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Midea ATOM B Series Service Manual
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Midea ATOM B Series Service Manual

Commercial air conditioners
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Service
Manual
 
Model: 
 
B Series
MDV‐V28WDHN1(AtB)
MDV‐V36WDHN1(AtB)
MDV‐V42WDHN1(AtB)
MDV‐V48WDHN1(AtB)
MDV‐V56WDHN1(AtB)
MDV‐V60WDHN1(AtB)
Commercial Air Conditioners
R410A

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Summary of Contents for Midea ATOM B Series

  • Page 1   R410A Commercial Air Conditioners   Service Manual   B Series Model:  MDV‐V28WDHN1(AtB) MDV‐V36WDHN1(AtB) MDV‐V42WDHN1(AtB) MDV‐V48WDHN1(AtB) MDV‐V56WDHN1(AtB) MDV‐V60WDHN1(AtB)
  • Page 2 Atom B Series VRF 50/60Hz         CONTENTS      Part  1  General  Information  ................ 3   Part  2  Component  Layout  and  Refrigerant  Circuits ........ 7   Part  3  Control .................... 15  Part  4  Field  Settings  .................. 23  Part  5  Electrical  Components  and  Wiring  Diagrams ........ 32  Part  6  Diagnosis  and  Troubleshooting  ............ 45  ...
  • Page 3 Atom B Series VRF 50/60Hz           2     ...
  • Page 4 Atom B Series VRF 50/60Hz Part 1 General Information 1 Indoor and Outdoor Unit Capacities ............4 2 External Appearance .................. 5 3 Combination Ratio ..................6...
  • Page 5 Atom B Series VRF 50/60Hz 1 Indoor and Outdoor Unit Capacities 1.1 Indoor Units Table 1-1.1: Indoor unit abbreviation codes Abbreviation code Type One-way Cassette Compact Four-way Cassette Four-way Cassette High Static Pressure Duct Medium Static Pressure Duct Wall-mounted Ceiling and Floor Table 1-1.2: Indoor unit capacity range...
  • Page 6 Atom B Series VRF 50/60Hz 2 External Appearance 2.1 Indoor Units Table 1-2.1: Indoor unit appearance One-way Cassette Four-way Cassette Compact Four-way Cassette Wall-mounted High Static Pressure Duct Medium Static Pressure Duct Medium Static Pressure Duct (Arc Series Duct) Ceiling and Floor 2.2 Outdoor Units...
  • Page 7 Atom B Series VRF 50/60Hz 3 Combination Ratio Sum of capacity indexes of the indoor units Combination ratio = Capacity index of the outdoor unit Table 1-3.1: Indoor and outdoor unit combination ratio limitations Type Minimum combination ratio Maximum combination ratio...
  • Page 8   Atom B Series VRF 50/60Hz ‐i      Part 2  Component Layout and  Refrigerant Circuits    1 Piping Diagrams .................. 8   2 Refrigerant Flow Diagrams ............... 11             7 ...
  • Page 9 Atom B Series VRF 50/60Hz           1 Piping Diagrams    Figure 2‐1.1: 28 model piping diagram Gas pipe Liquid pipe Filter Temperature sensor Low pressure switch Temperature 4 way valve sensor Oil seperator Refrigerant Compressor radiator module return Temperature hole sensor Distributor Temperature sensor Accumulator Filter DC motor Oil return capiliary  ...
  • Page 10   Atom B Series VRF 50/60Hz ‐i        Figure 2‐1.3: 42 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 expansion valve Oil return capiliar y...
  • Page 11 Atom B Series VRF 50/60Hz             Figure 2‐1.3: 60 model piping diagram Gas pipe Liquid pipe Filter Temperature sense Low pressure switch 4 way valve Temperature sense Oil seperator Refrigerant Compressor radiator modile Temperature sense High pressure switch Distributor Temperature sense Silencer（Reserved） Oil return capiliary DC motor  ...
  • Page 12   Atom B Series VRF 50/60Hz ‐i      2 Refrigerant Flow Diagrams  Cooling operation     Figure 2‐2.1:28/36/42/48/56/60 models refrigerant flow during cooling operation   Oil return operation in cooling mode    Figure 2‐2.4: 28/36/42/48/56/60 models refrigerant flow during oil return operation in cooling mode           11 ...
  • Page 13 Atom B Series VRF 50/60Hz           Heating operation    Figure 2‐2.7: 28/36/42/48/56/60 models refrigerant flow during heating operation     Oil return operation in heating mode    Figure 2‐2.10: 28/36/42/48/56/60 models refrigerant flow during oil return operation in heating mode       12     ...
  • Page 14   Atom B Series VRF 50/60Hz ‐i      Defrosting operation  Figure 2‐2.13: 28/36/42/48/56/60 models refrigerant flow during defrosting operation            13 ...
  • Page 15 Atom B Series VRF 50/60Hz             14     ...

  • Page 16: Table Of Contents

    Atom B Series VRF 50/60Hz       Part 3  Control    1 General Control Scheme Flowchart ............ 16   2 Stop Operation .................. 17   3 Startup Control .................. 17   4 Normal Operation Control ............... 18   5 Protection Control ................... 19   6 Special Control  .................. 21             15 ...

  • Page 17: 1 General Control Scheme Flowchart

    Atom B Series VRF 50/60Hz         1 General Control Scheme Flowchart  Sections 3-2 to 3-7 on the following pages detail when each of the controls in the flowchart below is activated.    2  Stop operation   Abnormal shutdown   System stop  Thermo on  3  Startup control   Compressor startup delay control     Startup control for cooling operation   Startup control for heating operation  6  Special control  4  Normal operation control  Conditions met   Component control during normal operation  for oil return   Oil return operation   Compressor output control  Conditions met   Compressor step control  for defrosting ...

  • Page 18: 2 Stop Operation

    Atom B Series VRF 50/60Hz       2 Stop Operation  The stop operation 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' operation and an error code is displayed on the outdoor unit digital displays.  2. The system stops when the set temperature has been reached.    3 Startup Control  3.1 Compressor Startup Delay Control  When the ODU is powered on again and the compressor delays about 7 minutes to start. After the compressor stops running,  it takes about 4 minutes to restart, in order to prevent frequent compressor on/off and to equalize the pressure within the  refrigerant system.  3.2 Startup Control for Cooling Operation  Table 3‐3.1: Component control during startup in cooling mode  Wiring  Component  28‐60 model  Control functions and states  diagram label  Controlled  according  to  load  requirement,  operating  Inverter compressor    COMP    ● frequency increased by 1 step / sec  The outdoor unit fan start by 14 gears for 20 seconds before ...

  • Page 19: 4 Normal Operation Control

    Atom B Series VRF 50/60Hz         4 Normal Operation Control  4.1 Component Control during Normal Operation  Table 3‐4.1: Component control during normal cooling operation  Wiring diagram  Component  28‐60 model  Control functions and states  label  Inverter compressor    COMP    Controlled according to load requirement  ● Fan speed controlled according to heat exchanger temperature    DC fan motor    FAN  ● (T3),  outdoor  ambient  temperature  (T4),discharge  temperature  (T5)and compressor frequency.  Electronic expansion valve    EEV  ● Controlled according to discharge temperature  Four-way valve  ST1 ...

  • Page 20: 5 Protection Control

    Atom B Series VRF 50/60Hz       5 Protection Control  5.1 High Pressure Protection Control (exclude model 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 protection control Normal operation  > 4.4MPa  < 3.2MPa High pressure protection, error code P1 is displayed Notes:      1. P : Discharge pressure When the discharge pressure rises above 4.4MPa the system displays P1 protection and the unit stops running. When the  discharge pressure drops below 3.2MPa, the compressor enters re-start control.    5.2 Low Pressure Protection Control ...
  • Page 21 Atom B Series VRF 50/60Hz         5.4 Compressor and Inverter Module Protection 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 protection control Normal operation Current ≥ Current Current < Current Compressor current protection, error code P3 is displayed       5.5 Disable Cooling Control  When  the  outdoor  ambient  temperature  drops  below  or  equal  to  -15°C，  cooling  mode  is  disabled  to  prevent  low  compression ratios which can result in insufficient compressor internal oil lubrication, and prevent humid compressed in low  superheat of compressor bottom conditions. When the outdoor ambient temperature rises above or equal to -14°C, the ...

  • Page 22: 6 Special Control

    Atom B Series VRF 50/60Hz       6 Special Control  6.1 Oil Return Operation  In order to prevent compressors from running out of oil, the oil return operation is conducted to recover oil that has flowed  out of the compressor(s) and into the piping system. This operation is performed for all units including units that are in  standby.    Timing of oil return operation:   When the initial cumulative operating time reaches every 8 hours.  Tables 3-6.1 and 3-6.2 show component control during oil return operation in cooling mode.    Table 3‐6.1: Outdoor unit component control during oil return operation in cooling mode Wiring diagram  Component  28‐60 model  Control functions and states  label  Inverter compressor    COMP    Fixed frequency  ● DC fan motor    FAN  ● Normal control as cooling operation  Electronic expansion valve    EEV1  ● Position 300 (steps)  Four-way valve  ST1 ...
  • Page 23 Atom B Series VRF 50/60Hz         6.2 Defrosting Operation  In  order  to  recover  heating  capacity,  the  defrosting  operation  is  conducted  when  the  outdoor  unit  heat  exchanger  is  performing as an evaporator. The defrosting operation is controlled according to outdoor ambient temperature, outdoor  heat exchanger temperature, indoor heat exchanger temperature and outdoor unit running time. When the outdoor unit is  running in defrosting, the digital display on outdoor main PCB will display “df”.    Table 3‐6.5: Outdoor unit component control during defrosting operation Wiring diagram  Component  28‐60 model Control functions and states  label  Inverter compressor    COMP    Fixed frequency  ●...
  • Page 24 Atom B Series VRF 50/60Hz Part 4 Field Settings 1 Outdoor Unit Field Settings ..............24...
  • Page 25 Atom B Series VRF 50/60Hz 1 Outdoor Unit Field Settings Figure 4-1.1: 28 model outdoor unit main PCB Figure 4-1.2: 28 model outdoor unit communication switchboard...
  • Page 26 Atom B Series VRF 50/60Hz Table 4-1.1: 28 model outdoor unit main PCB switch settings Switch Switch Setting Description positions Press SW1 to enter the forced cooling function; Force cooling Press it again to exit the forced cooling function. Spot check...
  • Page 27 Atom B 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 B Series VRF 50/60Hz Table 4-1.2: 36/42/48/56 model outdoor unit main PCB switch settings Switch Switch Setting Description positions Press SW1 to enter the forced cooling function; Force cooling press it again to exit the forced cooling function. Spot check...
  • Page 29 Atom B Series VRF 50/60Hz Table 4-1.2: 36/42/48/56 model outdoor unit main PCB switch settings (continued) Switch Switch Setting 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...
  • Page 30 Atom B 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 Setting Description positions Press SW1 to enter the forced cooling function; Force cooling press it again to exit the forced cooling function.
  • Page 31 Atom B Series VRF 50/60Hz Table 4-1.2: 60 model outdoor unit main PCB switch settings (continued) S2=0000 First on priority mode (by default) S2=1000 Cooling priority mode S2=0100 Automatic priority mode S2=1100 In response to heating mode only S2=0010 In response to cooing mode only...
  • Page 32 Atom B Series VRF 50/60Hz Table 4-1.3: Spot check display table (for all model) Parameters displayed on DSP Remarks Actual value = value displayed Operating frequency Operating mode Refer to Note 1 Operating fan speed level Refer to Note 2...
  • Page 33 Atom B Series VRF 50/60Hz Part 5 Electrical Components and Wiring Diagrams 1 Outdoor Unit Electric Control Box Layout ..........33 2 Outdoor Unit Main PCB ................35 3 Wiring Diagrams ..................42...
  • Page 34 Atom B Series VRF 50/60Hz 1 Outdoor Unit Electric Control Box Layout Figure 5-1.1: Front view of 28 model electric control box Power input and power filter Module board PFC module IPM module DC fan motor control module Output control assembly Main control board Figure 5-1.2: Front view of 36/42/48/56 model electric control box...
  • Page 35 Atom B Series VRF 50/60Hz Figure 5-1.3: Front view of 60 model electric control box Switching IPM module power supply module Power supply Power supply and Main control board power filter...
  • Page 36 Atom B Series VRF 50/60Hz 2 Outdoor Unit Main PCB 2.1 Ports Figure 5-2.1: 28 model outdoor unit main PCB ports Table 5-2.1: 28 model main PCB ports Label in Port code Content Port voltage Figure 5-1.1 CN6/CN6-1 Earth Power input...
  • Page 37 Atom B 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 communication port 0-5V DC Main board power supply port;...
  • Page 38 Atom B Series VRF 50/60Hz Figure 5-2.3: 28/36/42/48/56 model outdoor unit Communication converter board PCB Ports Table 5-2.3: 28/36/42/48/56 model communication converter board PCB ports Label in Port code Content Port voltage Figure 5-1.3 P Q E X Y E communication port 2.5-2.7V DC...
  • Page 39 Atom B 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...
  • Page 40 Atom B 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...
  • Page 41 Atom B Series VRF 50/60Hz 2.2 Components 2.2.1 LED indicator Table 5-2.5: LED indicator Indicator LED indicator function and status Inverter module operating indicator (red light). Continuously on if the compressor is LED101 running normally, quick flashing (5Hz) if an inverter module error has occurred slow flashing (1Hz) if the machine is in standby mode.
  • Page 42 Atom B Series VRF 50/60Hz 2.2.3 System check button On pressing Spot check button, the parameters listed in Table 5-2.6 will be displayed in sequence. Table 5-2.7: 28/36/42/48/56/60 model system check Parameters displayed on DSP Remarks Actual value = value displayed...
  • Page 43 Atom B Series VRF 50/60Hz 3 Wiring Diagrams Figure 5-3.1: 28 model wiring diagram Component code Description Component code Description CH1-CH4 Magnetic ring STF1 Four-way valve COMP Compressor Refrigerant radiator temperature sensor EEV1 Electronic expansion valve Power supply terminal DC fan...
  • Page 44 Atom B Series VRF 50/60Hz Figure 5-3.2: 36/42/48/56 model wiring diagram Component code Description Component code Description Rectifier bridge stacking Relay CH1-CH7 Magnetic ring STF1 Four-way valve COMP. Compressor Outdoor heat exchanger temperature sensor AC current transformer Outdoor ambient temperature sensor...
  • Page 45 Atom B Series VRF 50/60Hz Figure 5-3.3: 60 model wiring diagram Component code Description Component code Description 3-slot power supply terminal H-PRO High pressure switch Communication converter board L-PRO Low pressure switch CHI-CH6 Magnetic ring STF1 Four-way valve COMP. Compressor...
  • Page 46 Atom B Series VRF 50/60Hz Part 6 Diagnosis and Troubleshooting 1 Error Code Table ..................46 2 Troubleshooting ..................47...
  • Page 47 Atom B Series VRF 50/60Hz 1 Error Code Table Table 6-1.1: Error code table Error code Content Note Communication fault between main control board and communicate converter board 28-56 models Communication fault between main control board and communicate converter board...
  • Page 48 Atom B Series VRF 50/60Hz 2 Troubleshooting 2.1 Warning Warning  All electrical work must be carried out by competent and suitably qualified, certified and accredited professionals and in accordance with all applicable legislation (all national, local and other laws, standards, codes, rules, regulations and other legislation that apply in a given situation).
  • Page 49 Atom B Series VRF 50/60Hz 2.2 C0: Communication fault between main board and communicate converter board (For 28-56 models) 2.2.1 Digital display output 2.2.2 Description  Communication fault between main board and communicate converter board.  The system stops running.
  • Page 50 Atom B Series VRF 50/60Hz 2.3 H0: Communication fault between main board and communicate converter board (For 60 model) 2.3.1 Digital display output 2.3.2 Description  Communication fault between main board and motor control module. 2.3.3 Trigger / recover condition ...
  • Page 51 Atom B Series VRF 50/60Hz 2.4 E2: Communication error between outdoor unit and indoor units (For all models) 2.4.1 Digital display output 2.4.2 Description  Communication error between outdoor unit and indoor units.  The system stops running.  Error code is displayed on the outdoor unit PCB.
  • Page 52 Atom B Series VRF 50/60Hz 2.4.5 Procedure Communication wires P Q E have short Reconnect the communication wires circuited or disconnected Communication wires P Q E are not Connect the communication wires in a connected in a daisy chain daisy chain...
  • Page 53 Atom B Series VRF 50/60Hz Switch Switch positions Description S1-2 is ON, forced clearing of IDU address S1-2 is OFF, Automatic addressing(default)  Press indoor unit’s receiver button for 5 seconds, the indoor unit’s communication address code is displayed. Table 6-2.1: Communication address code...
  • Page 54 Atom B Series VRF 50/60Hz 2.5 E4: Temperature sensor (T3/T4) fault (For all models) 2.5.1 Digital display output 2.5.2 Description  Outdoor heat exchanger temperature sensor (T3) error or outdoor ambient temperature sensor (T4) error.  The system stops running.
  • Page 55 Atom B Series VRF 50/60Hz 2.6 E5: Abnormal power supply voltage (For all models) 2.6.1 Digital display output 2.6.2 Description  Abnormal power supply voltage.  The system stops running.  Error code is displayed on the outdoor unit PCB.
  • Page 56 Atom B Series VRF 50/60Hz 2.7 E6: DC fan motor error; Eb: E6 protection appears 6 times in one hour (For all models) 2.7.1 Digital display output E6 or Eb 2.7.2 Description  E6:DC fan motor error; Eb: E6 protection appears 6 times in one hour ...
  • Page 57 Atom B Series VRF 50/60Hz 2.8 E9: EEPROM error (For all models) 2.8.1 Digital display output 2.8.2 Description  EEPROM error  The system stops running.  Error code is displayed on the outdoor unit PCB. 2.8.3 Trigger / recover condition ...
  • Page 58 Atom B 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 Description  Main control chip detect the power setting number mismatch the model, the unit will display E.9. error.  The system stops running.
  • Page 59 Atom B Series VRF 50/60Hz 2.10 EF: PFC fault (For all models) 2.10.1 Digital display output 2.10.2 Description  PFC fault protection.  The system stops running.  Error code is displayed on the outdoor unit PCB. 2.10.3 Trigger / recover condition ...
  • Page 60 Atom B Series VRF 50/60Hz 2.11 EH: Refrigerant radiator temperature sensor error (For all models) 2.11.1 Digital display output 2.11.2 Description  Refrigerant radiator temperature TL sensor error.  The system stops running.  Error code is displayed on outdoor unit PCB.
  • Page 61 Atom B Series VRF 50/60Hz ℃ 2.12 EP: Outdoor ambient temperature is lower than -15 in cooling operation (For all models) 2.12.1 Digital display output 2.12.2 Description  Outdoor ambient temperature is lower than -15℃ in cooling operation.  The system stops running.
  • Page 62 Atom B Series VRF 50/60Hz 2.13 F1: DC bus voltage protection (for all models) 2.13.1 Digital display output 2.13.2 Description  F1 indicates DC bus voltage protection.  The system stops running.  Error code is displayed on the outdoor unit PCB.
  • Page 63 Atom B Series VRF 50/60Hz 2.14 H4: L (L0/L1) fault occurs three times in one hour (For all models) 2.14.1 Digital display output 2.14.2 Description  The L (L0/L1) fault occurs three times in one hour.  The system stops running.
  • Page 64 Atom B 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 Description  The number of online indoor units have decreased/increased.  The system stops running.  Error code is displayed on the unit with the error.
  • Page 65 Atom B 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 Description  Indoor unit and outdoor unit program mismatch.  The system stops running.  Error code is displayed on the unit with the error.
  • Page 66 Atom B Series VRF 50/60Hz 2.17 PL: Radiator surface high temperature protection (For all models) 2.17.1 Digital display output 2.17.2 Description  Radiator surface high temperature protection.  The system stops running.  Error code is displayed on outdoor unit PCB.
  • Page 67 Atom B Series VRF 50/60Hz 2.18 P1: Discharge pipe high pressure protection (For all models) 2.18.1 Digital display output 2.18.2 Description  Discharge pipe high pressure protection.  The system stops running.  Error code is displayed on the outdoor unit PCB.
  • Page 68 Atom B Series VRF 50/60Hz 2.18.5 Procedure High pressure sensor connection 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...
  • Page 69 Atom B Series VRF 50/60Hz 2.19 P2: Suction pipe low pressure protection (For all models) 2.19.1 Digital display output 2.19.2 Description  Suction pipe low pressure protection.  The system stops running.  Error code is displayed on outdoor unit PCB.
  • Page 70 Atom B 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...
  • Page 71 Atom B Series VRF 50/60Hz 2.17 P3: Compressor current protection (For all models) 2.19.6 Digital display output 2.19.7 Description  P3 indicates current protection on compressor.  The system stops running.  Error code is displayed on the outdoor unit PCB.
  • Page 72 Atom B 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...
  • Page 73 Atom B Series VRF 50/60Hz 2.18 P4: Discharge temperature protection (For all models) 2.18.1 Digital display output 2.18.2 Description  Discharge temperature protection.  The system stops running.  Error code is displayed on the unit with the error. 2.18.3 Trigger / recover condition ...
  • Page 74 Atom B 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 connections on main PCB are loose Compressor top temperature sensor and/or discharge pipe temperature Replace the faulty sensor(s)
  • Page 75 Atom B Series VRF 50/60Hz 2.19 P5: Outdoor heat exchanger temperature protection (For all models) 2.19.1 Digital display output 2.19.2 Description  Outdoor heat exchanger temperature protection.  The system stops running.  Error code is displayed on the unit with the error.
  • Page 76 Atom B Series VRF 50/60Hz 2.19.5 Procedure Outdoor heat exchanger temperature Ensure the sensor is connected properly sensor connection on main PCB is loose Outdoor heat exchanger temperature Replace the sensor sensor has short-circuited or failed Make sure the combination ratio is less than...
  • Page 77 Atom B Series VRF 50/60Hz 2.20 P8: Typhoon protection (For all models) 2.20.1 Digital display output 2.20.2 Description  P8 indicates strong wind protection.  The system stops running.  Error code is displayed on the outdoor unit PCB. 2.20.3 Trigger / recover condition ...
  • Page 78 Atom B 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 Description  P9 indicates poor reversing of four-way valve.  The system stops running.  Error code is displayed on the outdoor unit PCB.
  • Page 79 Atom B Series VRF 50/60Hz 2.22 PE: Evaporator high temperature protection (For all models) 2.22.1 Digital display output 2.22.2 Description  Evaporator high temperature protection  The system stops running.  Error code is displayed on the outdoor unit PCB.
  • Page 80 Atom B Series VRF 50/60Hz 2.23 L0/L1/L2/L4/L5/L7/L8/L9: L category of inverter module protection (For all models) 2.23.1 Digital display output L0/L1/L2/L4/L5/L7/L8/L9 2.23.2 Description  Compressor inverter module protection.  The system stops running.  Error code is displayed on the outdoor unit PCB.
  • Page 81 Atom B Series VRF 50/60Hz 2.23.6 L5: Zero speed protection There is abnormal noise of Replace the compressor compressor when startup or running Replace the inverter module 2.23.7 L7: Phase sequence error Reconnect cables based Compressor wiring is loose on wiring diagram...
  • Page 82 Atom B Series VRF 50/60Hz 2.23.8 L8 / L9 troubleshooting 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 insulation resistance of compressor is less than 100Ω...
  • Page 83 Atom B Series VRF 50/60Hz 2.23.9 L1: DC bus low voltage protection 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 waiting for 10S,and then test the voltage of CN4 port "RL"...
  • Page 84 Atom B Series VRF 50/60Hz 2.23.11 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 impurities to remain settled at the bottom.
  • Page 85 Atom B Series VRF 50/60Hz 2.23.12 Specific error codes for inverter module protection The specific error codes L0, L1, L2, L4, L5, L7, L8 and L9 can alsobe obtained from the inverter module LED indicators. If an inverter module error has occurred, one of inverter module LED indicators is continuously on and the other one of inverter module LED indicators flashes Table 6-2.3: Errors indicated on LED...
  • Page 86 Ver. 2021‐09        Midea Building Technologies Division  Midea Group  Add.: Midea Headquarters Building, 6 Midea Avenue, Shunde, Foshan, Guangdong, China  Postal code: 528311  mbt.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. ...

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