Mars Comfort-Aire VMH Series Service Manual
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Mars Comfort-Aire VMH Series Service Manual

Inverter multi zone ductless mini-split
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Service Manual
VMH Series
Inverter Multi Zone Ductless Mini-Split
Model
A-VMH18DU-1
A-VMH28TU-1
A-VMH36QU-1
A-VMH48PU-1
www.marsdelivers.com

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Summary of Contents for Mars Comfort-Aire VMH Series

  • Page 1 Service Manual VMH Series Inverter Multi Zone Ductless Mini-Split Model A-VMH18DU-1 A-VMH28TU-1 A-VMH36QU-1 A-VMH48PU-1 www.marsdelivers.com...

  • Page 2: Table Of Contents

    Service Manual - VMH 18/28/36/48 Series CONTENTS Indoor Unit Combination ............................4 Dimension Of Outdoor Unit ............................ 7 Refrigerant Cycle Diagram ............................9 Installation Details ..............................12 4.1 Wrench torque sheet for installation ....................... 12 4.2 Connecting the cables ............................12 4.3 Pipe length and the elevation ...........................
  • Page 3 Service Manual - VMH 18/28/36/48 Series  A-VMH28TU-1 .............................. 135  A-VMH36QU-1, A-VMH48PU-1 ......................... 143  A-VMH36QU-1, A-VMH48PU-1 ......................... 150...

  • Page 4: Indoor Unit Combination

    Service Manual - VMH 18/28/36/48 Series Indoor Unit Combination Multi DC Outdoor Nominal Suggested Limit Unit capacity Combination 6+12 A-VMH18DU-1 5.2kW None 9+12 12+12 Suggested Combination Multi DC Outdoor Nominal Limit Unit capacity Two units Three units 6+12 6+6+6 6+12+12 6+18 6+6+9 6+12+18...
  • Page 5 Service Manual - VMH 18/28/36/48 Series Suggested Combination Multi DC Outdoor Unit Nominal capacity Limit Two units Three units Four units 6+18 6+6+12 9+9+12 6+6+6+6 6+9+9+18 6+24 6+6+18 9+9+18 6+6+6+9 6+9+9+24 9+18 6+6+24 9+9+24 6+6+6+12 6+9+12+12 9+24 6+9+12 9+12+12 6+6+6+18 6+9+12+18 12+12 6+9+18...
  • Page 6 Service Manual - VMH 18/28/36/48 Series Suggested Combination Multi DC Nominal Limit Outdoor Unit capacity Three units Four units Five units units 9+24 6+6+24 9+12+18 6+6+6+18 6+9+18+30 6+6+6+6+9 6+6+12+12+12 9+30 6+6+6+24 6+12+12+12 6+6+6+6+12 6+6+12+12+18 6+6+30 9+12+24 9+36 6+6+6+30 6+12+12+18 6+6+6+6+18 6+6+12+12+24 6+6+36 9+12+30...

  • Page 7: Dimension Of Outdoor Unit

    Service Manual - VMH 18/28/36/48 Series Dimension Of Outdoor Unit Model Unit A-VMH18DU-1 inch 33.3 14.3 27.6 36.0 21.3 13.8 A-VMH18DU-1 inch 35.04 13.46 26.50 38.98 26.10 13.94 1034 A-VMH28TU-1 inch 37.2 16.5 31.9 40.6 26.5 15.9 1034 A-VMH36QU-1 A-VMH48PU-1 inch 37.2 16.5...
  • Page 8 Service Manual - VMH 18/28/36/48 Series Unit Model 1333 1060 A-VMH36QU-1 A-VMH48PU-1 inch 37.5 16.3 52.5 41.7 25.0 15.9...

  • Page 9: Refrigerant Cycle Diagram

    Service Manual - VMH 18/28/36/48 Series Refrigerant Cycle Diagram 3.1 Refrigeration circuit drawing of A-VMH18DU-1 INDOOR OUTDOOR EXV A LIQUID VALVE A EXV B LIQUID VALVE B CAPILLARY TUBE Condenser temp. sensor HEAT EXCHANGE HEAT T1 Room T4 Ambient (EVAPORATOR) EXCHANGE temp.
  • Page 10 Service Manual - VMH 18/28/36/48 Series 3.3 Refrigeration circuit drawing A-VMH28TU-1 INDOOR OUTDOOR EXV A LIQUID VALVE A EXV B LIQUID VALVE B CAPILLARY TUBE EXV C LIQUID VALVE C Condenser temp. sensor HEAT EXCHANGE HEAT T1 Room T4 Ambient (EVAPORATOR) EXCHANGE temp.
  • Page 11 Service Manual - VMH 18/28/36/48 Series 3.6 Refrigeration circuit drawing of A-VMH48PU-1 INDOOR OUTDOOR EXV A LIQUID VALVE A EXV B LIQUID VALVE B Radiator for IPM Plate heat EXV G exchanger EXV F EXV C LIQUID VALVE C EXV D LIQUID VALVE D Condenser temp.

  • Page 12: Installation Details

    Service Manual - VMH 18/28/36/48 Series Caution: Installation Details ● Refrigerant pipe diameter different 4.1 Wrench torque sheet for installation according to indoor unit to be connected. When using the extension pipe, refer to the tables below. Outside diameter Torque Additional tightening torque inch N.cm...
  • Page 13 Service Manual - VMH 18/28/36/48 Series 1. Air Purging Using the Vacuum Pump 2. Adding refrigerant if the pipe length exceeds chargeless pipe length Procedure: 1) Connect the charge hose to the charging cylinder and open the 2-way and 3-way valves. 1.

  • Page 14: Adding Refrigerant After Long-Term System Operation

    Service Manual - VMH 18/28/36/48 Series 4.5 Adding Refrigerant after Long-Term 4.6 Procedure when servicing the indoor System Operation unit refrigeration circuit. 1. Collecting the refrigerant into the outdoor unit Procedure 1) Connect the charge hose to the 3-way service port and open the 2-way and 3-way valve.

  • Page 15: Evacuation After Servicing The Outdoor Unit Refrigeration Circuit

    Service Manual - VMH 18/28/36/48 Series 2. Air purging with vacuum pump 4.7 Evacuation after servicing the outdoor unit refrigeration circuit 1. Evacuation of the complete refrigeration circuit, Indoor and outdoor unit. 1) Completely tighten the flare nuts of the indoor and outdoor units, confirm that both the 2-way Procedure: and 3-way valves are set to the closed...
  • Page 16 Service Manual - VMH 18/28/36/48 Series of the cylinder. If the refrigerant is R410A, make the cylinder bottom up to ensure liquid charge. 2). Purge the air from the charge hose Open the valve at the bottom of the cylinder and press the check valve on the charge set to purge the air (be careful of the liquid refrigerant).

  • Page 17: Electronic Function

    Service Manual - VMH 18/28/36/48 Series 5.3.3 Fan Speed Malfunction 5. Electronic Function ---- If outdoor fan speed is lower than 100RPM higher than 2400RPM for 60 seconds or more, 5.1 Abbreviation the unit stops and LED displays failure code. T1: Indoor ambient temperature 5.3.4 Inverter Module Protection.
  • Page 18 Service Manual - VMH 18/28/36/48 Series Cooling mode: The difference between current limits H H e e a a t t R R e e t t u u r r n n I I and shutdown current T4≥15℃ H H e e a a t t T T 4 4 Z Z o o n n e e 4 4 I I Heating current limit value C C o o o o l l T T 4 4 Z Z o o n n e e 5 5 I I...

  • Page 19: Control And Functions

    Service Manual - VMH 18/28/36/48 Series Use the following table and final capacity request to confirm the operating frequency. 5.3.11 Low Outdoor Ambient Temperature Protection … COOL When the compressor is off and T4 is lower than - Frequency (Hz) L_F2 L_F1 L_F2...
  • Page 20 Service Manual - VMH 18/28/36/48 Series Model ℃ Note: The final result is an integer. Standby Then modify it according to a T2 average (correction): Fmax=T4FREHEATMAX1 Fmax=T4FREHEATMAX2 Note: Average value of T2：Sum T2 value of all (indoor units) / (indoor units’ number) Fmax=T4FREHEATMAX3 ℃...
  • Page 21 Service Manual - VMH 18/28/36/48 Series Defrost Stop Conditions ℃ If any one of the following conditions is satisfied, Supper high fan speed defrosting ends and the unit returns to normal heating mode: High fan speed ----T3 rises above than TCDE1℃. Middle fan speed Low fan speed ----T3 remains at TCDE2℃...
  • Page 22 Service Manual - VMH 18/28/36/48 Series maintains 0P, and the cooling mode opens to the initial cooling opening). The EVI valve opens T3/°C 510P first, then 530P, then the counter is cleared Increase fan speed to 0P. LowCoolT3_ON 2. After the compressor is stopped, keep 2.1 If the EVI valve has a valve opening action before the stop, the PMV_CLOSE_EE step is...
  • Page 23 Service Manual - VMH 18/28/36/48 Series demand and T2B information and then calculates compressor has been off for 2 consecutive their average. After comparing each indoor’s T2B minutes. with the average, the outdoor gives the following Failure or protection (excluding discharge modification commands: temperature protection and high/low pressure protection) causes the four-way valve to...

  • Page 24: Wiring Diagrams

    Service Manual - VMH 18/28/36/48 Series Wiring Diagrams 6.1 Wiring diagram of 1 drive 2 outdoor A-VMH18DU-1...
  • Page 25 Service Manual - VMH 18/28/36/48 Series 6.2 Wiring diagram of 1 drive 3 outdoor A-VMH28TU-1...
  • Page 26 Service Manual - VMH 18/28/36/48 Series 6.3 Wiring diagram of 1 drive 4 outdoor A-VMH36QU-1...
  • Page 27 Service Manual - VMH 18/28/36/48 Series 6.4 Wiring diagram of 1 drive 5 outdoor A-VMH48PU-1...
  • Page 28 Service Manual - VMH 18/28/36/48 Series PCB board of A-VMH18DU-1, A-VMH28TU-1, A-VMH36QU-1 Name Meaning T3: condenser temperature sensor T3/T4 CN17 T4: outdoor ambient temperature sensor connect to discharge sensor TESTPORT CN26 connect to DR board CN1 LOW/HIGH CN14 Red: low pressure protect...
  • Page 29 Service Manual - VMH 18/28/36/48 Series Yellow: high pressure protect Comp Top CN12 compressor top temperature sensor L-OUT L-OUT connect to IPM board CN4 N-OUT N-OUT connect to IPM board CN5 CN32 CN32 connect to DR board CN5 CN33 CN33 connect to DR board CN5 N-in N_in: connect to N-line (208-230V AC input)
  • Page 30 Service Manual - VMH 18/28/36/48 Series IPM board of A-VMH18DU-1, A-VMH28TU-1, A-VMH36QU-1 Name Meaning connect to main board L-Out connect to main board N-Out CN_Reactor CN2/CN3 connect to reactor CN_COMP CN_COMP connect to compressor connect to main board CN21 AN_DC CN14 connect to outdoor DC fan...
  • Page 31 Service Manual - VMH 18/28/36/48 Series PCB board of A-VMH18DU-1 Name Meaning CN11 L_in: connect to N-line (208-230V AC input) Power Supply CN12 N_in: connect to L-line (208-230V AC input) connect to Electric Expansion Valve A Electronic connect to Electric Expansion Valve B Expansion CN34 connect to Electric Expansion Valve C...
  • Page 32 Service Manual - VMH 18/28/36/48 Series connect to pipe temp. sensor T3, ambient temp. sensor T4, exhaust T3 T4 TP CN26 temp. sensor TP OLP TEMP. CN30 connect to compressor top temp. sensor (5VDC Pulse wave) SENSOR connect to high- and low-pressure switch (pin1-pin2&pin3-pin4:5VDC H-PRO, L- CN29 pulse wave)
  • Page 33 Service Manual - VMH 18/28/36/48 Series PCB board of A-VMH28TU-1, A-VMH36QU-1 Name Meaning Current loop communication A, signal wire, connect to the terminal (24V CN30 DC Pulse wave) Current loop communication B, signal wire, connect to the terminal (24V CN29 DC Pulse wave) Current loop communication C, signal wire, connect to the terminal (24V CN28...
  • Page 34 Service Manual - VMH 18/28/36/48 Series DC Pulse wave) Current loop communication E, signal wire, connect to the terminal (24V CN26 DC Pulse wave) L-IN Power supply, connect to the terminal (208-230V AC) N-IN TESTPORT CONdebug connect to detector Fuse Fuse 1 Fuse T30A/250V Digital display button...
  • Page 35 Service Manual - VMH 18/28/36/48 Series IPM board of A-VMH28TU-1, A-VMH36QU-1 Name Meaning OUT FAN CN19 (DC) Connect to DC motor Connect to compressor W Connect to compressor V Connect to compressor U CN54 CN54 Connect to main PCB CN6 CN51 CN51 Connect to PFC inductor...
  • Page 36 Service Manual - VMH 18/28/36/48 Series CN53 CN53 Connect to main PCB CN5 CN52 CN52 Connect to PFC inductor CN55 CN55 Connect to main PCB CN7...
  • Page 37 Service Manual - VMH 18/28/36/48 Series PCB board of A-VMH36QU-1, A-VMH48PU-1...
  • Page 38 Service Manual - VMH 18/28/36/48 Series Name Meaning N_in: connect to N-line (208-230V AC input) Power Supply L_in: connect to L-line (208-230V AC input) CN13 CN16 CN21 CN29 S: connect to indoor unit communication (pin1-pin2: 24VDC Pulse wave; CN39 pin2-pin3: 208-230V AC input) HEAT_D CN19/CN20 connect to the heater, 208-230V AC when is ON...
  • Page 39 Service Manual - VMH 18/28/36/48 Series INDOOR PIPE CN11 OUT TEMP connect to evaporator coil outlet temperature sensor T2B TESTPORT CN35 used for testing connect to IPM board CN22 CN22 485 communication connect to IPM board (208-230V AC input) IPM board of A-VMH36QU-1, A-VMH48PU-1...
  • Page 40 Service Manual - VMH 18/28/36/48 Series Name Meaning Connect to compressor 0V AC (standby) 10-200V AC (running) Connect to main PCB FAN1 CN11 connect to DC motor driver board FAN2 PFC-L1 connect to reactor PFC-L2 PFC-L1 connect to bridge PFC-L2...
  • Page 41 Service Manual - VMH 18/28/36/48 Series PCB Board of A-VMH48PU-1...
  • Page 42 Service Manual - VMH 18/28/36/48 Series Name Meaning L1_in: connect to L1-line (230V AC input) Power Supply L2_in: connect to L2-line (230V AC input) Exhaust temp. sensor TP TESTPORT CN35 used for testing HEAT1 CN19/CN20 connect to chassis heater, 208-230V AC when is ON HEAT2 CN24/CN25 connect to compressor heater, 208-230V AC when is ON...
  • Page 43 Service Manual - VMH 18/28/36/48 Series IPM board of A-VMH48PU-1...
  • Page 44 Service Manual - VMH 18/28/36/48 Series Name Meaning connect to main board L-Out Power Supply connect to main board N-Out Connect to main PCB CN6 FAN_DC FAN_1/FAN_2 connect to outdoor DC fan 1& DC fan 2 CN_COMP Connect to compressor...

  • Page 45: Troubleshooting

    Service Manual - VMH 18/28/36/48 Series Troubleshooting 7.1Safety Electricity is stored in capacitors, even when the power supply is shut off. Do not forget to discharge the electricity in the capacitors. The value of resistance is about 1500 ohm to 2000 ohm Electrolytic Capacitors (HIGH VOLTAGE! CAUTION!) Bulb (25-40W)

  • Page 46: Indoor Unit Error Display

    Service Manual - VMH 18/28/36/48 Series 7.2 Indoor Unit Error Display For Old Console series B-VMH12FU-1; Operation Timer De-frost Failure Indoor room temperature sensor (T1) malfunction ★ Evaporator coil temperature sensor (T2) malfunction ★ Communication malfunction between indoor and outdoor units ★...
  • Page 47 Service Manual - VMH 18/28/36/48 Series Indoor unit EEPROM parameter error —— ★ ★ Inverter module (IPM) malfunction  ★ Outdoor temperature sensor (coil sensor T3 or ambient temperature E0,E4 ★  sensor T4) malfunction or Outdoor unit EEPROM parameter error Outdoor fan speed malfunction ...

  • Page 48: Outdoor Unit Display

    Service Manual - VMH 18/28/36/48 Series Communication malfunction between Cassette optional lift panel —— ★ 8 times  and the unit. —— ★ 9 times Cassette optional lift panel malfunction  —— ★ 10 times Cassette optional lift panel not closed ...
  • Page 49 Service Manual - VMH 18/28/36/48 Series Display Remark Number Presses Normal display Displays running frequency, running state, or malfunction code Quantity of indoor units with working connection Actual data Display Number of indoor units Outdoor unit running mode code Off: 0, Fan only: 1, Cooling: 2, Heating: 3, Forced cooling: 4. Forced defrost: A Indoor unit A capacity Indoor unit B capacity...
  • Page 50 Service Manual - VMH 18/28/36/48 Series units' amendatory capacity demand The frequency after the frequency limit The frequency sending to compressor control chip Indoor unit A evaporator outlet temperature (T Indoor unit B evaporator outlet temperature (T ℃ If the temperature is lower than -9 , the digital display shows “-9.”...
  • Page 51 Service Manual - VMH 18/28/36/48 Series F indoor unit evaporator outlet temperature (T F indoor unit room temperature (T F indoor unit evaporator temperature (T EXV open angle for F indoor unit Reason of stop EVI valve target angle (only for Actual data/4.
  • Page 52 Service Manual - VMH 18/28/36/48 Series Indoor unit C capacity demand code Indoor unit D capacity demand code Indoor unit E capacity demand code Outdoor unit amendatory capacity demand code The frequency corresponding to the total indoor units' amendatory capacity demand The frequency after the frequency limit The frequency sending to compressor control chip...
  • Page 53 Service Manual - VMH 18/28/36/48 Series Bit1 may be caused Frequency limit caused by T3 by current, IPM Bit0 Frequency limit caused by T2 or T3. T2B fault 00: No fault,01: T2B-A fault, ,02: T2B-B fault ,03: T2B-C fault,04: T2B-D fault, 05: T2B-E fault, 06: T2B-F fault (The display priority is A-B-C-D-E-F) Average value of T2 (Sum T2 value of all indoor units) / (number of indoor units in good...

  • Page 54: Diagnosis And Solution

    Service Manual - VMH 18/28/36/48 Series 7.4 Diagnosis and Solution 7.4.1 Indoor unit trouble shooting 7.4.1.1 Indoor unit EEPROM parameter error diagnosis and solution. Malfunction conditions Indoor or outdoor PCB main chip does not receive feedback from EEPROM chip. Potential causes Installation mistake ●...
  • Page 55 Service Manual - VMH 18/28/36/48 Series 7.4.1.2 Communication malfunction between indoor and outdoor units’ diagnosis and solution. Malfunction conditions If indoor unit does not receive the feedback from outdoor unit for 120 seconds. Potential causes ● Wiring mistake ● Faulty indoor or outdoor PCB Trouble shooting:...
  • Page 56 Service Manual - VMH 18/28/36/48 Series Indoor / outdoor units communication error Start: Power off , then Power on the A/C by the Breaker. (reconnect the power wire). Is it still displaying the error code? Check wiring on the outdoor and indoor terminal follow the wiring diagram.
  • Page 57 Service Manual - VMH 18/28/36/48 Series Pic 1: Use a multimeter to test the DC voltage between 2(old: L2) port and S port of outdoor unit. The red pin of multimeter connects with 2 (old: L2) port while the black pin is for S port.
  • Page 58 Service Manual - VMH 18/28/36/48 Series Pic 2: IPM (for 2 zone/ 3-zone) Operating Standby...
  • Page 59 Service Manual - VMH 18/28/36/48 Series Pic 2: IPM (for 4 zone & 5 zone) Operating Standby Power PIC3: Main board LED when power on and unit standby.
  • Page 60 Service Manual - VMH 18/28/36/48 Series PIC 4: Check point button, press 1 time for check how many indoor units are connected. 7.4.1.3 Zero-crossing signal detection error diagnosis and solution. Malfunction conditions When PCB does not receive zero crossing signal feedback for 4 minutes or the zero-crossing signal time interval is abnormal.
  • Page 61 Service Manual - VMH 18/28/36/48 Series 7.4.1.4 Indoor fan speed malfunction diagnosis and solution. Malfunction conditions When indoor fan speed is too low (300RPM) for a certain period of time, the unit ceases operation and the LED displays a failure code. Wiring mistake Potential causes ●...
  • Page 62 Service Manual - VMH 18/28/36/48 Series Index 1: 1: Indoor AC fan motor Power on and set the unit running in fan mode at high fan speed. After running for 15 seconds, measure the voltage of pin1 and pin2. If the value of the voltage is less than 100V (208~240V power supply) or 50V (115V power supply), the PCB must have problems and need to be replaced.
  • Page 63 Service Manual - VMH 18/28/36/48 Series 7.4.1.5 Temperature sensor malfunction diagnosis and solution. Malfunction conditions If the sampling voltage is lower than 0.06V or higher than 4.94V, the LED displays a failure. Potential causes Wiring mistake ● Faulty sensor ● Faulty PCB ●...
  • Page 64 Service Manual - VMH 18/28/36/48 Series 7.4.1.6 Inverter module (IPM) malfunction diagnosis and solution. Malfunction conditions When the voltage signal that IPM send to compressor drive chip is abnormal, the display LED will show “P6”, and AC will turn off. Potential causes ●...
  • Page 65 Service Manual - VMH 18/28/36/48 Series IPM module protection Check whether the voltage range Check whether the input Regulate it to correct, then of P-N on IPM module is normal? power supply is correct? check whether the system DC277-356V for 18-27KBtu/h; 208-230V, 1N, 60Hz can work normally? DC277-410V for 36K-48KBtu/h...
  • Page 66 Service Manual - VMH 18/28/36/48 Series 7.4.1.7 Over-voltage or under-voltage protection diagnosis and solution. Outdoor unit low AC voltage protection Outdoor unit main control board DC bus high voltage protection Outdoor unit main control board DC bus high voltage protection /341 MCE error Voltage protection Check the voltage of outdoor unit power supply,...
  • Page 67 Service Manual - VMH 18/28/36/48 Series 7.4.1.8 Compressor drive malfunction diagnosis and solution The trouble shooting is same with one of IPM module protection. Water-level alarm malfunction 7.4.1.9 diagnosis and solution Malfunction conditions If the sampling voltage is not 5V, the LED will display the failure code. Potential causes ●...
  • Page 68 Service Manual - VMH 18/28/36/48 Series 7.4.1.10 Indoor unit’s mode conflict Error Code P5 (old model) or - - (new model) Malfunction conditions The indoor units cannot work cooling mode and heating at same time. Heating mode has a priority. Potential causes ●...
  • Page 69 Service Manual - VMH 18/28/36/48 Series 7.4.1.11 High temperature protection of IPM board diagnosis and solution High temperature protection of IPM High temperature protection of IPM board board Check whether the radiator is Check whether the radiator is Fix the radiator well Fix the radiator well fixed well ? fixed well ?
  • Page 70 Service Manual - VMH 18/28/36/48 Series Communication error between the indoor PCB and display board 7.4.1.12 Power off, then restart the unit after 2 minutes. Does a problem remain? The unit is operating normally Check the wirings and connections Are all the Ensure proper connections connections good? Replace the indoor main PCB...
  • Page 71 Service Manual - VMH 18/28/36/48 Series 7.4.1.13 Refrigerant Leakage Detection Power off, then restart the unit 2 minutes later. Does a problem remain? Put your hands in front of the indoor air outlet. Is there cool air blowing out from Check the T2 sensor.
  • Page 72 Service Manual - VMH 18/28/36/48 Series 7.4.1.14 Communication malfunction between indoor two chips Shut off the power supply and turn it on 2 minutes later. Is it still displaying The unit is operating normally. the error code? Replace the indoor main PCB.
  • Page 73 Service Manual - VMH 18/28/36/48 Series 7.4.2 Outdoor unit trouble shooting 7.4.2.1 E0/ EC 51 (Outdoor unit EEPROM parameter error) diagnosis and solution Error Code E0/ EC 51 Malfunction conditions PCB main chip does not receive feedback from EEPROM chip Potential causes ●...
  • Page 74 Service Manual - VMH 18/28/36/48 Series 7.4.2.2 E2/ EL 01 (Communication malfunction between indoor and outdoor units) diagnosis and solution. Error Code E2/ EL 01 Malfunction Indoor unit does not receive the feedback from outdoor unit for 120 seconds or outdoor unit does not receive the feedback from conditions any one indoor unit for 180 seconds.
  • Page 75 Service Manual - VMH 18/28/36/48 Series Communication malfunction between indoor and outdoor units Start: Power off , then Power on the A/C by the Breaker. (reconnect the power wire). Is it still displaying the error code? Check wiring on the outdoor and indoor terminal follow the wiring diagram.
  • Page 76 Service Manual - VMH 18/28/36/48 Series Pic 1: Use a multimeter to test the DC voltage between 2(old: L2) port and 3 port of outdoor unit. The red pin of multimeter connects with 2 (old: L2) port while the black pin is for 3 port.
  • Page 77 Service Manual - VMH 18/28/36/48 Series Pic 2: IPM board (for 2-zone/ 3-zone) Operating Standby...
  • Page 78 Service Manual - VMH 18/28/36/48 Series Pic 2: IPM (for 4-zone & 5-zone) Operating Standby Power PIC3: Main board LED when power on and unit standby.
  • Page 79 Service Manual - VMH 18/28/36/48 Series PIC 4: Check point button, press 1 time for check how many indoor units are connected.
  • Page 80 Service Manual - VMH 18/28/36/48 Series 7.4.2.3 E3/ PC 40 (Communication malfunction between IPM board and outdoor main control board) diagnosis Error Code E3/ PC 40 Malfunction PCB main chip does not receive feedback from IPM module for 60 seconds. conditions Potential causes ●...
  • Page 81 Service Manual - VMH 18/28/36/48 Series Remark: Use a multimeter to test the DC voltage between black pin and white pin of signal wire. The normal value should be around 5V. Use a multimeter to test the DC voltage between black pin and red pin of signal wire.
  • Page 82 Service Manual - VMH 18/28/36/48 Series 7.4.2.4 E4/EC 50 (Outdoor temperature sensor (coil sensor T3, ambient sensor T4, Compressor discharge sensor T5、 、 indoor coil outlet pipe sensor T2B) malfunction) diagnosis and solution F1/F2/F3/F4/F5 (No. A, B, C, D, E Indoor unit coil outlet temp. sensor malfunction) diagnosis and solution.
  • Page 83 Service Manual - VMH 18/28/36/48 Series 7.4.2.5 E5/ PC 10/PC 11/PC 12 (Over-voltage or under-voltage protection) diagnosis and solution. Error Code E5/ PC 10/PC 11/PC 12 Malfunction conditions An abnormal voltage rise or drop is detected by checking the specified voltage detection circuit. Potential causes ●...
  • Page 84 Service Manual - VMH 18/28/36/48 Series IPM board (for 2-zone /3-zone) Bridge rectifier (for 2-zone/3-zone) Remark: Measure the DC voltage between + and - port. The normal value should be 190V~250V. P (or E1/E2/E3)-N(GND) (for 2-zone/3-zone) Bridge rectifier (for 2-zone/3-zone) IPM Module (for 2-zone/3-zone)
  • Page 85 Service Manual - VMH 18/28/36/48 Series IPM board (for 4-zone)
  • Page 86 Service Manual - VMH 18/28/36/48 Series Bridge rectifier (for 5-zone) Remark: Measure the DC voltage between + and - port. The normal value should be 190V~250V. IPM board (for 5-zone) IPM Module (for 5-zone)
  • Page 87 Service Manual - VMH 18/28/36/48 Series 7.4.2.6 E6/ PC 0F (PFC module protection) error diagnosis and solution. Error Code E6/ PC 0F Malfunction When the voltage signal that PFC sends to main control board is abnormal, the display LED will show “E6”, and AC will turn off. conditions Potential causes ●...
  • Page 88 Service Manual - VMH 18/28/36/48 Series Inductance Two ports of the inductance...
  • Page 89 Service Manual - VMH 18/28/36/48 Series 7.4.2.7 E8/ EC 07 (Outdoor fan speed malfunction)/ EC 71(Over current failure of outdoor DC fan motor) diagnosis and solution Error Code E8/ EC 07/ EC 71 Malfunction conditions When outdoor fan speed keeps too low (300RPM) or too high(2400RPM) for certain time, the unit will stop, and the LED will display the failure.
  • Page 90 Service Manual - VMH 18/28/36/48 Series Index 1: 1. DC fan motor (control chip is inside fan motor)  Power on and when the unit is in standby, measure the voltage of pin1-pin3, pin4-pin3 in fan motor connector. If the value of the voltage is not in the range showing in below table, the PCB must have problems and need to be replaced.
  • Page 91 Service Manual - VMH 18/28/36/48 Series...
  • Page 92 Service Manual - VMH 18/28/36/48 Series 2. DC Fan Motor (control chip is in PCB)  Release the UVW connector. Measure the resistance of U-V, U-W, and V-W. If the resistances are not equal to each other, the fan motor may be experiencing problems and need to be replaced.
  • Page 93 Service Manual - VMH 18/28/36/48 Series 7.4.2.8 P1/PC 30 (High pressure protection) diagnosis and solution. Error Code P1/PC 30 Malfunction conditions If the sampling voltage is not 5V, the LED will display the failure. Potential causes ● Wiring mistake ● Faulty overload protector ●...
  • Page 94 Service Manual - VMH 18/28/36/48 Series High pressure protection High pressure protection Whether the wiring Whether the wiring between the high pressure between the high pressure switch and main control switch and main control Connect it well Connect it well board is connected well or board is connected well or correctly...
  • Page 95 Service Manual - VMH 18/28/36/48 Series...
  • Page 96 Service Manual - VMH 18/28/36/48 Series 7.4.2.9 P2/PC 31 (Low pressure protection) diagnosis and solution. Error Code P2/PC 31 Malfunction conditions If the sampling voltage is not 5V, the LED will display the failure. Potential causes ● Wiring mistake ● Faulty overload protector ●...
  • Page 97 Service Manual - VMH 18/28/36/48 Series Low pressure protection Low pressure protection Whether the wiring Whether the wiring between the low pressure between the low pressure protector and main control protector and main control Connect it well Connect it well board is connected well or board is connected well or correctly...
  • Page 98 Service Manual - VMH 18/28/36/48 Series...
  • Page 99 Service Manual - VMH 18/28/36/48 Series 7.4.2.10 P3/PC 08 (Current overload protection) / PC 44 (Outdoor unit zero speed protection) / PC 46 (Compressor speed has been out of control) / PC 49 (Compressor overcurrent failure) diagnosis and solution. Error Code P3/PC 08/PC 44/PC 46/PC 49 Malfunction conditions If the outdoor current exceeds the current limit value, the LED...
  • Page 100 Service Manual - VMH 18/28/36/48 Series Current protection of compressor Judge 1: Check whether the input current of the power supply wire is more than 15A(18K) (For 27K&hyper heat 18K, it is Replace outdoor main board 18.5A.For 36K&hyper heat 27K, it is 22.5A.For 48K&hyper heat 36K, it is 28A) Check whether the...
  • Page 101 Service Manual - VMH 18/28/36/48 Series...
  • Page 102 Service Manual - VMH 18/28/36/48 Series 7.4.2.11 P4/PC 06 (Temperature protection of compressor discharge) diagnosis and solution. Error Code P4/PC 06 Malfunction conditions When the compressor discharge temperature(T5) is more than 115℃ for 10 seconds, the compressor will stop restart till T5 is less than 90℃. Potential causes ●...
  • Page 103 Service Manual - VMH 18/28/36/48 Series 7.4.2.12 P5/PC 0A (High temperature protection of condenser) diagnosis and solution. Error Code P5/PC 0A Malfunction conditions When outdoor pipe temperature is more than 65°C, the unit will stop, and unit runs again when outdoor pipe temperature is less than 52°C Potential causes ●...
  • Page 104 Service Manual - VMH 18/28/36/48 Series 7.4.2.13 P6/PC 00 (Inverter module (IPM) malfunction) diagnosis and solution. Error Code P6/PC 00 Malfunction conditions When the voltage signal that IPM send to compressor drive chip is abnormal, the display LED will show “P6”, and AC will turn off.
  • Page 105 Service Manual - VMH 18/28/36/48 Series IPM module protection Check whether the voltage range Check whether the input Regulate it to correct, then of P-N on IPM module is normal? power supply is correct? check whether the system DC277-356V for 18-27KBtu/h; 208-230V, 1N, 60Hz can work normally? DC277-410V for 36-48KBtu/h...
  • Page 106 Service Manual - VMH 18/28/36/48 Series 7.4. 2.14 . High temperature protection of compressor top (IDU P2/ODU P0/PC 02) Malfunction decision If the sampling voltage is not 5V, the LED will display the failure. conditions Supposed causes Faulty overload protector ●...
  • Page 107 Service Manual - VMH 18/28/36/48 Series 7.4. 2.15 Lack phase failure of outdoor DC fan motor (EC72) Power off,then restart the unit The unit operates 2 minutes later.Is it still normally displaying the error code Check the wiring of fan motor.Are all the connections Correct the connections good?
  • Page 108 Service Manual - VMH 18/28/36/48 Series 7.4. 2.16 Outdoor compressor lack phase protection (PC43) Power off,then restart the unit The unit operates 2 minutes later.Is it still normally displaying the error code Check both ends of compressor connecting Correct the connections line .Are all the connections good? Check whether the three-...
  • Page 109 Service Manual - VMH 18/28/36/48 Series 7.4. 2.18 The cooling operation or heating operation does not operate. Potential causes ● Faulty 4-way valve Check of 4-way, please refer to part 5 in 9.5 Trouble Criterion of Main Parts. 7.4.2.19 When cooling, heat exchanger of non-operating indoor unit frosts. When heating, non-operating indoor unit get warm.
  • Page 110 Service Manual - VMH 18/28/36/48 Series 7.4.2.17 Communication malfunction between adapter board and outdoor main control board (ODU Ed) Malfunction decision If outdoor PCB does not receive feedback from adapter board. conditions Supposed causes Wiring mistake ● Faulty PCB ● Power off, then restart the unit after 3 minutes.

  • Page 111: Trouble Criterion Of Main Parts

    Service Manual - VMH 18/28/36/48 Series 7.5 Trouble Criterion of Main Parts. 1.Temperature sensor checking Disconnect the temperature sensor from PCB, measure the resistance value with a tester. Temperature Sensors. Room temp. (T1) sensor, Indoor coil temp. (T2) sensor, Outdoor coil temp. (T3) sensor, Outdoor ambient temp.(T4) sensor, Compressor discharge temp.
  • Page 112 Service Manual - VMH 18/28/36/48 Series Appendix 1 Temperature Sensor Resistance Value Table (℃--K) K Ohm K Ohm K Ohm K Ohm ℃ ℃ ℃ ℃ ℃ ℃ ℃ ℃ 115.266 12.6431 2.35774 0.62973 108.146 12.0561 2.27249 0.61148 101.517 11.5000 2.19073 0.59386 96.3423...
  • Page 113 Service Manual - VMH 18/28/36/48 Series Appendix 2 Unit: ℃---K Discharge temp. sensor table 542.7 68.66 13.59 3.702 511.9 65.62 13.11 3.595 62.73 12.65 3.492 455.9 59.98 12.21 3.392 430.5 57.37 11.79 3.296 406.7 54.89 11.38 3.203 384.3 52.53 10.99 3.113 363.3 50.28...
  • Page 114 Service Manual - VMH 18/28/36/48 Series Appendix 3: 10 11 12 13 14 15 16 17 18 19 20 21 22 ℃ 48 50 52 54 56 58 60 62 64 66 68 70 72 ℉ 23 24 25 26 27 28 29 30 31 32 33 34 35 ℃...
  • Page 115 Service Manual - VMH 18/28/36/48 Series 3. IPM continuity check Turn off the power, let the large capacity electrolytic capacitors discharge completely, and dismount the IPM. Use a digital tester to measure the resistance between P and UVWN; UVW and N. Normal Digital tester Normal resistance value...
  • Page 116 Service Manual - VMH 18/28/36/48 Series Position Resistance Value YDK53- YDK70-6FB YDK180-8GB YSK27-4G YSK68-4B YDK45-6B YSK25-6L 6FB(B) 56Ω±8% 24.5Ω±8% 317Ω±8% 145Ω±8% 345Ω±8% 627Ω±8% (20 88.5Ω±8% Black - (20℃) (20℃) (20℃) (20℃) (20℃) (20℃) ℃) 76Ω±8% 19Ω±8% (20 252Ω±8% 88Ω±8% (20 150Ω±8% 374.3Ω±8% 138Ω±8% (20...
  • Page 117 Service Manual - VMH 18/28/36/48 Series 6.EXV check Disconnect the connectors.
  • Page 118 Service Manual - VMH 18/28/36/48 Series Red Brown Blue Orange Yellow White Resistance to EXV coil Color of lead wire Normal Value Red- Blue Red - Yellow About 50Ω Brown - Orange Brown - White...
  • Page 119 Service Manual - VMH 18/28/36/48 Series Red - Blue Brown - Orange Red - Yellow...
  • Page 120 Service Manual - VMH 18/28/36/48 Series Brown - White...

  • Page 121: Disassembly Instructions

    Service Manual - VMH 18/28/36/48 Series Disassembly Instructions Note: This part is for reference, the photos may have slight difference with your machine.  A-VMH18DU-1 (WCA30 metal plate) Part name Procedures Remarks How to remove the fan assembly assembly. 1) Turn off the air conditioner and turn off the power ②...
  • Page 122 Service Manual - VMH 18/28/36/48 Series cover. (3 screws) 6) Remove the cover of electrical control box. ⑦ ⑦ 7) Disconnect the fan motor connector CN14(3p, white) from the IPM board. ⑧ ⑧ 8) Remove the fan motor after unfastening four fixing screws.
  • Page 123 Service Manual - VMH 18/28/36/48 Series Screws of front panel 2) Remove the screws of big handle and remove the big handle. (4 screws) Screws of big handle 3) Remove two screws of Screws of terminal board and seven terminal board screws of right-rear panel and remove the right-rear panel.
  • Page 124 Service Manual - VMH 18/28/36/48 Series Electrical How to remove the electrical parts parts. 1) Perform work of item 1,2. 2) Remove the four screws fixing the IPM board. IPM board PCB board ④ ④ Unfasten the connector of the reactor. Unfasten the connector ③...
  • Page 125 Service Manual - VMH 18/28/36/48 Series CN17:T3/T4 temperature sensor CN15 CN17 CN18/CN19 CN25/CN23 (2p/2p, white) CN7: Discharge temperature sensor (2p, white) CN15:T2B-A, B temperature sensor (2p/2p, white) CN18/CN19: Electronic expansion valve A, B (6p/6p, red/red) CN25/CN23: S-A, S-B (3p/3p, white/white) Wires: CN5/CN6 CN1/CN2...
  • Page 126 Service Manual - VMH 18/28/36/48 Series Compressor How to remove the compressor. 1) Perform work of item 1,2. 2) Remove the cover of electrical control box. 3) Extract refrigerant gas. 4) Remove the sound insulation material and crankcase heating cable. 5) Remove terminal cover of compressor and ⑥...
  • Page 127 Service Manual - VMH 18/28/36/48 Series Reactor How to remove the reactor 1) Perform work of item 2 2) Unfasten the connector between IPM and reactor. 3) Remove three screws of ② ② reactor and remove the reactor. Screws of cover of inductance The 4-way...
  • Page 128 Service Manual - VMH 18/28/36/48 Series How to remove the expansion expansion valve valve 1) Perform work of item 1,2. 2) Remove the electrical parts Expansion valves from item 3. 3) Remove the coils. 4) Detach the welded parts of Coils expansion valves and pipes.
  • Page 129 Service Manual - VMH 18/28/36/48 Series 4) Remove the screws of front Screws of front panel panel and remove the front panel. (7 screws) Screws of front panel 5) Remove the screws of water collector and remove the water collector. (3 screws) Screws of water collector...
  • Page 130 Service Manual - VMH 18/28/36/48 Series Screws of terminal board 6) Remove two screws of terminal board, and 9 screws of right-side panel, and remove the right side panel. Screws of right side board How to remove the fan assembly. assembly 1) Remove the top cover, right side panel and front...
  • Page 131 Service Manual - VMH 18/28/36/48 Series Remove the fan motor after unfastening four fixing screws. How to remove the electrical parts. Electrical parts 1) Perform work of item 1. ② ② 2) Remove 5 screws of the cover of electrical control box cover and remove it.
  • Page 132 Service Manual - VMH 18/28/36/48 Series 6) Remove the support of electronic control box 7) Disconnect the connectors ⑥ and wires connected from PCB and other parts. 8) Disconnect the grounding wire (yellow - green) after ⑧ ⑧ removing the big handle and the right-rear panel.
  • Page 133 Service Manual - VMH 18/28/36/48 Series How to remove the compressor. Compressor 1) Perform work of item 1,2,3. 2) Remove the electrical control box and partition plate. ⑥ ⑥ 3) Extract refrigerant gas. 4) Remove the sound insulation material and crankcase heating cable.
  • Page 134 Service Manual - VMH 18/28/36/48 Series The 4-way How to remove the 4-way valve valve Coil 1) Perform work of item 1,2. 2) Extract refrigerant gas. Welded parts 3) Remove the electrical parts from item 3. 4) Remove fixing screw of the coil and remove the coil.
  • Page 135 Service Manual - VMH 18/28/36/48 Series A-VMH24TU, A-VMH36QU-1 (WD30 metal plate) Part name Procedures Remarks How to remove the panel Screws of Screws of top cover big handle plate. Panel plate Turn off the air conditioner. Turn off the power breaker.
  • Page 136 Service Manual - VMH 18/28/36/48 Series Screws of front panel 12) Remove two screws of terminal board, screws of water collector and fifteen screws of right-rear panel and remove the right-rear panel. Screws of front panel Screws of front panel Screws of right-rear panel...
  • Page 137 Service Manual - VMH 18/28/36/48 Series Screws of terminal board How to remove the fan assembly. assembly 5) Remove the top cover, right front side panel and ② ② front panel from item 1. Step 1~4 6) Remove the hex nut fixing the fan.
  • Page 138 Service Manual - VMH 18/28/36/48 Series 8) Remove the cover of electrical control box cover. 9) Disconnect the fan motor ⑤ ⑤ connector CN14(5p, white) from the IPM board. Remove the fan motor after unfastening four fixing screws. How to remove the electrical ③...
  • Page 139 Service Manual - VMH 18/28/36/48 Series pieces of connection wires and ④ ④ connectors between IPM and PCB. CN1(5p, white) CN14(3p, white) CN3(red or brown) CN5(blue) ⑥ ⑥ Remove the IPM board. Disconnect the connectors and wires connected from PCB and other CN15 CN7 CN17 CN18/CN19/CN22...
  • Page 140 Service Manual - VMH 18/28/36/48 Series expansion valve A, B, C (6p/6p/6p, red/red/red) CN25/CN23/CN20: S-A, S-B, S-C (3p/3p/3p, white/white/white) Wires: CN20 CN1/CN2: 4-way valve (blue - blue) CN23 CN25 CN5/CN6: Crankcase heating cable (red - red) CN3:L1-IN (red) CN4:L2-IN (black) Disconnect the grounding wire (yellow - green) after removing the big handle...
  • Page 141 Service Manual - VMH 18/28/36/48 Series How to remove the compressor. Compressor 9) Perform work of item 1,2,3. 10) Remove the electrical control box and partition plate. ⑥ ⑥ 11) Extract refrigerant gas. 12) Remove the sound insulation material and crankcase heating cable.
  • Page 142 Service Manual - VMH 18/28/36/48 Series Reactor How to remove the reactor 1) Perform work of item 1,2 2) Unfasten the connector between IPM and reactor. 3) Remove two screws of cover of inductance, and remove the cover of Screws of cover of inductance inductance...
  • Page 143 Service Manual - VMH 18/28/36/48 Series How to remove the expansion expansion valve valve 5) Perform work of item 1,2. 6) Remove the electrical parts Expansion valves from item 3. 7) Remove the coils. 8) Detach the welded parts of expansion valves and pipes.
  • Page 144 Service Manual - VMH 18/28/36/48 Series panel and remove the front panel. (8 screws) Screws of front panel Screws of right front side panel Screws of front panel 6) Remove two screws of terminal board, screws of water collector and fifteen Screws of front panel screws of right-rear panel and remove the right-rear...
  • Page 145 Service Manual - VMH 18/28/36/48 Series Screws of right-rear panel Screws of terminal board How to remove the fan assembly. assembly 1) Remove the top cover, ② ② right front side panel and front panel from item 1. step 1~4 2) Remove the hex nut fixing the fan.
  • Page 146 Service Manual - VMH 18/28/36/48 Series 3) Remove the fan. ④ ④ 4) Unfix the hooks and remove the screws, then open the electronic control box. 5) Disconnect the fan motor ⑤ ⑤ connector CN19(3p, white) from the driver board. Remove the fan motor after unfastening four fixing screws.
  • Page 147 Service Manual - VMH 18/28/36/48 Series pieces of connection wires and ④ ④ connectors between driver board and PCB. CN55-CN7(7p, white) CN54-CN6(red) CN53-CN5(black) 6) Remove the fixing screws, then move the driver board. Disconnect the CN53 connectors and wires CN54 connected from PCB and other parts.
  • Page 148 Service Manual - VMH 18/28/36/48 Series CN10/CN44: Crankcase heating cable (black - red) CN13 CN1:L1-IN (red) CN10 CN33 CN22 CN2:L2-IN (black) CN40 CN44 CN2 CN1 Disconnect the grounding wire (yellow - green) after removing the right-rear panel. 9) Remove the PCB board. ⑧...
  • Page 149 Service Manual - VMH 18/28/36/48 Series 6) Remove the discharge pipe and suction pipe with a burner. 7) Remove the hex nuts and washers fixing the compressor to bottom plate. 8) Lift the compressor. The 4-way How to remove the 4-way valve valve Coil...
  • Page 150 Service Manual - VMH 18/28/36/48 Series  A-VMH36QU-1, A-VMH48PU-1 (WE30 metal plate) Part name Procedures Remarks How to remove the fan assembly assembly. Turn off the air ② ② conditioner. Turn off the power breaker. 2) Remove the screws of air outlet grille (8 screws) 3) Remove the hex nut fixing the fan.
  • Page 151 Service Manual - VMH 18/28/36/48 Series Screws of top 5) Remove the screws of top cover and remove the top cover. (4 screws) 6) Remove the screws of front side panel, and remove the front side panel (1 screw) ⑥ ⑥ 7) Disconnect the fan motor connectors FAN1(3p, white) and FAN2(3p, white) from DC...
  • Page 152 Service Manual - VMH 18/28/36/48 Series Panel plate How to remove the panel plate. 4) Remove big handle. (2 Screws screws) and water collector of big handle (2 screws) 5) Remove 2 screws of Screws of Water collector terminal board and 15 screws of right-rear panel and remove the right-rear Screws of...
  • Page 153 Service Manual - VMH 18/28/36/48 Series 2) Disconnect the fan motor Connector (5p, white) from the IPM board. Disconnect following 8 pieces of connection wires and connectors between IPM and other parts. CN2 (yellow) CN1 (red) CN6 (black) CN3 (yellow) U、V、W (black) CN9 (10p,white) 4) Remove the fixing screws...
  • Page 154 Service Manual - VMH 18/28/36/48 Series CN8: Discharge temperature sensor (2p, white) CN12：Heatsink temperature sensor (2p, red) CN13 CN16 CN9:T3/T4 temperature sensor CN21 (2p/2p, white) CN29 CN37 CN11:T2B-A, B, C, D, E temperature CN8 CN12 sensor (2p/2p/2p/2p/2p, white) CN9 CN11 CN15/CN23/CN26/CN30/CN33: Electronic expansion valve (6p/6p/6p/6p/6p, red)
  • Page 155 Service Manual - VMH 18/28/36/48 Series Compressor How to remove the compressor. 1) Perform work of item 1 step 5~6 and item 2. ⑤ 2) Extract refrigerant gas. 3) Remove the sound insulation material and crankcase heating cable. 4) Remove terminal cover of compressor and disconnect wires of crankcase electric heater...
  • Page 156 Service Manual - VMH 18/28/36/48 Series The 4-way How to remove the 4-way valve valve 6) Perform work of item 1 step 5~6 and item 2. Coil 7) Extract refrigerant gas. Welded parts 8) Remove the electrical parts from item 3. 9) Remove fixing screw of the coil and remove the coil.
  • Page 157 Service Manual - VMH 18/28/36/48 Series  A-VMH48PU-1 (WE30 metal plate) Part name Procedures Remarks How to remove the fan assembly assembly. 1) Turn off the air ② ② conditioner. Turn off the power breaker. 2) Remove the screws of air outlet grille (8 screws) 3) Remove the hex nut fixing 4) the fan.
  • Page 158 Service Manual - VMH 18/28/36/48 Series 7) Remove the screws of front side panel, and remove the front side panel (1 screw) ⑥ ⑥ 8) Disconnect the fan motor 9) connectors FAN1(3p, white) and FAN2(3p, white) from DC motor ⑧ ⑧ driver board.
  • Page 159 Service Manual - VMH 18/28/36/48 Series Screws of terminal board Screws of right- rear panel Screws of right- rear panel Electrical How to remove the electrical parts parts. 1) Perform work of item 1 step 5~6 and item 2. Adapter board IPM board PCB board...
  • Page 160 Service Manual - VMH 18/28/36/48 Series 3) Disconnect following 6 pieces of connection wires and connectors between IPM and other parts. CN3(red) CN2(black) U(blue), V(red), W(black) CN9(10p,white) CN8, CN5(3p) Remove the 4 screws and unfix the 4 hooks and then remove the IPM module board.
  • Page 161 Service Manual - VMH 18/28/36/48 Series CN37/CN29/CN21/CN16/CN13/CN7: S-A, S-B, S-C, S-D, S-E (3p/3p/3p/3p/3p, white) CN10: High- and low-pressure switch (2p/2p, white) Wires: ⑥ CN17/CN18: 4-way valve (blue - blue) CN19/CN20: connected to crankcase heating cable. (black - red) CN24/CN25: Electric heater of chassis (orange - orange) CN1: L-IN (red) CN3: N-IN (black)
  • Page 162 Service Manual - VMH 18/28/36/48 Series Compressor How to remove the compressor. 1) Perform work of item 1 step 5~6 and item 2. ⑤ 2) Extract refrigerant gas. 3) Remove the sound insulation material and crankcase heating cable. 4) Remove terminal cover of compressor and disconnect wires of crankcase electric heater...
  • Page 163 Service Manual - VMH 18/28/36/48 Series The 4-way How to remove the 4-way valve valve 1) Perform work of item 1 step 5~6 and item 2. Coil 2) Extract refrigerant gas. Welded parts 3) Remove the electrical parts from item 3. 4) Remove fixing screw of the coil and remove the coil.
  • Page 164 3/2021...

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Comfort-aire a-vmh18du-1Comfort-aire a-vmh28tu-1Comfort-aire a-vmh36qu-1Comfort-aire a-vmh48pu-1

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