Leak in sealed system Linted condenser or faulty condenser fan Check and repair cutter grid connection Check and replace grid Check for an extension cord that is too long or undersized Replace Check power receptacle for proper voltage and inform owner of an overload problem in the house wiring Inspect and correct problem Check and replace if necessary Bypass thermostat If short cycling stops replace thermostat Check electrical diagram and correct Check and replace if necessary Check and replace if necessary Check and repair as needed Check and repair as necessary Condenser Fan Will Not Run in Ice Making Period Machines of 50lbs or Less Fan blade caught on shroud Faulty fan motor Faulty evaporator thermostat Open circuit in wiring to the fan motor Water Dripping into Ice Cube Storage Bin Water line leak at water valve Water dripping from ice slab remaining on warm grid Water return line moved out of position Water reservoir overflowing Adjust shroud or blade as necessary Replace fan motor Replace thermostat Disconnect wires to fan motor and check for voltage If you have a correct reading replace motor If there s no power check for broken wire or bad connection Check and tighten connections Check cutter grid cutter grid circuit and minerals buildup on evapo
515. ystem by a flare nut through Wii Rcs i z an access valve The two manually operated Betting adjusting screws top regulate the pressures i in the system One is the cut in the other is the differential adjustment When the pressure in the system reaches a predetermined point the mercury switch tilts causing the electrical circuit to Uu ERU Balint the compressor to shut off until the pressure rises Riisal y Tris to a predetermined point during the off cycle Courtesy of Honeywell AIR CONDITIONING AND REFRIGERATION REPAIR MADE EASY 261 It has been mentioned that the mercury type wall thermostat is very sensitive to proper leveling and should be accurately installed to operate correctly Since homeowners are primarily concerned about the high cost of heating and cooling the solid state programmable thermostat is becoming more popular The heating and cooling cycles can be separately programmed to economically regulate temperatures for daytime and evening operation from day to day during a whole week summer or winter They come with detailed instruction manuals They are not sensitive to level adjustment INSTALLING A NEW THERMOSTAT When installing a new thermostat determine whether it is to be used for heating or cooling or both and find the most suitable location as suggested on page 259 Always follow the instructions that are included with each new unit INSTALLING A REPLACEMENT THERMOSTAT

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