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M‐Thermal Split Part 1 General Information 1 Unit Capacities ................... 4 2 External Appearance .................. 5 201909 3 Midea CAC Confidential...
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Table 1‐1.1: Capacity range Capacity 4kW 6kW 8kW 10kW Model V4W V6W V8W V10W (MHA‐*/D2N8) Notes: 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. 1.2 Hydronic Box Model Table 1‐1.2: Model Model SMK‐60/CGN8 SMK‐80/CGN8 Compatible OU model MHA‐V4(6)W/D2N8 MHA‐V8(10)W/D2N8 4 201909 Midea CAC Confidential...
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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. 201909 Midea CAC Confidential...
Figure 3 -7.1: Locati o n of the t emperature sensors on M -Thermal Split systems Notes: Notes: The names and functions of the temperature sensors labelled 1 to 11 in this figure are detailed in Table 3-7.1. 201909 Midea CAC Confidential...
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Port for external circulted pump/pipe pump/mix pump/2‐way valve 24 CN24 Port for SV1(3‐way valve) and SV3 25 CN28 Port for internal pump 26 CN20 Input port for transformer 27 CN1 Feedback port for temperature switch 28 CN21 Port for power supply 29 CN2 Feedback port for external temp. switch(shorted in default) 30 CN22 Control port for backup heater/booster heater 31 CN3 Control port for room thermostat(high voltage) 32 IC18 EEPROM 33 SW4 Check button 32 201909 Midea CAC Confidential...
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21 Digital display 22 Port for chassis electrical heating tape 23 Port for SV6 value 24 Port for 4‐way value 25 Port for compressor electric heating tape1 26 Port for compressor electric heating tape2 CN28 27 Output port L for invert module PCB 28 Output port L for hydro‐box control board IC23 29 EEPROM SW2 30 Check button 34 201909 Midea CAC Confidential...
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Th: Suction temperature (°C) Temperature is ≤ ‐10°C Actual value = value displayed x ‐10 Example: “1.2” indicates ‐12°C 10 TF: Radiator temperature (°C) Actual value = value displayed 11 Electric Expansive Valve Steps = value displayed × 8 12 Actual current Actual value = value displayed 13 Compressor current Actual value = value displayed 14 Voltage AC Actual value = value displayed × 10 15 Voltage DC Actual value = value displayed × 10 16 Pressure Actual value = value displayed 17 Software version Version number 18 Last fault “nn” is displayed if no error or protection events have occurred since start‐up 19 ‐‐ 36 201909 Midea CAC Confidential...
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User interface and outdoor Pd 33 temperature of condenser in cooling mode unit main PCB PP 38 Water side heat exchanger inlet temperature is User interface and hydronic Hb 50 higher than outlet temperature in heating mode box main PCB Notes: 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”. 40 201909 Midea CAC Confidential...
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M‐Thermal Split 4.2 E0, E8 Troubleshooting Digital display output Description Water flow failure. E0 indicates E8 has displayed 3 times. When an E0 error occurs, a manual system restart is required before the system can resume operation. M‐Thermal Split stops running. Error code is displayed on hydronic box main PCB and user interface. Possible causes The wire circuit is short connected or open. Water flow rate is too low. Water flow switch damaged. 42 201909 Midea CAC Confidential...
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M‐Thermal Split 4.3 E2 Troubleshooting Digital display output Description Communication error between hydronic box and user interface. M‐Thermal Split stops running. Error code is displayed on hydronic box main PCB and user interface. Possible causes 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. 44 201909 Midea CAC Confidential...
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Description E3 indicates a backup electric heater water outlet temperature sensor error. E4 indicates a domestic hot water tank temperature sensor error. H2 indicates a water side heat exchanger refrigerant outlet (gas pipe) temperature sensor error. H3 indicates a water side heat exchanger refrigerant inlet (liquid pipe) temperature sensor error. Ed indicates a water side heat exchanger water inlet temperature sensor error. HA indicates a water side heat exchanger water outlet temperature sensor error. H5 indicates a room temperature sensor error. H9 indicates a circuit 2 water outlet temperature sensor error. M‐Thermal Split stops running. Error code is displayed on hydronic box main PCB and user interface. Possible causes Temperature sensor not connected properly or has malfunctioned. Damaged hydronic box main PCB. 46 201909 Midea CAC Confidential...
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4.5 E5, E6, E9, EA Troubleshooting Digital display output Description E5 indicates an air side heat exchanger refrigerant outlet temperature sensor error. E6 indicates an outdoor ambient temperature sensor error. E9 indicates a suction pipe temperature sensor error. EA indicates a discharge temperature sensor error. M‐Thermal Split stops running. Error code is displayed on outdoor unit main PCB and user interface. Possible causes Temperature sensor not connected properly or has malfunctioned. Damaged outdoor unit main PCB. 48 201909 Midea CAC Confidential...
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Notes: Hydronic box main PCB EEPROM is designated IC18 on the main PCB for hydronic box (labeled 32 in Figure 4‐2.1 in Part4, 2.2 "Main PCB for Hydronic System"). 50 201909 Midea CAC Confidential...
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Outdoor unit main PCB damaged. Procedure HF Outdoor unit EEPROM is not connected Ensure the EEPROM is connected Yes properly properly No Replace outdoor unit main PCB Notes: Outdoor unit EEPROM is designated IC23 on the outdoor unit main PCB (labeled 29 in Figure 4‐2.2 in Part4, 2.3 "Main PCBs for Refrigerant System, Inverter Module"). 52 201909 Midea CAC Confidential...
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Yes Remove the source of interference high‐frequency transmitter or other high strength radiation device No Communication wires P Q E between main control board of outdoor unit and Yes Reconnect the communication wires hydraulic module have short circuited, disconnected or misconnected No Replace outdoor unit main PCB and hydronic box main PCB in turn Notes: Measure the voltages of transformer input port and out port. The input voltage of transformer is 220V AC, output voltage of transformer is 13.5V AC. If any voltages is abnormal, the power supply for the main control board of hydraulic module and transformer will be abnormal. Measure the voltages of transformer output port ports. If the voltages are not normal, the transformer has malfunctioned. 54 201909 Midea CAC Confidential...
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4.11 H6, HH Troubleshooting Digital display output Description H6 indicates a DC fan error. HH indicates that H6 protection has occurred 10 times in 2 hours. When HH error occurs, a manual system restart is required before the system can resume operation. The cause of HH error should be addressed promptly in order to avoid system damage. M‐Thermal Split stops running. Error code is displayed on outdoor unit main PCB and user interface. Possible causes DC fan wire is loosed. High wind speed. Fan motor blocked or has failed. Invert module damaged. Main PCB is damaged. 56 201909 Midea CAC Confidential...
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M‐Thermal Split stops running. Error code is displayed on outdoor unit main PCB and user interface. Possible causes Power supply voltage not within 90%~110% of rated voltage. Outdoor unit main PCB is damaged. Procedure H7 Power supply voltage is not within Yes Provide normal power supply 90%~110% of rated voltage No Replace outdoor unit main PCB 58 201909 Midea CAC Confidential...
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P0 indicates suction pipe low pressure protection. When the suction pressure falls below 0.14MPa, the system displays P0 protection and M‐Thermal Split stops running. When the pressure rises above 0.3MPa, P0 is removed and normal operation resumes. HP indicates P0 protection has occurred 3 times in 60 minutes. When an HP error occurs, a manual system restart is required before the system can resume operation. Error code is displayed on outdoor unit main PCB and user interface. Possible causes 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. 60 201909 Midea CAC Confidential...
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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. 201909 Midea CAC Confidential...
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Discharge pipe high pressure protection. When the discharge pressure rises above 4.2MPa, the system displays P1 protection and M‐Thermal Split stops running. When the discharge pressure falls below 3.2MPa, P1 is removed and normal operation resumes. Error code is displayed on outdoor unit main PCB and user interface. 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. 62 201909 Midea CAC Confidential...
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P3 protection and M‐Thermal Split stops running. 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. Possible causes Poor condenser heat exchange. High pressure side blockage. Inverter module damaged. Compressor damaged. Outdoor unit main PCB damaged. 64 201909 Midea CAC Confidential...
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When the compressor the discharge temperature rises above 115°C, the system displays P4 protection and M‐Thermal Split stops running. When the discharge temperature falls below 90°C, P4 is removed and normal operation resumes. Error code is displayed on refrigerant system main PCB and user interface. Possible causes Temperature sensor error High pressure side blockage. Poor condenser heat exchange. Outdoor unit main PCB damaged. 66 201909 Midea CAC Confidential...
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High pressure switch connection is port CN13 on the main PCB (labeled 10 in Figure 4‐2.2 in Part4, 2.3 "Main PCBs for Refrigerant System, Inverter Module"). Pressure sensor connectin is port CN4 on the main control board (labeled 15 in Figure 4‐2.2 in Part4, 2.3 "Main PCBs for Refrigerant System, Inverter Module") Measure the resistance among the three terminals of the pressure sensor. If the resistance is of the order of mega Ohms or infinite, the pressure sensor has failed. 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. 68 201909 Midea CAC Confidential...
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Characteristics”. Refer to the M‐Thermal Split Engineering Data Book, Part 5, 15 “SPECIAL FUNCTIONS”. 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 “Hydronic Box Layout”. 70 201909 Midea CAC Confidential...
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310V DC. When the fan motor is running, the voltage between P and N terminal on inverter module is 380V DC. L0/L4 troubleshooting Situation 1: L0 or L4 error appears immediately after the outdoor unit is powered‐on L0 / L4 Yes Inverter module is damaged Replace the inverter module Notes: Measure the resistance between each of U, V and W and each of P and N on the inverter module. All the resistances should be infinite. If any of them are not infinite, the inverter module is damaged and should be replaced. Refer to Figure 4‐2.3 or 4‐2.5 in Part 4, 2.1 “Outdoor Unit PCBs”. 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 4‐4.1. 72 201909 Midea CAC Confidential...
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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 is failed. 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 4‐4.1. Situation 4: L0 error appears occasionally/irregularly L0 Yes The outdoor unit ventilation is not good Ensure enough space for unit ventilation 74 201909 Midea CAC Confidential...
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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 “Hydronic Box Layout” and to Table 4-5.3 in Part 4, 5.1 “Temperature Sensor Resistance Characteristics”. 201909 Midea CAC Confidential...
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62°C for more than 3 seconds, the system displays Pd protection and M‐Thermal Split stops running. When the air side heat exchanger refrigerant outlet temperature returns drops below 52°C, Pd is removed and normal operation resumes. M‐Thermal Split stops running. Error code is displayed on outdoor unit main PCB and user interface. Possible causes Temperature sensor not connected properly or has malfunctioned. Poor condenser heat exchange. Fan motor damaged. Hydronic box main PCB damaged. 78 201909 Midea CAC Confidential...
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M‐Thermal Split 4.22 PP Troubleshooting Digital display output Description Water side heat exchanger inlet temperature is higher than outlet temperature in heating mode. M‐Thermal Split stops running. Error code is displayed on hydronic box main PCB and user interface. Hb indicates PP has displayed 3 times. Possible causes Temperature sensor not connected properly or has malfunctioned. 4‐way valve is blocked or damaged. Hydronic box main PCB damaged. 80 201909 Midea CAC Confidential...
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Ver. 2019‐09 Commercial Air Conditioner Division Midea Group Add.: Midea Headquarters Building, 6 Midea Avenue, Shunde, Foshan, Guangdong, China Postal code: 528311 Tel: +86‐757‐26338346; Fax: +86‐757‐22390205 cac.midea.com / global.midea.com Note: Product specifications change from time to time as product improvements and developments are released and may vary from those in this document. Midea CAC Confidential...