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MDV ATOM -V12W/DHN1 Service Manual

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Service
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Model:
Series
MDV-V12W/DHN1(At)
MDV-V18W/DHN1(At)
MDV-V21W/DHN1(At)
MDV-V28W/DHN1(At)
MDV-V36W/DHN1A(At)
Commercial Air Condi�oners
MDV-V42W/DHN1A(At)
MDV-V48W/DHN1(At)
MDV-V56W/DHN1(At)
MDV-V60W/DHN1(At)
R410A

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Summary of Contents for MDV ATOM MDV-V12W/DHN1

  • Page 1 R410A Commercial Air Condi�oners Service Manual Series Model: MDV-V12W/DHN1(At) MDV-V42W/DHN1A(At) MDV-V18W/DHN1(At) MDV-V48W/DHN1(At) MDV-V56W/DHN1(At) MDV-V21W/DHN1(At) MDV-V60W/DHN1(At) MDV-V28W/DHN1(At) MDV-V36W/DHN1A(At)

  • Page 2: Table Of Contents

    Atom B Series VRF 50/60Hz CONTENTS Part 1 General Informa�on Part 2 Component Layout and Refrigerant Circuits Part 3 Control Part 4 Field Settings Part 5 Electrical Components and Wiring Diagrams 32 Part 6 Diagnosis and Troubleshoo�ng...
  • Page 3 Atom B Series VRF 50/60Hz...

  • Page 4: Part 1 General Informa�On

    Atom Series VRF 50/60Hz Part 1 General Informa�on 1 Indoor and Outdoor Unit Capaci�es 2 External Appearance 3 Combina�on Ra�o...
  • Page 5 56(DC) — — — Notes: Atom series indoor units could connect to Atom series outdoor units. 1.2 Outdoor Units Table 1-1.3: Outdoor unit capacity range Capacity (kBtu/h) Model Name MDV-V12W/DHN1(At) MDV-V18W/DHN1(At) MDV-V21W/DHN1(At) MDV-V28W/DHN1(At) MDV-V36W/DHN1A(At) MDV-V42W/DHN1A(At) MDV-V48W/DHN1(At) MDV-V56W/DHN1(At) MDV-V60W/DHN1(At) Notes: Atom series outdoor units could not be combined.

  • Page 6: External Appearance

    Atom Series VRF 50/60Hz 2 External Appearance 2.1 Indoor Units Table 1-2.1: Indoor unit appearance One-way Casse�e Four-way Casse�e Compact Four-way Casse�e Wall-mounted High Sta�c Pressure Duct Medium Static Pressure Duct Medium Sta�c Pressure Duct (Arc Series Duct) Ceiling and Floor 2.2 Outdoor Units Table 1-2.2: Outdoor unit appearance 12/18/21kBtu/h...
  • Page 7 Atom Series VRF 50/60Hz Combina�on Ra�o Sum of capacity indexes of the indoor units Combina�on ra�o = Capacity index of the outdoor unit Table 1-3.1: Indoor and outdoor unit combination ra�o limitations Type Minimum combina�on ratio Maximum combination ratio Atom Series outdoor units 130% Table 1-3.2: Combina�ons of Indoor and outdoor units Outdoor unit capacity...

  • Page 8: Part 2 Component Layout And Refrigerant Circuits

    Atom Series VRF 50/60Hz Part 2 Component Layout and Refrigerant Circuits 1 Piping Diagrams 8 2 Refrigerant Flow Diagrams...

  • Page 9: Piping Diagrams

    Atom Series VRF 50/60Hz 1 Piping Diagrams Figure 2-1.1: 12/18/21 model piping diagram Liquid pipe Gas pipe Filter Temperature sensor Low pressure switch 4 way valve Temperature sensor Silencer Refrigerant Compressor radiator module return Temperature sensor hole Distributor Temperature sensor Accumulator Electronic Filter...
  • Page 10 Atom Series VRF 50/60Hz Figure 2-1.3: 36 model piping diagram Gas pipe Liquid pipe Filter Temperature sensor Low pressure switch 4 way valve Temperature sensor Refrigerant Oil sepetator radiator Compressor module Temperature sensor High pressure switch Distributor Temperature sensor Accumulator Silencer Filter DC motor...
  • Page 11 Atom Series VRF 50/60Hz Figure 2-1.5: 48/56 model piping diagram Gas pipe Liquid pipe Filter Temperature sensor Low pressure switch Temperature 4 way valve sensor Oil seperator Refrigerant Compressor radiator module Temperature sensor High pressure Temperatu re senso r switch Distributor Accumulator Electronic...

  • Page 12: Refrigerant Flow Diagrams

    Atom Series VRF 50/60Hz 2 Refrigerant Flow Diagrams Cooling opera�on Figure 2-2.1:12/18/21/28/36/42/48/56/60 models refrigerant flow during cooling opera�on Oil return opera�on in cooling mode Figure 2-2.4: 12/18/21/28/36/42/48/56/60 models refrigerant flow during oil return opera�on in cooling mode...
  • Page 13 Atom Series VRF 50/60Hz Hea�ng opera�on Figure 2-2.7: 12/18/21/28/36/42/48/56/60 models refrigerant flow during heating opera�on Oil return opera�on in heating mode Figure 2-2.10: 12/18/21/28/36/42/48/56/60 models refrigerant flow during oil return opera�on in hea�ng mode...
  • Page 14 Atom Series VRF 50/60Hz Defros�ng opera�on Figure 2-2.13: 12/18/21/28/36/42/48/56/60 models refrigerant flow during defros�ng opera�on...
  • Page 15 Atom Series VRF 50/60Hz...

  • Page 16: Part 3 Control

    Atom Series VRF 50/60Hz Part 3 Control 1 General Control Scheme Flowchart 16 2 Stop Opera�on 17 3 Startup Control 17 4 Normal Opera�on Control 5 Protec�on Control 6 Standby Control 20 7 Special Control 21...

  • Page 17: General Control Scheme Flowchart

    Atom Series VRF 50/60Hz 1 General Control Scheme Flowchart Sec�ons 3-2 to 3-7 on the following pages detail when each of the controls in the flowchart below is ac�vated. Stop opera�on ▪ Abnormal shutdown ▪ System stop Thermo on Startup control ▪...

  • Page 18: Startup Control

    Atom Series VRF 50/60Hz 2 Stop Opera�on The stop opera�on occurs for one of the two following reasons: 1. Abnormal shutdown: in order to protect the compressors, if an abnormal state occurs the system makes a 'stop with thermo off' opera�on and an error code is displayed on the outdoor unit digital displays. 2.

  • Page 19: Normal Opera�On Control

    Atom Series VRF 50/60Hz 4 Normal Opera�on Control 4.1 Component Control during Normal Operation Table 3-4.1: Component control during normal cooling opera�on Wiring diagram Component 12-60 model Control func�ons and states label Inverter compressor COMP Controlled according to load requirement ●...

  • Page 20: Protec�On Control

    Atom Series VRF 50/60Hz 5 Protec�on Control 5.1 High Pressure Protec�on Control (exclude model 12/18/21/28) This control protects the system from abnormally high pressure and protects the compressors from transient spikes in pressure. Figure 3-5.1: High pressure protec�on control Normal opera�on >...

  • Page 21: Standby Control

    Atom Series VRF 50/60Hz 5.4 Compressor and Inverter Module Protec�on Control This control protects the compressors from abnormally high currents and protects the inverter modules from abnormally high temperatures. Figure 3-5.4: Compressor current protec�on control Normal opera�on Current ≥ Current Current <...

  • Page 22: Special Control

    Atom Series VRF 50/60Hz 7 Special Control 7.1 Oil Return Operation In order to prevent compressors from running out of oil, the oil return opera�on is conducted to recover oil that has flowed out of the compressor(s) and into the piping system. This opera�on is performed for all units including units that are in standby.
  • Page 23 Atom Series VRF 50/60Hz 7.2 Defros�ng Opera�on In order to recover hea�ng capacity, the defros�ng opera�on is conducted when the outdoor unit heat exchanger is performing as an evaporator. The defrosting opera�on is controlled according to outdoor ambient temperature, outdoor heat exchanger temperature, indoor heat exchanger temperature and outdoor unit running �me.

  • Page 24: Part 4 Field Settings

    Atom Series VRF 50/60Hz Part 4 Field Se�ngs 1 Outdoor Unit Field Se�ngs 24...
  • Page 25 Atom Series VRF 50/60Hz 1 Outdoor Unit Field Se�ngs Figure 4-1.1: 12/18/21/28 model outdoor unit main PCB Figure 4-1.2: 12/18/21/ 28 model outdoor unit communication switchboard...
  • Page 26 Atom Series VRF 50/60Hz Table 4-1.1: 12/18/21/28 model outdoor unit main PCB switch set�ngs Switch Switch Se�ng Description positions Press SW1 to enter the forced cooling func�on; Force cooling Press it again to exit the forced cooling func�on. Spot check Spot check bu�on S1-1 is ON, Forced implementation of old indoor unit protocol S1-1...
  • Page 27 Atom Series VRF 50/60Hz Figure 4-1.3: 36/42/48/56 model outdoor unit main PCB Figure 4-1.4: 36/42/48/56 model outdoor unit communication switchboard...
  • Page 28 Atom Series VRF 50/60Hz Table 4-1.2: 36/42/48/56 model outdoor unit main PCB switch set�ngs Switch Switch Se�ng Description positions Press SW1 to enter the forced cooling func�on; Force cooling press it again to exit the forced cooling func�on. Spot check Spot check bu�on S1-1 is ON, Forced implementation of old IDU protocol S1-1...
  • Page 29 Atom Series VRF 50/60Hz Table 4-1.2: 36/42/48/56 model outdoor unit main PCB switch set�ngs (continued) Switch Switch Se�ng Description positions S4=0000 Network address of ODU: 0(default) S4=1000 Network address of ODU: 1 S4=0100 Network address of ODU: 2 S4=1100 Network address of ODU: 3 S4=0010 Network address of ODU: 4 S4=1010...
  • Page 30 Atom Series VRF 50/60Hz Figure 4-1.3: 60 model outdoor unit main PCB Table 4-1.2: 60 model outdoor unit main PCB switch settings Switch Switch Se�ng Description positions Press SW1 to enter the forced cooling func�on; Force cooling press it again to exit the forced cooling func�on. Spot check Spot check bu�on Network...
  • Page 31 Atom Series VRF 50/60Hz Table 4-1.2: 60 model outdoor unit main PCB switch settings (con�nued) S2=0000 First on priority mode (by default) S2=1000 Cooling priority mode S2=0100 Automatic priority mode S2=1100 In response to hea�ng mode only S2=0010 In response to cooing mode only S2=0110 Hea�ng priority mode S2-4...
  • Page 32 Atom Series VRF 50/60Hz Table 4-1.3: Spot check display table (for all model) Parameters displayed on DSP Remarks Actual value = value displayed Opera�ng frequency Opera�ng mode Refer to Note 1 Opera�ng fan speed level Refer to Note 2 Total capacity requirement of indoor units Total capacity requirement for the modified ODU Actual value = value displayed T3 Condenser...

  • Page 33: Part 5 Electrical Components And Wiring Diagrams

    Atom Series VRF 50/60Hz Part 5 Electrical Components and Wiring Diagrams 1 Outdoor Unit Electric Control Box Layout 33 2 Outdoor Unit Main PCB 3 Wiring Diagrams 41...
  • Page 34 Atom Series VRF 50/60Hz 1 Outdoor Unit Electric Control Box Layout Figure 5-1.1: Front view of 12/18/21/28 model electric control box Power input and power filter Module board PFC inductor IPM module DC fan motor control module Output control assembly Communica�on converter board Figure 5-1.2: Front view of 36/42/48/56 model electric control box Common mode inductor...
  • Page 35 Atom Series VRF 50/60Hz Figure 5-1.3: Front view of 60 model electric control box IPM module Switching power supply module Four-way valve Main control board...

  • Page 36: Outdoor Unit Main Pcb

    Atom Series VRF 50/60Hz 2 Outdoor Unit Main PCB 2.1 Ports Figure 5-2.1: 12/18/21/28 model outdoor unit main PCB ports Table 5-2.1: 12/18/21/28 model main PCB ports Label in Port code Content Port voltage Figure 5-1.1 CN6/CN6-1 Earth Power input AC 220V Power input AC 220V...
  • Page 37 Atom Series VRF 50/60Hz Figure 5-2.2: 36/42/48/56 model outdoor unit main board ports Table 5-2.2: 36/42/48/56 model outdoor unit main board ports Label in Code Content Port voltage Figure 5-1.2 CN27 communica�on port 0-5V DC Main board power supply port; communica�on port between main board 5V DC and 0~5V DC and module board...
  • Page 38 Atom Series VRF 50/60Hz Figure 5-2.3: 12/18/21/28/32/42/48/56 model outdoor unit communica�on converter board PCB Ports Table 5-2.3: 12/18/21/28/32/42/48/56 model communica�on converter board PCB ports Label in Port code Content Port voltage Figure 5-1.3 P Q E X Y E communica�on port 2.5-2.7V DC Digital mul�meter communica�on port 0-5V DC...
  • Page 39 Atom Series VRF 50/60Hz Figure 5-2.4: 60 model outdoor unit main board ports Table 5-2.4: 60 model outdoor unit main board ports Label in Port code Content Port voltage Figure 5-1 CN502 Power input port AC 220V CN501 Power input port AC 220 V Relay control port DC 12V...
  • Page 40 Atom Series VRF 50/60Hz Figure 5-2.5: 60 model outdoor unit filter board Ports Table 5-2.4: 60 model filter board ports Label in Port code Content Port voltage Figure AC Power Input AC 220V AC Power Input AC 220V AC Power Output AC 220V Relay control port DC +12V...
  • Page 41 Atom Series VRF 50/60Hz 2.2 Components 2.2.1 Func�on of bu�ons SW1 to SW2 Table 5-2.5: Func�on of bu�ons SW1 to SW2 Model Bu�on Function Picture Force cooling bu�on 36-60 Check bu�on 2.2.2 Digital display output Table 5-2.6: Digital display output in different opera�ng states Outdoor unit state Parameters displayed on DSP Standby...
  • Page 42 Atom Series VRF 50/60Hz 3 Wiring Diagrams Figure 5-3.1: 12/18/21/28 model wiring diagram Component code Descrip�on Component code Descrip�on CH1-CH6 Magne�c ring STF1 Four-way valve COMP Compressor Refrigerant radiator temperature sensor Electronic expansion valve Power supply terminal DC fan Outdoor heat exchanger temperature sensor HEAT1 Crankcase heater Outdoor ambient temperature sensor...
  • Page 43 Atom Series VRF 50/60Hz Figure 5-3.2: 36/42/48/56 model wiring diagram Component code Descrip�on Component code Descrip�on Rec�fier bridge stacking Relay CH1-CH7 Magne�c ring STF1 Four-way valve COMP. Compressor Outdoor heat exchanger temperature sensor AC current transformer Outdoor ambient temperature sensor D501-D503 Fast-recovery diode Discharge temperature sensor...
  • Page 44 Atom Series VRF 50/60Hz Figure 5-3.3: 60 model wiring diagram Component code Descrip�on Component code Descrip�on 3-slot power supply terminal H-PRO High pressure switch Communica�on converter board L-PRO Low pressure switch CHI-CH6 Magne�c ring STF1 Four-way valve COMP. Compressor Outdoor heat exchanger temperature sensor AC current transformer Outdoor ambient temperature sensor EEV1/EEV2...
  • Page 45 Atom Series VRF 50/60Hz Part 6 Diagnosis and Troubleshoo�ng 1 Error Code Table 46 2 Troubleshoo�ng 47...

  • Page 46: Part 6 Diagnosis And Troubleshoo�Ng

    Atom Series VRF 50/60Hz 1 Error Code Table Table 6-1.1: Error code table Error code Content Note Communica�on fault between main control board and communicate converter board 12-56 models Communica�on fault between main control board and communicate converter board 60 model Communica�on fault between outdoor unit and indoor units All models Outdoor heat exchanger temperature sensor(T3) or outdoor ambient temperature...
  • Page 47 Atom Series VRF 50/60Hz 2 Troubleshoo�ng 2.1 Warning Warning ▪ All electrical work must be carried out by competent and suitably qualified, cer�fied and accredited professionals and in accordance with all applicable legisla�on (all na�onal, local and other laws, standards, codes, rules, regula�ons and other legisla�on that apply in a given situa�on).
  • Page 48 Atom Series VRF 50/60Hz 2.2 C0: Communication fault between main board and communicate converter board (For 12-56 models) 2.2.1 Digital display output 2.2.2 Descrip�on ▪ Communica�on fault between main board and communicate converter board. ▪ The system stops running. ▪ Error code is displayed on the outdoor unit PCB. 2.2.3 Trigger / recover condi�on ▪...
  • Page 49 Atom Series VRF 50/60Hz 2.3 H0: Communica�on fault between main board and communicate converter board (For 60 model) 2.3.1 Digital display output 2.3.2 Descrip�on ▪ Communica�on fault between main board and motor control module. 2.3.3 Trigger / recover condi�on ▪ Trigger condi�on: Motor control module and ODU main control board cannot communicate. ▪...
  • Page 50 Atom Series VRF 50/60Hz 2.4 E2: Communica�on error between outdoor unit and indoor units (For all models) 2.4.1 Digital display output 2.4.2 Descrip�on ▪ Communica�on error between outdoor unit and indoor units. ▪ The system stops running. ▪ Error code is displayed on the outdoor unit PCB. 2.4.3 Trigger / recover condi�on ▪...
  • Page 51 Atom Series VRF 50/60Hz 2.4.5 Procedure Communica�on wires P Q E have short Reconnect the communication wires circuited or disconnected Communica�on wires P Q E are not Connect the communica�on wires in a connected in a daisy chain daisy chain IDU power supply is abnormal Ensure normal power supply Wires between outdoor main PCB and...
  • Page 52 Atom Series VRF 50/60Hz 2.5 E4: Temperature sensor (T3/T4) fault (For all models) 2.5.1 Digital display output 2.5.2 Descrip�on ▪ Outdoor heat exchanger temperature sensor (T3) error or outdoor ambient temperature sensor (T4) error. ▪ The system stops running. ▪ Error code is displayed on the outdoor unit PCB. 2.5.3 Trigger / recover condi�on ▪...
  • Page 53 Atom Series VRF 50/60Hz 2.6 E5: Abnormal power supply voltage (For all models) 2.6.1 Digital display output 2.6.2 Descrip�on ▪ Abnormal power supply voltage. ▪ The system stops running. ▪ Error code is displayed on the outdoor unit PCB. 2.6.3 Trigger / recover condi�on ▪...
  • Page 54 Atom Series VRF 50/60Hz 2.7 E6: DC fan motor error; Eb: E6 protec�on appears 6 �mes in one hour (For all models) 2.7.1 Digital display output E6 or Eb 2.7.2 Descrip�on ▪ E6:DC fan motor error; Eb: E6 protec�on appears 6 �mes in one hour ▪...
  • Page 55 Atom Series VRF 50/60Hz 2.8 E9: EEPROM error (For all models) 2.8.1 Digital display output 2.8.2 Descrip�on ▪ EEPROM error ▪ The system stops running. ▪ Error code is displayed on the outdoor unit PCB. 2.8.3 Trigger / recover condi�on ▪...
  • Page 56 Atom Series VRF 50/60Hz 2.9 E.9.: Compressor parameters mismatch (For all models) 2.9.1 Digital display output E.9. 2.9.2 Descrip�on ▪ Main control chip detect the power set�ng number mismatch the model, the unit will display E.9. error. ▪ The system stops running. ▪...
  • Page 57 Atom Series VRF 50/60Hz 2.10 EF: PFC fault (For all models) 2.10.1 Digital display output 2.10.2 Descrip�on ▪ PFC fault protec�on. ▪ The system stops running. ▪ Error code is displayed on the outdoor unit PCB. 2.10.3 Trigger / recover condi�on ▪...
  • Page 58 Atom Series VRF 50/60Hz 2.11 EH: Refrigerant radiator temperature sensor error (For all models) 2.11.1 Digital display output 2.11.2 Descrip�on ▪ Refrigerant radiator temperature TL sensor error. ▪ The system stops running. ▪ Error code is displayed on outdoor unit PCB. 2.11.3 Trigger / recover condi�on ▪...
  • Page 59 Atom Series VRF 50/60Hz 2.12 EP: Outdoor ambient temperature is lower than -15 in cooling opera�on (For all models) ℃ 2.12.1 Digital display output 2.12.2 Descrip�on ▪ Outdoor ambient temperature is lower than -15℃ in cooling opera�on. ▪ The system stops running. ▪...
  • Page 60 Atom Series VRF 50/60Hz 2.13 F1: DC bus voltage protec�on (for all models) 2.13.1 Digital display output 2.13.2 Descrip�on ▪ F1 indicates DC bus voltage protec�on. ▪ The system stops running. ▪ Error code is displayed on the outdoor unit PCB. 2.13.3 Trigger / recover condi�on ▪...
  • Page 61 Atom Series VRF 50/60Hz 2.14 H4: L (L0/L1) fault occurs three �mes in one hour (For all models) 2.14.1 Digital display output 2.14.2 Descrip�on ▪ The L (L0/L1) fault occurs three �mes in one hour. ▪ The system stops running. ▪...
  • Page 62 Atom Series VRF 50/60Hz 2.15 H7: The number of online indoor units have decreased/increased (For all models) 2.15.1 Digital display output 2.15.2 Descrip�on ▪ The number of online indoor units have decreased/increased. ▪ The system stops running. ▪ Error code is displayed on the unit with the error. 2.15.3 Trigger / recover condi�on ▪...
  • Page 63 Atom Series VRF 50/60Hz 2.16 HF: Indoor unit and outdoor unit program mismatch (For all models) 2.16.1 Digital display output 2.16.2 Descrip�on ▪ Indoor unit and outdoor unit program mismatch. ▪ The system stops running. ▪ Error code is displayed on the unit with the error. 2.16.3 Trigger / recover condi�on ▪...
  • Page 64 Atom Series VRF 50/60Hz 2.17 PL: Radiator surface high temperature protection (For all models) 2.17.1 Digital display output 2.17.2 Descrip�on ▪ Radiator surface high temperature protection. ▪ The system stops running. ▪ Error code is displayed on outdoor unit PCB. 2.17.3 Trigger / recover condi�on ▪...
  • Page 65 Atom Series VRF 50/60Hz 2.18 P1: Discharge pipe high pressure protec�on (For all models) 2.18.1 Digital display output 2.18.2 Descrip�on ▪ Discharge pipe high pressure protec�on. ▪ The system stops running. ▪ Error code is displayed on the outdoor unit PCB. 2.18.3 Trigger / recover condi�on ▪...
  • Page 66 Atom Series VRF 50/60Hz 2.18.5 Procedure High pressure sensor connec�on on main Ensure the sensor is connected properly PCB is loose High pressure sensor has short-circuited or Replace the sensor failed Discharge part of the refrigerant. Add oil if Excess refrigerant it leaks during discharge Flush all refrigerant then vacuum the System contains air or nitrogen...
  • Page 67 Atom Series VRF 50/60Hz 2.19 P2: Suc�on pipe low pressure protec�on (For all models) 2.19.1 Digital display output 2.19.2 Descrip�on ▪ Suc�on pipe low pressure protec�on. ▪ The system stops running. ▪ Error code is displayed on outdoor unit PCB. 2.19.3 Trigger / recover condi�on ▪...
  • Page 68 Atom Series VRF 50/60Hz 2.19.5 Procedure the outdoor ambient temperature is too Stop the unit Low pressure sensor connection on main Ensure the sensor is connected properly PCB is loose Low pressure sensor has short-circuited or Replace the sensor failed Insufficient refrigerant caused by Add refrigerant or inspect the system for refrigerant leakage...
  • Page 69 Atom Series VRF 50/60Hz 2.17 P3: Compressor current protec�on (For all models) 2.19.6 Digital display output 2.19.7 Descrip�on ▪ P3 indicates current protection on compressor. ▪ The system stops running. ▪ Error code is displayed on the outdoor unit PCB. 2.19.8 Trigger / recover condi�on ▪...
  • Page 70 Atom Series VRF 50/60Hz The condenser heat exchange is poor Inspect the system and fix the error The high pressure side is blocked, caused Inspect the system and fix the error by crushed or bent pipe or blocked EXV Inverter module has short-circuited Replace the inverter module Compressor has malfunc�oned Replace the compressor...
  • Page 71 Atom Series VRF 50/60Hz 2.18 P4: Discharge temperature protection (For all models) 2.18.1 Digital display output 2.18.2 Descrip�on ▪ Discharge temperature protec�on. ▪ The system stops running. ▪ Error code is displayed on the unit with the error. 2.18.3 Trigger / recover condi�on ▪...
  • Page 72 Atom Series VRF 50/60Hz 2.18.5 Procedure Discharge pipe temperature sensor Ensure the sensors and switch are connected and/or discharge temperature switch properly connec�ons on main PCB are loose Compressor top temperature sensor and/or discharge pipe temperature Replace the faulty sensor(s) sensor have short circuited or failed Insufficient refrigerant caused by Add refrigerant and inspect the system for leaks...
  • Page 73 Atom Series VRF 50/60Hz 2.19 P5: Outdoor heat exchanger temperature protec�on (For all models) 2.19.1 Digital display output 2.19.2 Descrip�on ▪ Outdoor heat exchanger temperature protec�on. ▪ The system stops running. ▪ Error code is displayed on the unit with the error. 2.19.3 Trigger / recover condi�on ▪...
  • Page 74 Atom Series VRF 50/60Hz 2.19.5 Procedure Outdoor heat exchanger temperature Ensure the sensor is connected properly sensor connec�on on main PCB is loose Outdoor heat exchanger temperature Replace the sensor sensor has short-circuited or failed Make sure the combina�on ra�o is less than The indoor load is too large 130% Flush all refrigerant then vacuum the system and...
  • Page 75 Atom Series VRF 50/60Hz 2.20 P8: Typhoon protec�on (For all models) 2.20.1 Digital display output 2.20.2 Descrip�on ▪ P8 indicates strong wind protec�on. ▪ The system stops running. ▪ Error code is displayed on the outdoor unit PCB. 2.20.3 Trigger / recover condi�on ▪...
  • Page 76 Atom Series VRF 50/60Hz 2.21 P9: Poor reversing of four-way valve (For all models) 2.21.1 Digital display output 2.21.2 Descrip�on ▪ P9 indicates poor reversing of four-way valve. ▪ The system stops running. ▪ Error code is displayed on the outdoor unit PCB. 2.21.3 Trigger / recover condi�on ▪...
  • Page 77 Atom Series VRF 50/60Hz 2.22 PE: Evaporator high temperature protec�on (For all models) 2.22.1 Digital display output 2.22.2 Descrip�on ▪ Evaporator high temperature protec�on ▪ The system stops running. ▪ Error code is displayed on the outdoor unit PCB. 2.22.3 Trigger / recover condi�on ▪...
  • Page 78 Atom Series VRF 50/60Hz 2.23 PF: Outdoor Unit Locked 2.23.1 Digital display output 2.23.2 Descrip�on ▪ Outdoor unit is locked and cannot be used. 2.23.3 Possible causes ▪ Outdoor unit is locked and password is not entered to unlock. ▪ Main PCB damaged 2.23.4 Procedure Outdoor units whether to enter the Enter the password to unlock the state...
  • Page 79 Atom Series VRF 50/60Hz 2.24 L0/L1/L2/L3/L4/L5/L7/L8/L9: L category of inverter module protec�on (For all models) 2.24.1 Digital display output L0/L1/L2/L3/L4/L5/L7/L8/L9 2.24.2 Descrip�on ▪ Compressor inverter module protec�on. ▪ The system stops running. ▪ Error code is displayed on the outdoor unit PCB. 2.24.3 Trigger / recover condi�on ▪...
  • Page 80 Atom Series VRF 50/60Hz 2.24.6 L5: Zero speed protec�on There is abnormal noise of Replace the compressor compressor when startup or running Replace the inverter module 2.24.7 L7: Phase sequence error Reconnect cables based Compressor wiring is loose on wiring diagram An open circuit in the 3-phase U/V/W Replace the compressor of compressor terminals...
  • Page 81 Atom Series VRF 50/60Hz 2.24.8 L8 / L9 troubleshoo�ng L8/L9 Reconnect the cables based on Compressor wiring is not properly wiring diagram The resistance between 3 phases of compressor is over 5Ω Replace the compressor The insula�on resistance of compressor is less than 100Ω The compressor has less than 12 hours prehea�ng before ini�al Ensure enough prehea�ng �me...
  • Page 82 Atom Series VRF 50/60Hz 2.24.9 L1: DC bus low voltage protec�on Voltage of power supply is 166-265V? Provide normal power supply Check the wiring between main control board and Connect again filter board is correct or not. Repower on and wai�ng for 10S,and then test the voltage of CN4 port "RL"...
  • Page 83 Atom Series VRF 50/60Hz 2.24.2 Compressor replacement procedure Step 1: Remove faulty compressor and remove oil ▪ Remove the faulty compressor from the outdoor unit. ▪ Before removing the oil, shake the compressor so as to not allow impuri�es to remain settled at the bottom. ▪...
  • Page 84 Atom Series VRF 50/60Hz 2.24.3 Specific error codes for inverter module protec�on The specific error codes L0, L1, L2, L4, L5, L7, L8 and L9 can also be obtained from the inverter module LED indicators. If an inverter module error has occurred, one of inverter module LED indicators is con�nuously on and the other one of inverter module LED indicators flashes Table 6-2.3: Errors indicated on LED LED flashing pattern...
  • Page 85 Ver. 2023-08 Professional Equipment Midea Group Add.: Midea Headquarters Building, 6 Midea Avenue, Shunde, Foshan, Guangdong, China Postal code: 528311 mbt.midea.com / global.midea.com Note: Product specifica�ons change from �me to �me as product improvements and developments are released and may vary from those in this document.

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