DOLE REFRIGERATING COMPANY SEQUENTIAL DEFROST
Contents
1. Figure 1 System Variations SEQUENTIAL DEFROST SYSTEM VARIATIONS THE COMPONENTS IN THE COLD WEL CONTROL PANEL WILL REVEAL WHICH VERSION OF SEQUENTIAL DEFROST IS INSTALLED IM A SPECIFIC TRUCK SEQUENTIAL DEFROST WITH HEAT DOLE WIRING DIAGRAM 77270825 3 PLATES us m CONTROL PANEL SEQUENTIAL DEFROST WITH MANUAL INITIATE DOLE WIRING DIAGRAM 7727D377 3 PLATES AND 7525 4 PLATES SEQUENTIAL DEFROST WITH MANUAL INITIATE AND HEAT DOLE WIRING DIAGRAM 77270328 3 PLATES u EO d system Description A Dole COLD WEL with Sequential Defrost contains three or four plates filled with a zero degree F eutectic solution Each plate has an internal refrigeration coil 13 and an internal defrost coil 21 Upon the application of external power a plate is selected for defrost The remaining plates are placed in the refrigerate mode The description that follows and the illustration pertain to the three plate Sequential Defrost configuration Defrost is accomplished by energizing the Liquid Solenoid Valve 7 8 or 9 and the Hot Gas Solenoid Valve 15 16 or 17 on the plate selected for defrost The compressor discharge is routed through the open Hot Gas Solenoid Valve through the plate s defrost coil out the Hot Gas Return Check Valve 18 19 or 20 and to the Condenser 4 The condensed liquid is stored in the Receiver 5 At the same time liquid refrigerant is routed through the King Valve 6 and through2. The defrost cycle will be terminated when a temperature sensor indicates that the hot gas exiting the plate undergoing defrost has reached 70 degrees F At that time the defrosted plate will be placed in the refrigerate mode and refrigerant will flow through its coil Should external power be interrupted for any reason i e power failure or intentional disconnect as a result of moving the truck the defrost cycle for the selected plate will be terminated Subsequently when external power is restored the Cycle Timer will select the next plate due for defrost and will position the refrigerant and hot gas valves in such a manner that this plate will be in the defrost mode and the remaining plates will undergo refrigeration sequential Defrost with Winter Heat In this configuration a manually operated selector switch is included which can place the unit in the Refrigerate or in the Heat mode In the Refrigerate mode the system operates in the same manner as the Sequential Defrost just described When placed in the Heat mode a heater in the Cold Wel energized and air flows over the heater when the truck thermostat calls for heat While in the Heat mode the Condensing Unit is electrically locked out Heat is available only at dockside since the heaters are 240VAC elements Sequential Defrost with Manual Initiate When external power is connected to the truck depressing the momentary contact Manual Initiate Switch on the external Control Box
3. This power is supplied by the truck battery or by external power when the truck is at dockside When external power AC is connected to the truck Relay R2 will be energized and DC power will be available to the Blower motor MI from the Rectifier FWB1 and not the Battery amp This is true whether or not the Dash Switch D S is closed The Cycle Timer Motor M2 in the cycle timer loop can have 6 or 8 cams The 6 cam configuration for 3 plate units is shown here An 8 cam Cycle Timer is required for a 4 plate configuration The instant that external power is connected to the truck the Time Delay Relay TDR is energized and voltage is available to the Cycle Timer Motor M2 through the normally closed contact of the TDR After approximately one second this contact opens The timer cams will rotate for a third of a revolution 120 degrees at which point one of the cams 2 4 or 6 will open breaking the circuit to the timer Then one of the timer s cams 1 3 or 5 will be closed the other two will be open Since the Liquid Solenoid Valves LSVI 2 and 3 are normally open valves and the Hot Gas Solenoid Valves HSV1 2 and 3 are normally closed valves the cam that is closed will dictate which plate is to be defrosted and which plates refrigerated Defrost continues until TC2 senses that the return hot gas exiting from the plate being defrosted has reached 70 degrees F At that time TC2 will close and R3 will be energized
4. he normally closed contact of R3 opens all plates are placed in the refrigerate mode R3 remains energized until external power is removed The system remains in the refrigerate mode as long as external power remains connected Should power be interrupted for any reason its reapplication will cause the next plate in line to be placed in defrost and the complete cycle will begin again Figure 3 Sequential Defrost SCHEMATIC 230 1 60VAC 12 0 L1 L2 Ae 13 CAM 1 CLOSED 0 120 14 Bun CAM 3 CLOSED 120 240 45 ja CAM 5 CLOSED 240 380 g o CAM 2 CAM 4 CAM amp S OPEN 60 62 OPEN 180 182 OPEN 300 302 08 ron uc 12 TC2 21 L1 R3 21 Je 14 Sequential Defrost with Heat Operation Refer to Figure 4 The operation of this version of Sequential Defrost is identical to that of the system just discussed when cooling is called for in the truck However there is an additional circuit the winter heat circuit that affects the operation of the system The heat circuit includes a Refrigerate Heat Switch SW3 an On Off Switch SW2 a Heater HTR a High Limit Switch H L a Truck Thermostat TC1 and a Heat Initiate Relay R3A With the Refrigerate Heat Switch in the Refrigerate position the system operates in the same manner as the one just discussed The heater is actuated when the Refrigerate Heat Switch is p
5. repairing the defective part whichever it seems advisable 32
6. the open Liquid oolenoid Valves 7 8 or 9 on plates being refrigerated After passing through the two appropriate Thermostatic Expansion Valves 10 11 or 12 the cold liquid refrigerant flows through the internal refrigeration coils 13 is vaporized and routed through the Suction Accumulator 14 to the Compressor 1 A special feature of this system is the Spring loaded Check Valve 3 This valve requires a 30 psi differential pressure across it to open During the defrost mode hot gas follows the path of least resistance through the defrost coil 21 of the selected plate During this time the coil acts as the system condenser Defrost is terminated by the Defrost Terminate Thermostat 22 which senses the temperature of the hot return gas as it exits the defrosted plate When the temperature of this gas reaches 70 degrees F defrost is terminated and all three plates are placed in the refrigerate mode Figure 2 Refrigeration System UNIT CONDENSING Refrigeration Equipment Items Refer to Figure 2 Hef No Nomenclature c 3 3 Compressor Discharge Service Valve opring loaded Check Valve Condenser Receiver Liquid Line King Valve Liquid Solenoid Valve No NO Liquid Solenoid Valve No 2 NO Liquid Solenoid Valve No 3 NO Thermostatic Expansion Valve No 1 Thermostatic Expansion Valve No 2 Thermostatic Expansion Valve No 3 Inter
7. to the applicable electrical schematic for the discussion that follows Figure 3 4 5 or 6 Troubleshooting Blower motor fails to run over the road In transit assuming truck doors are closed and the Truck Thermostat TC1 calls for cooling the Blower Motor MI should run off of truck battery power B to B Failure of the motor to run under these conditions can produce the following symptoms 1 Warm product and truck body temperature 2 No noticeable movement of air in the truck If such is the case the following should be checked 1 The toggle switch D S mounted on the truck dash should be in the on position Indicator light P4 should be lit 2 If M1 runs when contact arm of R1 is depressed the probable cause of trouble is the R1 coil circuit If the motor fails to run when the R1 contact arm is depressed check for the following 1 Open Circuit Breaker CB 2 No voltage between B at M1 and Ground If M1 runs at reduced speed check for the following 1 Brushes making poor contact 2 Worn brushes and or low brush spring tension 3 Check voltage across motor M1 If low find cause loose connection etc Troubleshooting Blower motor will not operate on AC power If MI operates on DC power but not on AC two circuits must be checked 230 VAC and 12 volt rectified circuit 1 All Door Switches D R should be closed 2 TC1 should be set low enough to call for cooling 3 R1 should be energized 4 230
8. will cause the Cycle Timer to select a plate for defrost and place the remaining plates in the refrigerate mode This operational mode will be maintained until the defrost cycle is completed at which time the defrosted plate will be refrigerated as was the case in systems without the Manual Initiate feature should the power be interrupted for any reason a resumption of power will permit the system to continue operating in the same mode as before power was interrupted This is accomplished by a latching relay in the external Control Box In other words if power was interrupted with a specific plate in the defrost mode subsequent restoration of power will permit the continuation of defrost of that plate For any plates in the refrigerate mode at power interruption restoration of power will allow the refrigeration of those plates to continue Sequential Defrost with Manual Initiate amp Heat A system in this configuration operates in the same manner as the one just described except as was the case with Sequential Defrost placing the Refrigerate Heat Switch in the Heat position prevents the Condensing Unit from operating and places the unit s blower under the control of the truck s thermostat Whereas this thermostat will call for cooling with rising temperature when the system is in the Refrigerate mode it will call for heating with falling temperature when in the Heat mode Heat is available only at dockside since the heaters require 240 VAC
9. 15 VAC minimum is not available across the two AC terminals of FWB1 check voltage across the Transformer Primary If 230 VAC is not available check main power source to truck 2 If 230 VAC is available across the coil of R2 and the coil is not energized replace R2 3 If 230 VAC is not available across the coil of R2 check for 230 VAC to LI and L2 terminals on FWB2 4 If 230 VAC is not available locate the source of power failure Troubleshooting Reduced air flow from blower Symptoms of reduced air flow can be warm body and product temperature and or no noticeable air movement in truck It can result from the following 1 Dirty commutator or worn brushes cause motor to run at reduced speed 2 Defective Rectifier FWB1 3 Excessive ice buildup on plates due to improper defrosting See Troubleshooting Defrost fails to terminate If reduced air flow is detected the following sho uld be checked 1 Toggle Switch D S on truck dash should be on 2 Depress contact arm of R1 Relay If M1 begins to run fault is in the RI Relay circuit 3 If M1 does not run check CB for open circuit 4 Check voltage across M1 should be 12VAC minimum If lower check for loose connections 3 If M1 continues to operate at reduced speed check for brush wear and reduced spring tension 6 Check fan for proper rotation Blades should be moving downward as viewed from in front of the unit See Troubleshooting Blower motor reverses dire
10. DOLE REFRIGERATING COMPANY 1420 Higgs Road e Lewisburg Tennessee 37091 Phone 931 359 6211 1 800 251 8990 www doleref com SEQUENTIAL DEFROST SERVICE MANUAL June 2002 Fop SEQUENTIAL DEFROST Table of Contents Introduction COLD WEL Auto Sequential Holdover Blower System COLD WEL Sequential Defrost System Configurations Refrigeration System Description Refrigeration System Equipment Items sequential Defrost Operation Sequential Defrost With Heat Operation sequential Defrost With Manual Initiate Operation Sequential Defrost With Manual Initiate amp Heat Operation Operation of Defrost Cycle Termination Control Settings Troubleshooting Blower Motor Fails to Run Over the Road Blower Motor Will Not Operate on AC Power Defrost Cycle Fails To Terminate Battery Drained While operating on AC Heduced Air Flow From Blower Blower Motor Reverses Direction Winter Heat Failure Cycle Timer Will Not Advance oystem Will Not Go Into Defrost Ice Buildup on Plates Ice Buildup on Compressor Charging the System Replacement Parts Warranty 2202 List of Illustrations Figure 1 Cold Wel System Variations Figure 2 Refrigeration System Figure 3 Sequential Defrost Electrical Schematic Figure 4 Sequential Defrost with Heat Electrical Schematic Figure 5 Sequential Defrost with Manual Initiate Electrical Schematic Figure 6 Sequential Defrost w Manual Initiate and Heat Electrical Sc
11. VAC should be available at the LI and L2 terminals of FWB2 Terminal otrip in the Control Panel 5 Press H1 contact arm down with an insulated object 6 If M1 does not run check CB Replace if open 7 I M1 runs check R1 for 12VDC If available across the coil replace H1 8 Check position of R2 contact arm It should be in a downward position when operating off of AC power 9 Check Primary and Secondary voltage across XMFR1 wires LI and L2 for Primary and 22 and 23 for Secondary Primary voltage should be nominally 230 volts and Secondary a minimum of 15VAC 10 Check FWB1 output If less than 12 volts replace 23 Troubleshooting Defrost cycle fails to terminate The Defrost Termination Relay R3 is equipped with a neon light that illuminates when energized To check the status of R3 proceed as follows 1 Remove panel to gain access to the Control Panel 2 Observe R3 relay If light is lit relay is energized and all plates should be in the refrigerate mode 3 If R3 is not energized light off either TC2 has not yet sensed 70 degrees F in the hot gas return line from the plate under defrost or the R3 relay is defective 4 Check for voltage to R3 If voltage is present check for continuity across the R31s normally closed contact wire LI to 13 If there is continuity R3 is defective and should be replaced NOTE When defrost terminates a change can be noticed in the sound of the compressor Shortly after defrost termi
12. air exiting the Cold Wel If low temperature is indicated check for the following 1 External 230VAC power available to truck The heaters operate off of 230VAC power only 2 Check for heat in the vicinity of the Heaters Do not touch the Heaters If no heat is detected check for 230VAC across the Heaters If voltage is present disconnect external power from truck and check for continuity across the Heaters If Heater s is open replace defective unit s 3 Door Switches D R should be in closed position and operable Blower will not operate otherwise 4 The Refrigerate Heat Switch SW 3 should be in the Heat position 5 Check the setting of the Truck Thermostat TC1 It has a set point for cooling and one for heating Check to determine if it is closed and calling for heating Adjust or replace as appropriate 6 Check the setting of High Limit Switch H L It is set to open at 80 degrees F and close at 65 degrees F Adjust or replace as appropriate 7 the High Limit Switch H L is closed check the status of the Heater Relay R3A It should be energized and its normally open contact should be closed If this contact is closed check the status of the normally open contacts of the DC Relay RI These contacts RIA amp R1B should be closed when RI is energized If RI is de energized check for the presence of 12VDC across the output of the Rectifier FWB1 Check for presence of 12 VAC across the AC terminals of the Recti
13. ch a plate into the defrost mode To charge the system proceed with the following 1 Disconnect one wire from the high low suction pressure control and tape the end 2 Apply power to the unit NOTE With high low suction pressure control out of the circuit the compressor is inoperative When power is supplied to the unit the liquid solenoid and hot gas solenoid valves LSV1 2 or 3 and HGSV1 2 or 3 are energized and liquid is free to flow through the plate cooling coils 13 3 Connect a drum of refrigerant to the system Allow refrigerant vapor to enter system equalizing on both the high and low sides 4 Disconnect the refrigerant drum Connect a drum of nitrogen Allow nitrogen to enter system building pressure to approximately 265 psig 5 Leak test the system 6 Purge all gases from the system 7 Attach vacuum pump Pull vacuum on system 8 Charge system with refrigerant 30 REPLACEMENT PARTS Seguential Defrost with Manual Initiate amp Heat Seguential Defrost with Manual Initiate Sequential Defrost with Heat Sequential Defrost Sym Part No Description 10 423 Transformer 230 16VAC X X X X XFMR2 10 167 Transformer 230 120VAC X X Ri 10 522 Relay 12VDC SPST X X RI 10 527 Relay 12VDC DPST X X R2 10 521 Relay 230VAC X X X X R3 10 520 Relay 230VAC X X X X B3 10 532 Socket for 10 520 Relay X X X X R3A 10 528 Relay 12VDC X X R4 10 523 Relay 230VAC x X R5 10 520 Relay 230VAC X X B5 10 532 Soc
14. ction Troubleshooting Blower Motor reverses direction If the Blower Motor MI runs in one direction when on Battery Power DC and in the opposite direction when on External Power AC check for the following 1 Determine correct fan rotation fan rotation on DC or on AC power The air should be expelled from the two vertical rectangular outlets in the front of the Cold Wel when rotation is correct 2 f rotation on DC power is correct reverse wire to the Positive and Negative C terminals of the Rectifier FWB in the Control Box Wires 31 and 3 in units without winter heat Wires 31 and 10 in units with Winter Heat 3 If rotation on AC power is correct and if wires 31 and 3 or 10 are routed to the Rectifier FWB1 per the Schematic reverse wires 1 and 8 at the most 26 convenient location i e the Battery Terminals B and at the Control Box Terminal Strip FWB2 or at the External Junction Box FWB5 4 If rotation on AC power is correct and if wires 31 and 3 or 10 are routed incorrectly to the Rectifier FWB1 reverse wires 31 and 3 or 10 to conform to the Schematic and reverse the motor leads wires 11 and 12 to the Circuit Breaker CB and to the DC Relay RI in the Control Box Troubleshooting Winter heat failure Evidence of heater failure can be one or more of the following 1 Lower than desired temperatures in truck 2 Product beginning to freeze 3 Blower inoperative 4 Very cold
15. d by hot gas flowing through its defrost coil To replace such a valve 1 Remove external power 2 Remove and replace valve See Charging the System Troubleshooting Defrost fails to terminate If a unit does not sequence to the next plate af ter disconnecting and reconnecting power or in systems with Manual hitiate af ter depressing the Manual Initiate Switch SW 1 check Cycle Timer M2 for rotation If there is none proceed as follows 1 Disconnect power 2 check for continuity through M2 leads If no continuity replace Cycle Timer M2 DO NOT TRY TO REPLACE MOTOR ONLY 3 Disconnect wires LI and L2 from the TDR check for continuity If none replace the TDR lf M2 runs continuously disconnect wire LI from TDR If M2 stops TDR is defective and should be replaced If M2 continues to run programming of the Cycle Timer should be checked If resetting the cams properly does not resolve problem replace the Timer Troubleshooting Battery drained while operating on AC When external power is applied to the system R2 will be energized This will open the circuit from the Battery and close the circuit to the Rectifier FWB1 If R2 is defective 25 M1 will continue to operate off the battery power even though external power is available If allowed to continue the truck battery could be completely drained To check the R2 Relay coil circuit proceed as follows 1 Check Secondary output of Transformer XMFR1 If
16. eezing and the waste of holdover cooling when truck doors are open and or the truck thermostat is not calling for cooling Since the Cold Wel frame is insulated product can be stored up next to the unit without fear of freezing 3 Dual blowers on a double shafted motor provide a high velocity blast of air along the ceiling to the rear of the body for full product protection The blower motor is powered from the truck battery while on the delivery route and by external power when the condensing unit is plugged into external power at dockside for the purpose of refreezing eutectic in the plates 4 The air inlets are located near the top of the unit to receive the warmest air in the body This is especially important after a door opening has resulted in an inrush of air from outside with its accompanying higher temperature 5 The closed bottom of the unit permits product to be stacked against the exterior of the Cold Wel a feature that permits full use of available floor space This feature also prevents water which flows off of the plates during defrosting from flooding the truck body floor The rapid reduction of body temperature after door openings inherent in the Cold Wel design results in reduced total blower motor heat load and a reduction in the total load on the truck battery 6 During the plug in period hot gas is directed to the hot gas coil in the preselected eutectic plate This hot gas circulates through the coil and melt
17. f heat that must be transferred to the greater amount of eutectic 21 Control Settings Refer to Figure 2 The Hot Gas Defrost coil 21 located within a plate functions as the condenser during that plate s defrost cycle Therefore it is critical that head pressure be properly controlled during the defrost cycle A high head pressure equates with hotter gas for defrost while a low head pressure and its resulting lower temperature gas would tend to increase the time required to defrost a plate A spring loaded Check valve 3 prevents the Compressor discharge from going directly to the Condenser 4 until it has passed through the Hot Gas coil 21 This valve is set to open when the pressure differential across it rises above 20 psig A Defrost Terminate Thermostat 22 monitors the exit temperature of the hot gas to assure that defrost is complete The Thermostat is set to terminate defrost when the exiting hot gas temperature reaches 70 degrees F A Condenser Fan Control Switch controls variations in head pressure and is set to cut in at 265 psig and cut out at 220 psig A Suction Pressure Control Switch is set to cut out at 6 psig and cut in at 16 psig A Crankcase Pressure Regulator may be used to limit the load on the compressor If used this regulator should be set to close at the maximum running load amperes of the condensing unit during the initial pulldown of the refrigeration system 22 Troubleshooting Refer
18. fier 8 If 12VAC is not present across the Rectifier FWB1 check the Secondary voltage of XFMR1 At least 12 to 15VAC should be available from the Secondary 9 If Blower MI is inoperative check Troubleshooting Blower motor will not operate on AC power Troubleshooting Cycle Timer will not advance In systems with Manual Initiate depressing the momentary contact Manual Initiate Switch SW 1 will cause the Cycle Timer M2 to rotate approximately 120 degrees for 2 a 3 plate Cold Wel or for 90 degrees for a 4 plate Cold Wel As a result a plate is selected for defrost and the remainder of the plates are selected for refrigeration If the Cycle Timer does not rotate when SW 1 is depressed the following should be checked 1 Depress SW 1 and check for 230VAC to M2 If voltage is present check Cycle Timer cams for resistance to rotation by manually rotating them Check for presence of foreign material which could retard rotation 2 f the Cycle Timer rotates only when SW 1 is depressed check cams 2 4 and 6 for proper setting Reset as appropriate 3 Disconnect external power Check for continuity across Cycle Timer M2 If open circuit replace M2 Do not attempt to replace only a portion of Timer Troubleshooting System will not go into defrost In systems with Manual Initiate the ONLY way to cause the Cycle Timer to rotate and put a new plate in defrost is to depress the Manual Initiate Switch SW 1 Normall
19. g the effectiveness of the defrost and refrigerate functions It is important to remember that the Manual Initiate Switch must be activated once when the truck is first connected to external power for its pulldown to assure that the next plate due for defrost will be selected If this is not done the plate last defrosted will be defrosted again Figure 5 Sequential Defrost with Manual Initiate ws D iri Hi ER AE ALE MATT EE e30 17 60 CAM amp 3 CLOSED 120 4 LAM w5 CLOSED 24g 35 CAM 2 DFEN CAM 4 OPEN CAM 6 OPEN 60 1860 188 300 HME a EAR BE um xs E 18 sequential Defrost with Manual Initiate and Heat Operation Refer to Figure 6 The method of controlling defrost refrigeration and blower operations is the same as the system with Manual Initiate The method of controlling heat is the same as for the sequential Defrost with Heat option DOLE Figure 6 Sequential Defrost with Manual Iniate and Heat SCHEMATIC 2341 6 le VOC ag Re MEET EAG LE un KAREL wg 20 4 CAM 85 CLOSED 240 360 CAM m2 OPEN CAM m4 OPEN 86 OPEN 60 GE 189 a 302 20 Operation of Defrost Cycle Termination In all Sequential Defrost configurations the defrost cycle is terminated automatically oince hot gas defrost is accomplished by transferring heat from the gas ci
20. ge and Suction Service Valves 2 and 23 Remove refrigerant from system Unsolder valve from system and replace NOTE Never work in the presence of liquid refrigerant without wearing safety goggles and protective clothing 24 Troubleshooting Defrost Cycle fails to terminate The system includes a Defrost Terminate Thermostat TC2 which terminates defrost when hot gas returning from a defrosted plate reaches a temperature of 70 degrees F Failure to terminate defrost can be caused by a thermostat set incorrectly or one with a broken sensing bulb A defective R3 Relay can also result in failure to terminate defrost Should a defective Defrost Terminate Thermostat be observed it should be replaced as follows 1 Disconnect power source 2 Remove upper blower section cover 3 Remove insulating tape from sensing bulb 4 Remove clamps holding sensing bulb 3 Hemove cover from the thermostat and disconnect two wires Remove thermostat holddown screws Remove thermostat 6 Repeat above in reverse to install new thermostat NOTE Insulating tape must be used to install the sensing bulb on the thermostat Lack of insulation can prevent the system from terminating defrost Troubleshooting Defrost cycle fails to terminate Should dirt or other foreign material prevent a Hot Gas Solenoid Valve from closing when defrost is completed even though the defrost cycle is over electrically the plate s eutectic is still being warme
21. hematic 11 14 16 18 20 Introduction The purpose of this manual is to describe the Dole Sequential Defrost Cold Wel and to present information relative to its maintenance An attempt has been made to offer as much practical assistance as might be required to troubleshoot and resolve problems that may arise A Cold Wel ready for installation in a truck ACCESS TO ELECTRICAL CONTROL PANEL COLD AIR SUPPLY WAHM AIR RETURN 4 A ie ACCESS TO as hek 4 mid i REFRIGERATION bei oL rs EXTERNAL n ay JUNCTION BOX Cold Wel Auto Sequential Holdover Blower System Features of Cold Wel Sequential Defrost Hoover Blower Systems 1 The special dual circuit zero degree F holdover plates provide twice the plate surface to body air temperature difference as plus 18 degrees F plates in other holdover blower systems This feature results in Cold Wels having the capacity to cool an enclosure at twice the rate of other systems Cold Wel units can contain three or four plates each plate having two independent coils One coil is used for cooling and freezing the eutectic solution while the other is used for defrosting the eutectic solution by means of circulating hot gas 2 The top air intake and discharge openings result in a cold trap within the Cold Wel This trap prevents cold heavy air from flowing out of the unit when the blower fan is off This feature diminates product fr
22. ice will normally disappear after a few minutes of compressor operation However if ice continues to accumulate on the Suction Line Accumulator and the Suction line to the Compressor it is an indication that one or more of the Thermostatic Expansion Valves is malfunctioning To determine whether or not a Thermostatic Expansion Valve is malfunctioning check for the following Check the temperature of each suction line where it exits from a plate and before it enters the common suction manifold The line with the lower temperature is most probably the valve that is hanging open NOTE Before replacing a Thermostatic Expansion Valve that is suspected of being faulty check to assure that the valve s thermal bulb is tightly clamped to the suction line and properly insulated DO NOT ALLOW THE SYSTEM TO CONTINUE OPERATING WITH AN ACCUMULATION OF ICE ON THE COMPRESSOR 29 Charging the System IMPORTANT Start with a minimum of 35 pounds of refrigerant Continue charging during defrost until the system exhibits a full sight glass If it is necessary to add refrigerant after repairing a leak or to clear a sight glass when the system is operating in the defrost mode cycle each plate through defrost by disconnecting and reconnecting the external power This should insure that refrigerant is present in all of the defrost coils in the plates In systems with Manual Initiate the Manual Initiate Switch SW 1 must be depressed momentarily to swit
23. ket for 10 520 Relay X X LR 10 163 Relay Latching 115VAC X X BLR 10 164 Socket for 10 163 Relay X X TDR 10 517 Relay Time Delay 230VAC X X TDRI 10 518 Relay Time Delay 230VAC X X CB 11 709 Circuit Breaker 12VDC X X X X FWBI 10 816 Rectifier 16GVAC I2VDC X X X X H S 10 814 Heat Sink Compound for 10 816 X X X X FWB2 11 115 Terminal Strip 18 Loc X X X X M S2 11 116 Marker Strip for 11 115 X X X X FWB3 11 109 Terminal Strip 4 Loc X X X M S3 11 152 Marker Strip for 11 109 X X X FWB4 11 107 Terminal Strip 8 Loc X X M S4 11 154 Marker Strip for 11 107 X X FWBS 11 101 Terminal Strip 10 Loc X X X M SS 11 151 Marker Strip for 11 101 X X X X FWB6 11 108 Terminal Strip 3 Loc X X M S6 11 155 Marker Strip for 11 108 X X TCl 06 064 Thermostat Truck X X X X TC2 06 073 Thermostat Defrost Terminate X X X X SWI 10 224 Switch Momentary Contact X X SW3 10 213 Switch Ref Off Heat X X D P 27 606 Plate for 10 213 X X MI 09 317 Blower Motor X X X X M2 10 511 Cycle Timer X X X X PI 11 419 Light 230VAC Green X X P2 11 416 Light 230VAC Red X X P4 11 412 Light 12VDC X X X X D R 10 224 Switch Door X X X X D S 10 206 Switch Dash X X X X D P 27 605 Plate for 10 206 X X X X LSV 28 123 Liquid Solenoid Valve NO X X X X HGSV 28 120 Hot Gas Solenoid Valve NC X X X X HTR 24 113 Heater 230VAC X X H L 06 060 Switch High Limit X X CV 28 211 Check Valve Hot Gas Return X X X X 31 Warranty Sequential Defrost Blower Unit The Company
24. laced in the Heat position since the Heater operates only off of AC power this circuit is only effective when the truck is connected to external power at dockside As long as RSA is energized the Compressor Contactor Cl sees an open circuit rendering the Compressor incapable of operating Whereas the Truck Thermostat TC1 calls for cooling on temperature rise when in the refrigerate mode it will call for heat with a decrease in temperature when in the heat mode Figure 4 Sequential Defrost with Heat SCHEMATIC 230 1 60VAC pe 12VDC Li 2 25 Y 2b Ecol 5 OFF 29 ON 28 HIR CAM 1 CLOSED 0 120 14 CAM 3 CLOSED 120 240 15 CAM 5 CLOSED 240 360 16 13 CAM 2 CAM 4 CAM 6 OPEN 60 62 OPEN 180 182 OPEN 300 302 sv3 18 19 TE2 21 j Le R3 2 sequential Defrost with Manual Initiate Operation Refer to Figure 5 The operation of the ready loop in controlling the blower is identical in all versions of sequential Defrost The operation of the Cycle Timer is also identical in all versions However the initiation of defrost and the termination of defrost are somewhat different A Manual Initiate Control Box is an added feature of this configuration The box contains a Latching Relay LR an Enabling Relay R5 a Control Transformer XFMR2 and a Defrost Initiate Switch SW1 As was the case in systems without Manual Initiate the Defrost Termi
25. nal Plate Refrigerant Coil Suction Accumulator Hot Gas Solenoid Valve No 1 NC Hot Gas Solenoid Valve No 2 NC Hot Gas Solenoid Valve No 3 NC Hot Gas Return Check Valve No 1 Hot Gas Return Check Valve No 2 Hot Gas Return Check Valve No 3 Internal Plate Defrost Coil Defrost Terminate Thermostat Suction Service Valve Part No 28 123 28 123 28 123 28 120 28 120 28 120 28 211 28 211 28 211 Not spared 06 073 Cold Wel Condensing Unit System shown in Figure 2 is a three plate unit In a four plate unit an additional liquid solenoid valve hot gas solenoid valve thermostatic expansion valve and hot gas return check valve would be included Part supplied by others Sporlan TEVs 28 429 R502 and 28 431 R22 Alco TEVs 28 423 R502 and 28 427 R22 Sequential Defrost Operatiion Refer to Figure 3 There are two basic circuits in a Sequential Defrost System 1 The ready loop It must be closed to permit blower operation The ready loop includes a Dash Switch D S on the truck dash a Truck Thermostat TCI two Door Switches D R and a DC Relay H1 2 he cycle timer loop It determines which plate is to be defrosted and which plates are to be refrigerated The loop includes a Cycle Timer M2 2 cams per plate a Time Delay Relay TDR and a Defrost Terminate Relay R3 When all items in the ready loop are in the closed position the blower operates on direct current DC power
26. nate Thermostat TC2 terminates defrost by sensing the temperature of the hot gas exiting the plate being defrosted The important difference between this system and versions without the Manual Initiate feature is as follows 1 In all Sequential Defrost configurations the removal of external power stops defrost and refrigerate functions 2 In configurations without Manual Initiate the application of power will cause the Cycle Timer to rotate 120 degrees placing a new plate in the defrost mode and placing the other plates in the refrigerate mode 3 In systems with the Manual Initiate feature application of external power will cause the system to continue operating in the same mode in which it had been operating when external power was last interrupted In other words if a plate was in the defrost mode and the other plates were being refrigerated at power interruption the reapplication of power would simply permit them to continue in those modes 4 In systems with the Manual Initiate feature it is necessary to depress the momentary contact Defrost Initiate Switch SW1 to cause the Cycle Timer to place a new plate in the defrost mode In summary the Manual Initiate feature prevents the system from arbitrarily removing a plate from the defrost mode before it had been completely defrosted as a result of a power failure or disconnecting and reconnecting external power It permits the moving of a truck during a plug in period without jeopardizin
27. nates the discharge line from the Spring Loaded Check Valve will become very hot to the touch 5 Check for continuity across TC2 wire LI and 21 If TC2 is open check temperature of hot gas return line from the defrosted plate in the vicinity of the TC21s sensing bulb If temperature is 70 degrees F or higher check setting of TC2 If TC2 cannot be adjusted to close at 70 degrees F replace it 6 Check operation of the Spring loaded Check Valve If this valve fails in the open position discharge gas is free to flow in two directions during defrost straight to the Condenser and through the defrost coil of the plate undergoing defrost If this situation exists the greatly diminished supply of hot gas to the plate will result in increased defrost time and possibly the inability to defrost at all If this valve fails in the open position the discharge line on either side of it should be equally hot to the touch 7 To replace the Spring loaded Check Valve proceed as follows Refer to Figure 2 Close the King Valve 6 Operate the system in the defrost mode on each plate Unplugging and reconnecting the external power will assure cycling the system through each plate on systems without Manual Initiate Simply depressing the momentary contact Manual Initiate Switch will cycle another plate to the defrost mode This cycling should remove as much refrigerant as possible from each plate Disconnect power from unit Close Compressor Dischar
28. rculating through a plate to the eutectic solution in the plate the amount of heat transferred will be reduced as the eutectic solution is melted As a result the hot gas exiting the plate will be warmer due to the fact that it transfers less heat to the eutectic as the eutectic temperature rises above its freezing point A thermostat installed in the hot gas return line and set to close at 70 degrees F acts to terminate the defrost cycle At this time the defrosted plate is placed in the refrigerate mode Note Each time the external AC power source is interrupted regardless of the reason the defrost and refrigerate cycles are terminated Upon the resumption of power both cycles will begin again However in units which do not have a Manual Defrost Initiate system a new plate will be selected for defrost In units with Manual Defrost Initiate if a plate was in the defrost mode when power was interrupted it will continue in that mode when power is reapplied until defrost is complete If the plate was in the refrigerate mode at the time of power interruption it will remain in that mode when power is reapplied until the cycle is complete Defrost time should not exceed four hours On warm days when most of the eutectic solution in a plate has been melted the defrost cycle will be shorter due to the small amount of eutectic to be melted On cold days when little solution has been melted defrost will take more time due to the greater amount o
29. s the eutectic in the plate The warmed solution melts the plate s surface frost The defrost cycle may be initiated automatically or manually depending upon the configuration of the Sequential Defrost system employed The defrost cycle is terminated when a temperature sensor in the hot gas return line indicates the plate s eutectic solution has been sufficiently heated to eliminate surface frost approx 70 degrees 7 A winter heat option is available in all Cold Wels This option can prevent product freezing when the unit is plugged into external power at dockside in Northern climes where heating may be required due to extremely low outside temperatures Cold Wel Sequential Defrost System Configurations Cold Wel sequential defrost is offered in four different configurations Sequential Defrost Sequential Defrost with Heat Sequential Defrost with Manual Initiate Sequential Defrost with Manual Initiate amp Heat Figure 1 illustrates the differences between the different configurations Sequential Defrost In this configuration plugging in external 230VAC power will automatically initiate defrost of a selected plate At the instant the external power is applied to the unit the Cycle Timer in the unit s Control Panel selects a plate for defrost Refrigerant and hot gas solenoid valves are opened and or closed to permit hot gas to circulate through the selected plate and to allow refrigerant to flow through the other plates
30. to assure sufficient refrigerant is in the system 2 Check the Condenser fan control cut in pressure setting It should be set at 265 psig A low cut in point will result in low discharge pressure which reduces the gas temperature available for defrosting 28 3 Check the setting of the Defrost Terminate Thermostat TC2 It should be set to close at 70 degrees F A lower setting will result in premature Defrost Terminate and result in a gradual buildup of ice on plates NOTE The buildup of ice on plates over a period of time will restrict the passage of air across the plates This reduced air flow coupled with the insulating effect of the ice severely limits the capacity of the plates to cool the truck and can result in higher than normal truck temperatures Other causes of ice buildup on plates can be plugged kazoo tubes This condition can prevent the defrost water from leaving the unit through the floor drains As a result the ice buildup on the floor can block air flow even though the plates have been properly defrosted A thin rod should be inserted into the kazoo tubes to assure that the drain is open A Blower Motor failure can also result in ice buildup See Troubleshooting of the various Blower Motor failures Troubleshooting Ice buildup on compressor When a compressor starts it is normal for moisture and or frost to form on the Suction Line Accumulator and on the suction line to the Compressor This moisture and or
31. warrants this Dole Sequential Blower Unit to be well made of good material and free from defects It is guaranteed against any defect in material or workmanship for the following period of time providing if claimed defective the sequential Defrost Blower Unit or any part thereof is returned to the Company transportation charges prepaid Sequential Defrost Blower Unit Models FAN MOTORS amp VOLTAGE CONVERSION UNIT 90 DAYS BALANCE OF UNIT 1 YEAR PLATES 5 YEARS If Dole Plates should prove defective after TWO years and prior to the lapse of THREE years the Company will replace said Dole Truck Plate for 4596 of prices in effect at time of exchange and if said Dole Plate shall become defective at the end of THREE years and prior to the lapse of FOUR years the Company will replace said Dole Plate for 6096 of prices in effect at time of exchange and if said Dole Plate shall become defective at the end of FOUR years and prior to the lapse of FIVE years the Company will replace said Dole Plate for 75 of prices in effect at time of exchange The Company shall not be liable for any damage of any nature caused by defects in workmanship or material or for any other reason but is liability shall be limited to the value of the Dole Sequential Defrost Blower Unit guaranteed and correction of any defects in workmanship or material shall constitute a fulfillment of its guarantee The Company s liability in all events shall be limited to replacing or
32. y when a truck returns to a distribution point and is connected to external power for recharging the system will be in the refrigerate mode Unless the Manual Initiate Switch is depressed momentarily all plates will undergo refrigeration When SW1 is depressed the Defrost light P2 should come on If the light is not on the following steps should be taken to troubleshoot this condition 1 Check to determine if P2 is defective 2 If P2 is not defective check status of R4 Relay When SW1 is depressed the normally open contact of R4 should close 3 If R4 is not defective check status of Cycle Timer M2 With SW1 depressed momentarily the timer cams should rotate approximately 120 degrees 90 degrees in 4plate units If cams do not rotate see Troubleshooting Cycle Timer will not advance 4 f Cycle Timer is not defective check status of the Latching Relay LR With SW1 depressed the LR contacts between 4 amp 7 wire 20 amp 37 and between 6 amp 9 wire LI amp 32 should be open If they are closed check for an open circuit across the primary of Transformer XFMR2 If 230VAC is present across the transformer check for 115VAC across the Secondary Transformer checks out the latching relay LR should be replaced Troubleshooting Ice buildup on plates Ice buildup on plates can result from many causes Each should be investigated Check for the following 1 Check for a clear sight glass during the defrost cycle
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