TECHNICAL & SERVICE MANUAL
Contents
1. 08 18 154 169 _ 61 14 924 34 30 856 20 165 048 Circuit Board Confirm the thermistor is operating properly before troubleshooting the circuit board Make sure the control board has 24 Volts AC when measured at the 24 VAC and the com terminals If not find the cause of voltage failure The circuit board is designed to convert the thermistor ohm input to a 2 9 16 VDC output to control the position of the damper actuator Above 2 VDC output the actuator will start to move the damper toward the closed position At 9 16 VDC the actuator will have moved 85 degrees and the damper will be approximately 95 closed The damper should never be 100 closed The chart below includes the various damper angles based on the different outdoor temperatures Measure the DC voltage output on the circuit board at com and the out terminals If the output doesn t match the thermistor input ohms as shown below replace the circuit board Outdoor Thermistor Control board Damper Temperature Ohms DC volts output Angle Above 52 F N A 2 00 0 full open o 52 18 873 2 00 0 Below 20 F N A Transformer 2013 Mitsubishi Electric US Inc The transformer is 208 230 24volt AC For proper connections to the outdoor unit the following diagram and instructions should be referred to Outdoor Unit Control Board CNAC2 Connection 230 460v wh 208v or f Insert the black2. 2013 TECHNICAL amp SERVICE MANUAL wa LAHK 1 Low Ambient Hood For use with CITY MULTI PUHY P T Y S KMU PURY P T Y S KMU and PURY HP T Y S KMU Series outdoor units lb Listeo Intertek 4000292 Manufactured for Mitsubishi Electric US Inc December 2013 p 2013 Mitsubishi Electric US Inc LAHK 1 Control Box Component Identification DAMPER CONTROL BOX CONTROL BOARD TRANSFORMER 208 230 24VAC 40VA INTERLOCK RELAY SPDT 240 VOLT COIL TERMINAL BLOCK DAMPER ACTUATOR T on WITH PLASTIC SHIELD Operating Sequence Outdoor Unit in Heating Mode Heating mode requires the damper be in the fully open Outdoor Unit in Cooling Mode position to allow full airflow and maximum heating The LAHK 1 low ambient hood is designed to reduce Capacity the airflow through the outdoor units as the ambient Heating mode automatically deactivates the kit through temperature drops This maintains the head pressure an interlock relay The coil for this relay is tied into the at a level that will allow the system to perform at 100 reversing valve connection on the outdoor unit When Capacity down to 10 F outdoor temperature the unit switches to heating mode the reversing valve is energized This in turn energizes the interlock relay A thermistor mounted on the side of the unit senses When the relay is energized the normally closed the outdoor temperature As the outdoor temperature contact opens By opening this c
3. A Inc 2 pe Gur wires onta We sia COMmeelOrl j Manufactured for Mitsubishi Electric US Inc December 2013 2013 Mitsubishi Electric US Inc
4. Electric US Inc Wiring Diagram LAHK 1 Wiring Diagram Control Box Mounted on Hood l l green 40 VA i o Ground Transformer l orange 208v Damper Actuator l 230V R e sliti Common l 24 V Com c Hot j 5 white i 240 volt ac 2 10VDC NC Relay blue Circuit Board Factory switch positions CNAC2 Connection Ik so common blk FET black D 230 460v wh white 208v or Insert the black plug into the CNAC2 connection E on the board Connect the white wire male F connector to the wire that corresponds to the outdoor unit supply voltage as shown below move and secure cap to unused wire 208 volt orange wire female connector Low Ambient Hood Part Number LAHK 1 Supply Voltage _208 230V 1 phase 60Hz Amps 0 20 Fuse Size 1 amp i a ae ee 230 460 volt white wire female connector For use with Modular PURY and PUHY CN505 Connection l outdoor units T Y S KMU Series Only To reversing valve 21S4a e Serial Number CN505 6 5 4 3 2 1 Initials Disconnect white plug with four wires from l l l l the CN505 connection Plug the white l l l l l l l l l l l l l l l l l l l Date of Manufacture l l l l l l l l Manufactured for Mitsubishi Electric and l l l e male connector from the low ambient kit onto green the CN505 connection Connect the white Electronics US
5. means Blink s Thermistor Temperature Above 50F 50F to 20F SEHK 3 Below 20F Constant ON Thermistor is open or shorted If the light is on constantly the thermistor is open or shorted and needs to be replaced If the blinking light sequence doesn t fall within the range given in the December 2013 chart the thermistor needs to be replaced If it s suspected that the thermistor is operating inaccurately check the tolerance in the following instructions Disconnect the thermistor from the control board Measure the resistance across the two leads Measure the temperature of the thermistor Accuracy on the temperature reading is important to prevent a good thermistor from being replaced Compare the ohm reading with the temperature on the chart below Based on the thermistor temperature the ohm reading should be within 1 2 of the number shown below If not and the thermistor connections are not corroded the thermistor should be replaced F Ohms F Ohms F Ohms F Ohms _ 86 8 056 59 15 714 32 32650 5 72 906 _ 84 8448 30 34 562 3 77 620 82 8862 55 17438 28 36 601 1 82 676 81 9077 54 17 902 0 85 340 52 18 873 26 38 776 2 90 962 50 19 903 23 42 315 4 96 999 48 20997 21 44 875 103 486 46 22 159 19 47 610 110 460 114 141 7 64 13 822 10 62 460 _ 63 14 179 36 291171 9 64 4
6. ontact the power to drops the resistance of the thermistor increases The the transformer and control board is interrupted this thermistor is connected to the specially designed circuit allows the damper to spring to the full open position board and the resistance value from the thermistor is converted to a DC voltage output within the circuit Outdoor Unit in Defrost Mode board This DC voltage output drives the damper If the outdoor unit will be running in heating mode a actuator to a predetermined position based on the defrost period is inevitable During defrost the low outdoor temperature ambient controls see this as the unit operating in The inverter driven fan motor will adjust the discharge cooling mode If the outdoor temperature is below 50 F pressure based on system capacity demand The the damper will close to a position equal to that motor will speed up and force more air through the required during the cooling cycle Once the unit comes damper if there is a higher system capacity demand or back out of defrost and into heating mode the damper slow down if system capacity demand decreases will again spring wide open for full airflow Operation Test Outdoor unit must be in cooling mode December 2013 2 2013 Mitsubishi Electric US Inc All hoods and damper controls are tested at the factory before shipping To perform an operational test once the installation has been completed follow the steps below Operation testing when
7. plug into the CNAC2 connection on the board Connect the white wire male l 7 connector to the wire that corresponds to the outdoor unit supply voltage as shown below l l oe a a a ao am ao am an ao am o a o a l move and secure cap to unused wire l 208 volt orange wire female connector i The low ambient kit is designed to function with both 208 230 volt and also 460 volt outdoor units On 208 volt units the CNAC2 connector will provide 208 volts to the control transformer On 230 volt units the CNAC2 connector will provide 230 volts to the control transformer The 460 volt units include a transformer that reduces the outdoor unit internal voltage to 230 volts Because of this on the 460 volt units the CNAC2 connector will also provide 230 volts to the control transformer Once the proper connection is confirmed measure voltage on the primary side of the transformer It should be 208 or 230 10 depending on the supply voltage at the outdoor unit If there is no voltage on the primary side of the transformer check the fuse that is located in the fuse holder inside the outdoor unit See wiring diagram for fuse location Once power has been confirmed at the primary side of the transformer check the secondary low voltage side of the transformer it should be approximately 27 volts If no voltage is present replace transformer Interlock Relay The interlock relay uses a normally closed contact to allow power to flo
8. r manually positioning and locking the damper in place IMPORTANT Disconnect power to the damper motor before locking in place The damper actuator comes with a crank handle attached to manually move the damper position The crank handle is removable and if it s missing a 3 16 allen wrench will work just as well December 2013 Use the following diagrams and instructions for this procedure a 4 j i gt J SA aa E Se o f y J O x Winding the damper actuator insert crank handle turn handle in direction of arrow Locking the damper actuator Flip the lock switch to the position pointing to the locked symbol Unlocking the damper actuator 2 options Flip the lock switch to the position pointing to the unlocked symbol Remote control by supplying power to the unit for gt than 3 sec 2013 Mitsubishi Electric US Inc Angle Indicator LAHK 1 Parts List Damper Control Box Interlock Relay 240 volt coil CN505 Connector Part Number HC LAHK 1 1A Includes everything shown CNAC2 Connector Part Number HC LAHK 1 2A Includes everything shown Note Damper linkage parts can be purchased locally If damper blades or complete assembly needs replacing order new LAHK 2 hood and damper assembly Manufactured for Mitsubishi Electric and Electronics USA December 2013 2013 Mitsubishi
9. rect position 0 Degrees IMPORTANT It s possible that during shipping the damper shaft may have moved in the actuator shaft clamp assembly With power off make sure the damper is in the full open position 0 degrees If necessary loosen the shaft clamp on the actuator move the damper to the 100 open position and re clamp tightly If the damper actuator angle doesn t match within 2 with the corresponding control board voltage supplied as shown below the damper actuator should be replaced Outdoor Thermistor Control board Damper Temperature Ohms DC volts output Angle Above 52 F 0 full open 2013 Mitsubishi Electric US Inc Damper Actuator Manual Override IMPORTANT Never manually override the damper position if the outdoor unit could switch to heating mode during the override period Heating mode requires the damper to be fully open for full Capacity It may be desirable to manually override the damper position and lock it into position until repairs can be completed If so select an average temperature typical for the outside environment during the override period and then use that average temperature to find the desired damper angle in the chart below Temperature Ohms DC volts output Angle 528 873 20 50 f so 385 w O Oo B z a Ot 3 3o00 7o e 3 3e 7 7 5 sar 875 fo e 2 seo s6 amp Follow the instructions below fo
10. the outdoor ambient is ABOVE 50 F Turn on power to the outdoor unit 1 2 Make sure the outdoor unit is in cooling mode 3 Locate the outdoor temperature sensing thermistor at the end of the short conduit coming out the side of the control panel it can be seen inside the plastic shield 4 Using an aerosol dusting sprayer invert the can and spray the thermistor with very short bursts of the cold liquid Caution Do Not overspray the thermistor as it could be damaged It may take 10 20 seconds for the internal thermistor temperature to drop The damper will start to move toward the closed position after the thermistor drops below 50 F 5 Once the thermistor warms above 50 F it will move back to the full open position indicating the low ambient kit is working as designed Operation testing when the outdoor ambient is BELOW 50 F Turn on power to the outdoor unit 1 2 Make sure the outdoor unit is in cooling mode 3 The damper will move toward the closed position to a predetermined position based on the outdoor ambient temperature indicating the low ambient kit is working as designed If neither of these tests work Proceed with the component troubleshooting instructions Component Troubleshooting Thermistor The thermistor is a 10 000 Q NTC Type The circuit board has a blinking indicator light built in to reference what the thermistor is sensing The chart below shows what the blinking light sequence
11. w to the transformer energizing the low ambient kit control circuitry Any time the outdoor unit is in cooling mode this contact will be in closed When the outdoor unit reversing valves energizes switches to heating mode the coil of the relay is energized opening this contact This in turn de energizes the transformer disconnecting power to the low ambient kit control circuitry This allows the damper to spring return to the full open position during heating mode To check make sure the contact is closed when the outdoor unit is in cooling mode coil de energized and the contact is open when the outdoor unit is in the heating mode coil energized December 2013 Damper Actuator Before trouble shooting the damper motor verify the two factory switches are in the position shown below Damper Actuator Common Hot 2 10VDC Factory switch positions Make sure the motor has 24 volts on the 1 Common and 2 Hot connections If not find the cause of the voltage failure and correct The damper actuator receives a DC voltage signal from the circuit board This voltage can be measured between 1 Common and 3 2 10VDC connections The damper actuator has an angle indicator where it clamps onto the damper shaft linkage Compare the DC voltage supply to the damper angle indicator position in the chart below The angle should be within 2 of the chart shown below If not check to make sure the damper started off in the cor
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