Midea M-Thermal A Series Service Manual
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Midea M-Thermal A Series Service Manual

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Commercial Air Conditioners
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M-Thermal A Series Split
Midea CAC Confidential

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Summary of Contents for Midea M-Thermal A Series

  • Page 1 Commercial Air Conditioners Service Manual M-Thermal A Series Split Midea CAC Confidential...
  • Page 2 M thermal Split CONTENTS Part 1 General Information ................3 Part 2 Component Layout and Refrigerant Circuits ........7 Part 3 Control ....................17 Part 4 Diagnosis and Troubleshooting ............31 202004 Midea CAC Confidential...
  • Page 3 M thermal Split 202004 Midea CAC Confidential...

  • Page 4: Part 1 General Information

    M thermal Split Part 1 General Information 1 Unit Capacities ................... 4 2 External Appearance .................. 5 202004 Midea CAC Confidential...
  • Page 5 The full model names can be obtained by substituting the asterisk in the model name format given in the left-hand column of the table above with the shortened model names given in the table. For example, the model name for the 10kW model is MHA-V10W/D2N8-B. 1.2 Hydronic Box Model Table 1-1.2: Model Model HB-A60/CGN8-B HB-A100/CGN8-B HB-A160/CGN8-B MHA-V12(14,16)W/D2N8-B Compatible OU model MHA-V4(6)W/D2N8-B MHA-V8(10)W/D2N8-B MHA-V12(14,16)W/D2RN8-B 202004 Midea CAC Confidential...
  • Page 6 M thermal Split 2 External Appearance 2.1 Outdoor Unit Appearance Table 1-2.1: Outdoor unit appearance MHA-V8(10,12,14,16)W/D2N8 MHA-V4(6)W/D2N8-B MHA-V12(14,16)W/D2RN8 2.2 Hydronic Box Appearance Table 1-2.2: Hydronic box appearance HB-A60/CGN8-B HB-A100/CGN8-B HB-A160/CGN8-B 202004 Midea CAC Confidential...
  • Page 7 M thermal Split 202004 Midea CAC Confidential...

  • Page 8: Part 2 Component Layout And Refrigerant Circuits

    M thermal Split Part 2 Component Layout and Refrigerant Circuits Layout of Functional Components ............8 Piping Diagrams .................. 13 Refrigerant Flow Diagrams ..............15 202004 Midea CAC Confidential...
  • Page 9 M thermal Split 1 Layout of Functional Components 1.1 Outdoor Unit Layout MHA-V4W/D2N8-B / MHA-V6W/D2N8-B Figure 2-1.1: MHA-V4(6)W/D2N8-B top view Figure 2-1.2: MHA-V4(6)W/D2N8-B front view 202004 Midea CAC Confidential...
  • Page 10 M thermal Split MHA-V8W/D2N8-B / MHA-V10W/D2N8-B Figure 2-1.3: MHA-V8(10)W/D2N8-B top view Figure 2-1.4: MHA-V8(10)W/D2N8-B front view 202004 Midea CAC Confidential...
  • Page 11 M thermal Split MHA-V12W/D2N8-B / MHA-V14W/D2N8-B / MHA-V16W/D2N8-B Figure 2-1.5: MHA-V12(14,16)W/D2N8-B top view Figure 2-1.6: MHA-V12(14,16)W/D2N8-B front view 202004 Midea CAC Confidential...
  • Page 12 M thermal Split MHA-V12W/D2RN8-B / MHA-V14W/D2RN8-B / MHA-V16W/D2RN8-B Figure 2-1.7: MHA-V12(14,16)W/D2RN8-B top view Figure 2-1.8: MHA-V12(14,16)W/D2RN8-B front view 202004 Midea CAC Confidential...
  • Page 13 M thermal Split 1.2 Hydronic Box Layout Figure 2-1.9: HB-A60(100,160)/CGN8-B oblique view Air purge valve Water flow switch Water side heat exchanger Electric control box Expansion vessel Water pump Manometer Safety valve 202004 Midea CAC Confidential...
  • Page 14 Regulate refrigerant system pressure. When refrigerant system pressure rises above the upper limit or falls below the lower limit, the high or low pressure switches turn off, stopping the compressor. 4. Separator: Separates liquid refrigerant from gas refrigerant to protect compressor from liquid hammering. 202004 Midea CAC Confidential...
  • Page 15 Provides additional heating capacity when the heating capacity of the heat pump is insufficient due to very low outdoor temperature. Also protects the external water piping from freezing. 6. Manometer: Provides water circuit pressure readout. 7. Water pump: Circulates water in the water circuit. 202004 Midea CAC Confidential...
  • Page 16 High temperature, high pressure liquid Low temperature, low pressure Hydronic box Pressure sensor Stop valve 4-way Air side heat exchanger Low pressure valve switch Stop valve Filter High pressure Electronic expansion valve switch Filter Electronic expansion valve capacity 202004 Midea CAC Confidential...
  • Page 17 M thermal Split 202004 Midea CAC Confidential...

  • Page 18: Table Of Contents

    2 Standby Control ..................18 3 Startup Control ..................19 4 Normal Operation Control ............... 22 5 Protection Control ................... 23 6 Special Control ..................26 7 Role of Temperature Sensors in Control Functions ........29 202004 Midea CAC Confidential...

  • Page 19: Stop Operation

    (either manually or when the power has returned following a power outage), the crankcase heater turns on. 2.2 Water Pump Control When the outdoor unit is in standby, the internal and external circulator pumps run continuously. 202004 Midea CAC Confidential...

  • Page 20: Startup Control

    36rps 32rps Time (s) Notes: Once the first, 40-second stage of the program is complete, the program proceeds to the subsequent stages in a step-by-step fashion and exits when the target rotation speed has been reached. 202004 Midea CAC Confidential...
  • Page 21 42rps 32rps Time (s) Notes: Once the first, 40-second stage of the program is complete, the program proceeds to the subsequent stages in a step-by-step fashion and exits when the target rotation speed has been reached. 202004 Midea CAC Confidential...
  • Page 22 Electronic expansion valve controlled according to outdoor ambient temperature, discharge temperature, suction superheat Four-way valve 4-WAY Notes: Refer to Part 3, 3.2 Compressor Startup Program . Refer to Table 3-4.3 in Part 3, 4.6 Outdoor Fan Control . 202004 Midea CAC Confidential...

  • Page 23: Normal Operation Control

    EXV is then controlled according to suction superheat, discharge temperature and compressor speed. When the outdoor unit is in standby: The EXV is at standby position. When the outdoor unit stops: The EXV first closes fully, then moves to the standby position. 202004 Midea CAC Confidential...

  • Page 24: Protection Control

    This control protects the refrigerant system from abnormally low pressure and protects the compressor from transient drops in pressure. Figure 3-5.2: Low pressure protection control Normal operation < 0.14MPa > 0.30MPa Low pressure protection, error code P0 is displayed Notes: : Suction pressure 202004 Midea CAC Confidential...
  • Page 25 Model name MHA-V4(6)W/D2N8-B MHA-V8(10)W/D2N8-B MHA-V12(14,16)W/D2N8-B MHA-V12(14,16)W/D2RN8-B Current When the compressor current rises above Current the system displays P3 protection and the unit stops running. When the compressor current drops below Current , the compressor enters re-start control. 202004 Midea CAC Confidential...
  • Page 26 In heating/DHW mode, leaving water temperature is below 2°C, the anti-freeze protection actions. When water side heat exchanger anti-freeze protection occurs the system displays error code Pb and the unit stops running. 202004 Midea CAC Confidential...

  • Page 27: Special Control

    The force cool mode can be ended by pushing the button on the outdoor refrigerant system main PCB FORCE 5s or this mode will be ended automatic if the system has operated force cool mode for more than 30 minutes. 202004 Midea CAC Confidential...
  • Page 28 With the help of hydraulic adapter PCB, totally 8 thermostats can be used at the same time for maximum 8 rooms to control heat pump. Note: M thermal units just have the controlling function, while the mixing valve, water pump of each zone need to be field supplied and connect to M thermal unit. 202004 Midea CAC Confidential...
  • Page 29 TBH is only controlled by M1M2. If dry contract closes, T5<65 then TBH opens until water tank temperature reaches 70 . For AHS control In heating mode AHS on/off is only controlled by M1M2. In DHW mode, M1M2 control does not affect AHS on/off. 202004 Midea CAC Confidential...

  • Page 30: Role Of Temperature Sensors In Control Functions

    7 Role of Temperature Sensors in Control Functions Figure 3-7.1: Location of the temperature sensors on M thermal Split systems Notes: The names and functions of the temperature sensors labelled 1 to 11 in this figure are detailed in Table 3-7.1. 202004 Midea CAC Confidential...
  • Page 31 Water side heat exchanger water outlet temperature sensor Tw_out Water side heat exchanger water inlet temperature sensor Tw_in Final water outlet temperature sensor Domestic hot water tank temperature sensor Room temperature sensor (built in wired controller) 202004 Midea CAC Confidential...

  • Page 32: Part 4 Diagnosis And Troubleshooting

    M thermal Split Part 4 Diagnosis and Troubleshooting 1 Electric Control Box Layout ............... 32 2 PCBs ......................35 3 Error Code Table ..................49 4 Troubleshooting ..................51 5 Appendix to Part 4 ................. 107 202004 Midea CAC Confidential...

  • Page 33: Electric Control Box Layout

    1 Electric Control Box Layout 1.1 Outdoor Unit Electric Control Box Layout Figure 4-1.1: MHA-V4(6)W/D2N8-B electric control box Main PCB Inverter module Figure 4-1.2: MHA-V8(10)W/D2N8-B electric control box Main PCB Inverter module Figure 4-1.3: MHA-V12(14,16)W/D2N8-B electric control box 202004 Midea CAC Confidential...
  • Page 34 M thermal Split Main PCB Inverter module Figure 4-1.4: MHA-V12(14,16)W/D2RN8-B electric control box Main PCB Inverter module Main Power Electric Reactor Filter board DCFAN Electric Reactor 202004 Midea CAC Confidential...
  • Page 35 M thermal Split 1.2 Hydronic Box Electric Control Box Layout Figure 4-1.5: HB-A60(100,160)/CGN8-B Main control board 202004 Midea CAC Confidential...

  • Page 36: Pcbs

    Outdoor Unit Electric Control Box Layout . The locations of each PCB in the hydronic box electric control box are shown in Figures 4-1.5 in Part 4, 1.2 Hydronic Box Electric Control Box Layout . 2.2 Main PCB for Hydronic System Figure 4-2.1: HB-A60(100,160)/CGN8-B hydronic box main PCB 202004 Midea CAC Confidential...
  • Page 37 Feedback port for temperature switch(shorted in default) CN22 Control port for backup heater1/booster heater/Reserved CN41 Port for anti-freeze electric heating tape CN42 Port for anti-freeze electric heating tape CN29 Port for anti-freeze electric heating tape IC39 EEPROM 202004 Midea CAC Confidential...
  • Page 38 M thermal Split 2.3 Main PCBs for Refrigerant System, Inverter Module Figure 4-2.2: MHA-V4(6,8,10)W/D2N8-B outdoor unit main PCB for refrigerant system 27 26 25 24 22 21 20 202004 Midea CAC Confidential...
  • Page 39 CN33 Port for electrical expansion value CN16 Port for chassis electrical heating tape(Optional) Port for 4-way value Port for SV6 value Port for compressor electric heating tape 1 CN18 Port for compressor electric heating tape 2 202004 Midea CAC Confidential...
  • Page 40 M thermal Split Figure 4-2.3 MHA-V12(14,16)W/D2N8-B outdoor unit main PCB for refrigerant system 27 26 25 24 22 21 20 202004 Midea CAC Confidential...
  • Page 41 CN33 Port for electrical expansion value CN16 Port for chassis electrical heating tape(Optional) Port for 4-way value Port for SV6 value Port for compressor electric heating tape 1 CN18 Port for compressor electric heating tape 2 202004 Midea CAC Confidential...
  • Page 42 M thermal Split Figure 4-2.4 MHA-V12(14,16)W/D2RN8-B outdoor unit main PCB for refrigerant system 26 25 24 23 22 21 20 19 18 17 16 15 14 202004 Midea CAC Confidential...
  • Page 43 Key for fore cool & check S3, S4 Port for communication H1H2E CN37 Port for electrical expansion value CN22 Port for fan 15VDC power supply CN30 Port for fan 310VDC power supply CN53 Port for fan CN109 202004 Midea CAC Confidential...
  • Page 44 M thermal Split Figure 4-2.5 MHA-V4(6,8,10)W/D2N8-B outdoor unit inverter module For 4/6kW model For 8/10kW model 202004 Midea CAC Confidential...
  • Page 45 Compressor connection port W Output port for +12V/9V CN20 Port for fan CN19 Port for communication with main PCB for filter board CN32 Input port N for rectifier bridge CN502 Input port L for rectifier bridge CN501 EEPROM IC320 202004 Midea CAC Confidential...
  • Page 46 Output port for +12V/9V CN20 Port for communication with main PCB for filter board CN32 Port for high pressure switch CN23 Reserved Input port L for rectifier bridge CN501 Input port N for rectifier bridge CN502 EEPROM IC14 202004 Midea CAC Confidential...
  • Page 47 Power Input port L1 CN16 Input port P_in for IPM module Port for communication with main PCB for filter board PED board CN22 Power for high pressure switch CN23 Port for communication with PCB EEPROM IC25 202004 Midea CAC Confidential...
  • Page 48 Power supply port for Inverter module CN214 Ground wire Port for communication with main PCB for filter board Power supply port for main control board CN30 Port for ground wire Port for ground wire Power supply L1 202004 Midea CAC Confidential...
  • Page 49 2, pos=5 is address 5. Figure 4-2.10: Rotating switch Figure 4-2.11: Connection Note: Wired controller is integrated in the hydronic box. Figure 4-2.12: Wiring Input Voltage(A/B) 13.5VAC Wiring size 0.75mm² 202004 Midea CAC Confidential...

  • Page 50: Error Code Table

    PP protection appears three times in a row and Twout<7 Invert module EEPROM error DC fan error(H6 appears 10 times in 120min) Low pressure protection for cooling mode Low pressure switch protection High pressure switch protection Compressor current protection Discharge temperature protection 202004 Midea CAC Confidential...
  • Page 51 When the error code appears, the error code corresponding to the serial number can be obtained through the H1H2 port by using the host computer to query the wired controller register. Sensor names in this service manual referring to refrigerant flow is named according refrigerant flow during cooling operation refer to Part 2, 3 Refrigerant Flow Diagrams . 202004 Midea CAC Confidential...

  • Page 52: Troubleshooting

    Power-off the outdoor units before connecting or disconnecting any connections or wiring, otherwise electric shock (which can cause physical injury or death) may occur or damage to components may occur. 202004 Midea CAC Confidential...
  • Page 53 M thermal Split stops running. Error code is displayed on hydronic box main PCB and user interface. 4.2.3 Possible causes The wire circuit is short connected or open. Water flow rate is too low. Water flow switch damaged. 202004 Midea CAC Confidential...
  • Page 54 Water flow switch connection is port CN8 on the main PCB for hydronic box (labeled 9 in Figure 4-2.1 in Part4, 2.2 "Main PCB for Hydronic System"). Check water pressure on the manometer. If the water pressure is not > 1 bar, water flow is insufficient. Refer to Figure 2-1.9 in Part 2, 1 Hydronic Box Layout . 202004 Midea CAC Confidential...
  • Page 55 M thermal Split stops running. Error code is displayed on outdoor unit main PCB and user interface. 4.3.3 Possible causes Power supply phases not connected in correct sequence. Power supply terminals loose. Power supply abnormal. Main PCB damaged. 202004 Midea CAC Confidential...
  • Page 56 Therefore if multiple units are to be used, the phase sequence should be staggered, so that the current is distributed among the three phases equally. Loose power supply terminals can cause the compressors to operate abnormally and compressor current to be very large. 202004 Midea CAC Confidential...
  • Page 57 Communication wires between hydronic box and user interface not connected properly. Communication wiring X Y E terminals misconnected. Loosened wiring within electric control box. Interference from high voltage wires or other sources of electromagnetic radiation. Damaged main PCB or electric control box communication terminals block. 202004 Midea CAC Confidential...
  • Page 58 Replace hydronic box main PCB Notes: Measure the resistance among X, Y Y and E is infinite. Communication wiring has polarity. Ensure that the X wire is connected to X terminals and the Y wire is connected to Y terminals. 202004 Midea CAC Confidential...
  • Page 59 M thermal Split stops running. Error code is displayed on hydronic box main PCB and user interface. 4.5.3 Possible causes Temperature sensor not connected properly or has malfunctioned. Damaged hydronic box main PCB. 202004 Midea CAC Confidential...
  • Page 60 Measure sensor resistance. If the resistance is too low, the sensor has short-circuited. If the resistance is not consistent with the sensor s resistance characteristics table, the sensor has failed. Refer to Table 4-5.1 or 4-5.3 in Part 4, 5.1 202004 Midea CAC Confidential...
  • Page 61 EA indicates a discharge temperature sensor error. M thermal Split stops running. Error code is displayed on outdoor unit main PCB and user interface. 4.6.3 Possible causes Temperature sensor not connected properly or has malfunctioned. Damaged outdoor unit main PCB. 202004 Midea CAC Confidential...
  • Page 62 Measure sensor resistance. If the resistance is too low, the sensor has short-circuited. If the resistance is not consistent with the sensor s resistance characteristics table, the sensor has failed. Refer to Table 4-5.1, and Table 4-5.2 in Part 4, 5.1 202004 Midea CAC Confidential...
  • Page 63 Replace hydronic box main PCB Notes: Hydronic box main PCB EEPROM is designated IC39 on the main PCB for hydronic box (labeled 31 in Figure 4-2.1 in Part4, 2.2 "Main PCB for Hydronic System"). 202004 Midea CAC Confidential...
  • Page 64 LED on the Inverter Voltage of PN is 380V. Check the main board. Modules is lighting The input power of The main board is inverter module is damaged, change it. abnormal The invert module is damaged, change it. 202004 Midea CAC Confidential...
  • Page 65 (labeled 11 in Figure 4-2.6 in Part4, 2.3 "Main PCBs for Refrigerant System, Inverter Module"), designated IC25 on the MHA-V12(14,16)W/D2RN8-B invert module outdoor unit (labeled 14 in Figure 4-2.7 in Part4, 2.3 "Main PCBs for Refrigerant System, Inverter Module"). 202004 Midea CAC Confidential...
  • Page 66 Error code is displayed on hydronic box main PCB, outdoor unit main PCB and user interface. 4.10.3 Possible causes Power supply abnormal. Transformer malfunction. Interference from a source of electromagnetic radiation. Outdoor unit main PCB or hydronic box main PCB damaged. 202004 Midea CAC Confidential...
  • Page 67 Measure the voltages of transformer output port ports. If the voltages are not normal, the transformer has malfunctioned. 202004 Midea CAC Confidential...
  • Page 68 There is a source of electromagnetic radiation near the unit, such as Remove the source of interference high-frequency transmitter or other high strength radiation device Replace outdoor unit main PCB and inverter driven module in turn 202004 Midea CAC Confidential...
  • Page 69 Error code is displayed on outdoor unit main PCB and user interface. 4.12.3 Possible causes DC fan wire is loosed. High wind speed. Fan motor blocked or has failed. Invert module damaged. Main PCB is damaged. 202004 Midea CAC Confidential...
  • Page 70 MHA-V12(14,16)W/D2N8-B outdoor unit inverter module PCB (labeled 4 in Figure 4-2.6 in Part 4, 2. 3 "Main PCB for Refrigerant System, Inverter Module"), port CN109 on the MHA-V12(14,16)W/D2RN8-B outdoor unit refrigerant system main PCB (labeled 30 in Figure 4-2.4 in Part 4, 2. 3 "Main PCB for Refrigerant System, Inverter Module"). 202004 Midea CAC Confidential...
  • Page 71 Power supply voltage not within 90%~110% of rated voltage. Outdoor unit main PCB is damaged. 4.13.4 Procedure Power supply voltage is not within Provide normal power supply 90%~110% of rated voltage Replace outdoor unit main PCB 202004 Midea CAC Confidential...
  • Page 72 PCB (labeled 19 in Figure 4-2.3 in Part 4, 2. 3 "Main PCB for Refrigerant System, Inverter Module"), port CN6 on the MHA-V12(14,16)W/D2RN8-B outdoor unit refrigerant system main PCB (labeled 13 in Figure 4-2.4 in Part 4, 2. 3 "Main PCB for Refrigerant System, Inverter Module"). 202004 Midea CAC Confidential...
  • Page 73 Low pressure switch not connected properly or has malfunctioned. Insufficient refrigerant. Low pressure side blockage. Poor evaporator heat exchange in heating mode or DHW mode. Insufficient water flow in cooling mode. Outdoor unit main PCB damaged. 202004 Midea CAC Confidential...
  • Page 74 For normal system parameters. Check air side heat exchanger, fan and air outlets for dirt/blockages. Check water side heat exchanger, water piping, circulator pumps and water flow switch for dirt/blockages. 202004 Midea CAC Confidential...
  • Page 75 Error code is displayed on outdoor unit main PCB and user interface. 4.16.3 Possible causes Pressure sensor/switch not connected properly or has malfunctioned. Excess refrigerant. System contains air or nitrogen. High pressure side blockage. Poor condenser heat exchange. Outdoor unit main PCB damaged. 202004 Midea CAC Confidential...
  • Page 76 Check water pressure on the manometer. If the water pressure is not > 1 bar, water flow is insufficient. Refer to Figure 2-1.9 in Part 2, 1.2 Hydronic Box 202004 Midea CAC Confidential...
  • Page 77 When the current returns to the normal range, P3 is removed and normal operation resumes. Error code is displayed on refrigerant system main PCB and user interface. 4.17.3 Possible causes Poor condenser heat exchange. High pressure side blockage. Inverter module damaged. Compressor damaged. Outdoor unit main PCB damaged. 202004 Midea CAC Confidential...
  • Page 78 The normal resistances of the inverter compressor are 0.7- among U V W and infinite between each of U V W and ground. If any of the resistances differ from these specifications, the compressor has malfunctioned. 202004 Midea CAC Confidential...
  • Page 79 Split stops running. When the discharge temperature falls below 95°C, P4 is removed and normal operation resumes. Error code is displayed on refrigerant system main PCB and user interface. 4.18.3 Possible causes Temperature sensor error High pressure side blockage. Poor condenser heat exchange. Outdoor unit main PCB damaged. 202004 Midea CAC Confidential...
  • Page 80 Discharge pipe temperature sensor connection is port CN8 on the MHA-V4(6,8,10)W/D2N8-B outdoor unit refrigerant system main PCB (labeled 15 in Figure 4-2.2 in Part4, 2.3 "Main PCB for Refrigerant System, Inverter Module"). port CN8 on the MHA-V12(14,16)W/D2N8-B outdoor unit refrigerant 202004 Midea CAC Confidential...
  • Page 81 High pressure side blockage causes discharge temperature to be higher than normal, discharge pressure to be higher than normal and suction pressure to be lower than normal. Check air side heat exchanger, fan and air outlets for dirt/blockages. Check the water side heat exchanger, water piping, circulator pumps and water flow switch for dirt/blockages. 202004 Midea CAC Confidential...
  • Page 82 M thermal Split stops running. Error code is displayed on hydronic box main PCB and user interface. 4.19.3 Possible causes Temperature sensor not connected properly or has malfunctioned. Water piping contains air. Insufficient water flow. Hydronic box main PCB damaged. 202004 Midea CAC Confidential...
  • Page 83 Refer to the M thermal Split Engineering Data Book, Part 5, 1 Check water pressure on the manometer. If the water pressure is not > 1 bar, water flow is insufficient. Refer to Figures 2-1.7 and 2-1.8 in Part 2, 1.2 202004 Midea CAC Confidential...
  • Page 84 MCE error(DC bus low or high voltage protection or software over current protection) Zero speed protection Compressor frequency variation greater than 15Hz within 1 second protection Actual compressor frequency differs from target frequency by more than 15Hz protection 202004 Midea CAC Confidential...
  • Page 85 L9 - Actual compressor frequency differs from target frequency by more than 15Hz Flashes 17 times and stops for 1 second, then repeats protection Figure 4-4.1: LED location of inverter module Inverter Module(4-10KW): LED301/302/303 Inverter Module(12-16KW): LED1/LED2/LED3 202004 Midea CAC Confidential...
  • Page 86 When replacing an inverter module, a layer of thermally conductive silica gel should be painted on the IPM module, IGBT, diode, brigde rectifier (on the reverse side of the inverter module). Refer to Figure 4-4.2. Figure 4-4.2: Replacing an inverter module IGBT diode IGBT diode brigde rectifier 202004 Midea CAC Confidential...
  • Page 87 When replacing an inverter module, a layer of thermally conductive silica gel should be painted on the IPM module, IGBT, diode brigde rectifer (on the reverse side of the inverter module PCB). Refer to Figure 4-4.2. The normal resistances of the inverter compressor are 0.7- differ from these specifications, the compressor has malfunctioned. 202004 Midea CAC Confidential...
  • Page 88 When replacing an inverter module, a layer of thermally conductive silica gel should be painted on the PFC and IPM modules (on the reverse side of the inverter module PCB). Refer to Figure 4-4.2. Situation 4: L0 error appears occasionally/irregularly The outdoor unit ventilation is not good Ensure enough space for unit ventilation 202004 Midea CAC Confidential...
  • Page 89 Situation 2: L1 or L2 error appears after the compressor has been running for a period of time and the compressor speed is over 20rps L1 /L2 Relay on outdoor unit main PCB is open Replace the outdoor unit main PCB Replace the inverter module 202004 Midea CAC Confidential...
  • Page 90 Replace inverter module PCB Replace the compressor When replacing an inverter module, a layer of thermally conductive silica gel should be painted on IPM module (on the reverse side of the inverter module PCB). Refer to Figure 4-4.2. 202004 Midea CAC Confidential...
  • Page 91 MCE error(DC bus low or high voltage protection or software over current protection) Zero speed protection Compressor frequency variation greater than 15Hz within one second protection Actual compressor frequency differs from target frequency by more than 15Hz protection 202004 Midea CAC Confidential...
  • Page 92 380-415V AC power supply change to DC power supply after bridge rectifier. Contactor is open the current across the PTC to charge capacitor, after 5 seconds the contactor closed. The capacitor output steady 540V DC power supply for inverter module P N terminals. 202004 Midea CAC Confidential...
  • Page 93 When replacing an inverter module, a layer of thermally conductive silica gel should be painted on the IPM module (on the reverse side of the inverter module PCB). Refer to Figure 4-4.2. Figure 4-4.6: F0 and GND voltage on IC28-1 F0 IC28-4 GND Vnormal = 5V IC28-1 F0 IC28-4 GND 202004 Midea CAC Confidential...
  • Page 94 N terminal of capacitor. Refer to Figure 4-4.7. Figure 4-4.7: DC bus wire connection L1L2L3,PIN- POUT L1 L2 L3 Pin Pout The normal resistances of the inverter compressor are 0.7- differ from these specifications, the compressor has malfunctioned. 202004 Midea CAC Confidential...
  • Page 95 Figure 4-4.8: Connection port for inverter module When replacing an inverter module, a layer of thermally conductive silica gel should be painted on the IPM module (on the reverse side of the inverter module PCB). Refer to Figure 4-4.2. 202004 Midea CAC Confidential...
  • Page 96 Use clip-on ammeter to measure the compressor current, if the current is normal indicates the inverter module is failed, if the current is abnormal indicates the compressor has failed. Situation 5: L0 error appears occasionally/irregularly The outdoor unit ventilation is not good Ensure enough space for unit ventilation 202004 Midea CAC Confidential...
  • Page 97 DC voltage between terminal P and N is Check power supply, three phase bridge abnormal rectifier Replace the main PCB Notes: P N +15V terminal on refrigerant system main PCB. Refer to Figure4-4.9. Voltage between N and +15. Refer to Figure4-4.10 202004 Midea CAC Confidential...
  • Page 98 (terminals 1, 2 and 3) in turn. The voltage between terminal 4 and each of terminals 1, 2 and 3 should be infinite. If the voltage is 0, the bridge rectifier has failed. Figure 4-4.11: Bridge rectifier Three phase AC power input DC power output Schematic diagram 202004 Midea CAC Confidential...
  • Page 99 Re-start the unit, use clip-on ammeter to measure the compressor current, if the current is normal indicates the compressor is failed, if the current is abnormal indicates the inverter PCB is failed.. 4.21.9 L5/L8/L9 troubleshooting L5/L8/L9 The wire is not connected properly Ensure wire is connected properly Inverter module PCB has malfunctioned Replace inverter module PCB Replace the compressor 202004 Midea CAC Confidential...
  • Page 100 M-Thermal Split stops running. Error code is displayed on outdoor unit main PCB and user interface. 4.22.3 Possible causes Temperature sensor not connected properly or has malfunctioned. Poor condenser heat exchange. Fan motor damaged. Hydronic box main PCB damaged. 202004 Midea CAC Confidential...
  • Page 101 Refer to Part 2, 1.1 and to Table 4-5.1 in Part 4, 5.1 Check air side heat exchanger, fan and air outlets for dirt/blockages. High pressure switch connection is port CN13 on the 202004 Midea CAC Confidential...
  • Page 102 Error code is displayed on hydronic box main PCB and user interface. Hb indicates PP has displayed 3 times. 4.23.3 Possible causes Temperature sensor not connected properly or has malfunctioned. 4-way valve is blocked or damaged. Hydronic box main PCB damaged. 202004 Midea CAC Confidential...
  • Page 103 Refer to Part 2, 1.2 Hydronic Box Layout and to Table 4-5.3 in Part 4, 5.1 Restart the unit in cooling mode to change the refrigerant flow direction. If the unit does not operate normally, the 4-way valve is blocked or damaged. 202004 Midea CAC Confidential...
  • Page 104 The space between the units is too narrow for heat exchanger. Heat exchanger is dirty or something is block on the surface. Fan is not running. Water flow rate is low. Water outlet temp. sensor is loosen or broken. 202004 Midea CAC Confidential...
  • Page 105 Measure sensor resistance. If the resistance is too low, the sensor has short-circuited. If the resistance is not consistent with the sensor s resistance characteristics table, the sensor has failed. Refer to Part 2, 1.2 and to Table 4-5.3 in Part 4, 5.1 202004 Midea CAC Confidential...
  • Page 106 Digital display output 4.25.2 Description PED PCB failure M thermal Split stops running. Error code is displayed on hydronic box main PCB and user interface. 4.25.3 Possible causes Power supply problem. PED board broken. IPM module broken. 202004 Midea CAC Confidential...
  • Page 107 Replace PED PCB and power on again. IPM module broken. Replace IPM module and power on again. Notes: PED is port CN22 on the hydronic box main PCB (labeled 11 in Figure 4-2.7: MHA-V12(14,16)W/D2RN8-B outdoor unit inverter module ). 202004 Midea CAC Confidential...

  • Page 108: Appendix To Part 4

    Measure sensor resistance. If the resistance is too low, the sensor has short-circuited. If the resistance is not consistent with the sensor s resistance characteristics table, the sensor has failed. Refer to Part 2, 1.2 and to Table 4-5.3 in Part 4, 5.1 5 Appendix to Part 4 202004 Midea CAC Confidential...
  • Page 109 25.268 4.046 0.942 24.003 3.887 0.912 22.808 3.735 0.883 21.678 3.59 0.855 20.61 3.451 0.828 19.601 3.318 0.802 18.646 3.191 0.777 17.743 3.069 0.753 16.888 2.952 0.73 Table 4-5.2: Compressor discharge pipe temperature sensor resistance characteristics 202004 Midea CAC Confidential...
  • Page 110 Table 4-5.3: Water side heat exchanger water inlet / outlet temperature sensor, final outlet water temperature sensor and DHW temperature sensor resistance characteristics Temperature Temperature Temperature Temperature Resistance Resistance Resistance Resistance (k ) (k ) (k ) (k ) (°C) (°C) (°C) (°C) 202004 Midea CAC Confidential...
  • Page 111 178.22 28.269 6.5228 168.31 27.139 6.3114 160.90 26.061 6.1078 152.96 25.031 5.9117 145.45 24.048 5.7228 138.35 23.109 5.5409 131.64 22.212 5.3655 125.28 21.355 5.1965 119.27 20.536 5.0336 113.58 19.752 4.8765 108.18 19.003 4.7251 103.07 18.286 4.5790 202004 Midea CAC Confidential...
  • Page 112 Note: Product specifications change from time to time as product improvements and developments are released and may vary from those in this document. GD MIDEA Heating & Ventilating Equipment Co. Ltd participates in the ECP programme for LCP-HP. Check ongoing validity of certificate: www. eurovent-certification.com...

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Hb-a60/cgn8-bHb-a100/cgn8-bHb-a160/cgn8-bMha-v4w/d2n8-bMha-v6w/d2n8-bMha-v8w/d2n8 ... Show all

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