Multi Plus ODU Main Board Troubleshooting

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Fault Code Fault Description Possible Reason for Fault Potential Fixes
1 Outdoor Ambient Temperature Sensor Fault
  • The outdoor ambient temperature sensor connection is loose
  • The outdoor ambient temperature sensor has failed
  • The sampling circuit has failed
  • Reconnect the outdoor ambient temperature sensor
  • Replace the outdoor ambient temperature sensor
  • Replace the outdoor board
2 Outdoor Coil Temperature Sensor Fault
  • The outdoor coil temperature sensor connection is loose
  • The outdoor coil temperature sensor has failed
  • The sampling circuit has failed
  • Reconnect the outdoor coil temperature sensor
  • Replace the outdoor coil temperature sensor
  • Replace the outdoor board
3 The Unit Over-Current Turn Off Fault
  • Control board current sampling circuit has failed
  • The current is too high because the supply voltage is too low
  • The compressor is blocked
  • Overload in heating mode
  • Overload in cooling mode
  • Replace the control board
  • Replace the compressor
4 EEprom Data Error
  • EE components have failed
  • EE components control circuit failed
  • EE components have been inserted incorrectly
  • Replace the EE components
  • Replace the outdoor control board
  • Reassemble the EE components
5 Cooling Freezing

Protection (the indoor coil temperature is too low) or Heating Overload (indoor coil temperature is too high)

  • The indoor unit isn't blowing air normally
  • The room temperature is too low in cooling mode or the room temperature is too high in heating
  • Air filter is dirty
  • The duct resistance is too high to result in low air flow
  • The setting fan speed is too low
  • The indoor unit is not standard installed, air inlet is too near with air outlet
  • Check the indoor fan, indoor fan motor and evaporator
  • Clean the filter
  • Check the volume control valve, duct length etc.
  • Set the speed with high speed
  • Reinstall the indoor unit refer to the user manual to change the distance between the indoor unit and the wall or ceiling.
7 Communication fault between the indoor unit and outdoor unit
  • The connection between the indoor unit and

outdoor unit is poor

  • The communication cable is loose
  • The communication cable is faulty
  • The indoor control board is faulty
  • The outdoor control board is faulty
  • Communication circuit fuse is open
  • The specification of communication cable is incorrect
  • Reconnect the connection cable by referring to the wiring diagram
  • Reconnect the communication cable
  • Replace the communication cable
  • Replace the indoor control board
  • Replace the outdoor control board
  • Check the communication circuit, adjust the DIP switch and the short-circuit fuse
  • Choose suitable communication cable by referring to the user manual
13 Compressor overheat protector device
  • The wiring of the overload protector connection is loose
  • The overload protector has failed
  • Insufficient refrigerant
  • The copper pipping is longer than normal, but no additional refrigerant has been added
  • The expansion valve has failed
  • The outdoor control board has failed
  • Reconnect the wiring of the

overload protector

  • Replace the overload

protector

  • Check for a refrigerant leak, fix it and re-add refrigerant
  • If there is no leak, add refrigerant according to the length of the copper tubing.
  • Replace expansion valve
  • Replace the outdoor control

board

14 The high pressure switch operates or the unit turns off for high pressure protection
  • The wiring of the high pressure protector connection is loose;
  • The high pressure protector has failed
  • The outdoor control board is abnormal
  • Overload in cooling
  • Overload in heating
  • Reconnect the high pressure protector
  • Replace the high pressure protector
  • Replace the outdoor control board
  • Refer to "Overload in Cooling Mode addendum"
  • Refer to "Overload in Heating Mode addendum"
15 Low pressure switch protection or the unit turned off for low pressure protection
  • The wiring of the low pressure switch is loose
  • The low pressure switch has failed
  • Insufficient amount of refrigerant
  • Expansion valve failure in heating mode
  • The outdoor control board is abnormal
  • Reconnect the wiring of the low pressure switch
  • Replace the low pressure switch
  • Check for a refrigerant leak, fix it and re-add refrigerant
  • Replace the expansion valve;
  • Replace the outdoor control

board

16 Overload protection in cooling mode System Overload Refer to "Overload in Cooling Mode addendum"
17 Discharge temperature sensor fault
  • The wiring of the discharge temperature sensor connection is loose
  • The discharge temperature sensor has failed
  • The sampling circuit is abnormal
  • Reconnect the discharge temperature sensor
  • Replace the discharge temperature sensor
  • Replace the outdoor control board.
18 AC voltage is abnormal
  • The AC voltage > 275V or < 160V
  • The AC voltage of sampling circuit on the driver board is abnormal
  • Please check the power supply
  • Replace the driver board
19 Suction temperature sensor fault
  • The wiring of the suction temperature sensor connection is loose
  • The suction temperature sensor has failed
  • The sampling circuit is abnormal
  • Reconnect the suction temperature sensor
  • Replace the suction temperature sensor
  • Replace the outdoor control board
22 Defrosting sensor fault
  • The wiring of the defrosting sensor connection is loose
  • The defrosting sensor has failed
  • The sampling circuit is abnormal
  • Reconnect the defrosting sensor
  • Replace the defrosting sensor
  • Replace the outdoor control board
23 Expansion valve A tube (thin) sensor fault
  • The wiring of the sensor for the expansion valve A(thin tube) connection is loose
  • The sensor for the expansion A(thin tube) has failed
  • The sampling circuit is abnormal
  • Reconnect the sensor for the expansion valve A (thin tube)
  • Replace the sensor for the expansion valve A (thin tube)
  • Replace the outdoor control board
24 Expansion valve B tube (thin) sensor fault
  • The wiring of the sensor for the expansion valve B(thin tube) connection is loose
  • The sensor for the expansion B(thin tube) has failed
  • The sampling circuit is abnormal
  • Reconnect the sensor for the expansion valve B (thin tube)
  • Replace the sensor for the expansion valve B (thin tube)
  • Replace the outdoor control board
25 Expansion valve C tube (thin) sensor fault
  • The wiring of the sensor for the expansion valve C(thin tube) connection is loose
  • The sensor for the expansion C(thin tube) has failed
  • The sampling circuit is abnormal
  • Reconnect the sensor for the expansion valve C (thin tube)
  • Replace the sensor for the expansion valve C (thin tube)
  • Replace the outdoor control board
26 Expansion valve D tube (thin) sensor fault
  • The wiring of the sensor for the expansion valve D(thin tube) connection is loose
  • The sensor for the expansion D(thin tube) has failed
  • The sampling circuit is abnormal
  • Reconnect the sensor for the expansion valve D (thin tube)
  • Replace the sensor for the expansion valve D (thin tube)
  • Replace the outdoor control board
27 Expansion valve A tube (thick) sensor fault
  • The wiring of the sensor for the expansion valve A(thick tube) connection is loose
  • The sensor for the expansion A(thick tube) has failed
  • The sampling circuit is abnormal
  • Reconnect the sensor for the expansion valve A (thick tube)
  • Replace the sensor for the expansion valve A (thick tube)
  • Replace the outdoor control board
28 Expansion valve B tube (thick) sensor fault
  • The wiring of the sensor for the expansion valve B(thick tube) connection is loose
  • The sensor for the expansion B(thick tube) has failed
  • The sampling circuit is abnormal
  • Reconnect the sensor for the expansion valve B (thick tube)
  • Replace the sensor for the expansion valve B (thick tube)
  • Replace the outdoor control board
29 Expansion valve C tube (thick) sensor fault
  • The wiring of the sensor for the expansion valve C(thick tube) connection is loose
  • The sensor for the expansion C(thick tube) has failed
  • The sampling circuit is abnormal
  • Reconnect the sensor for the expansion valve C (thick tube)
  • Replace the sensor for the expansion valve C (thick tube)
  • Replace the outdoor control board
30 Expansion valve D tube (thick) sensor fault
  • The wiring of the sensor for the expansion valve D(thick tube) connection is loose
  • The sensor for the expansion D(thick tube) has failed
  • The sampling circuit is abnormal
  • Reconnect the sensor for the expansion valve D (thick tube)
  • Replace the sensor for the expansion valve D (thick tube)
  • Replace the outdoor control board
45 IPM fault Please refer to "drive board fault codes" for more information Please refer to "drive board fault codes" for more information
46 IPM and control board communication fault
  • The cable between the control board and the driver board is loose
  • The cable between the control board and the driver board has failed
  • The driver board has failed
  • The control board has failed
  • Reconnect the cable between the control board and the driver board
  • Replace the communication cable between the control board and the driver board
  • Replace the driver board
  • Replace the control board
47 Discharge temperature too high fault
  • Insufficient amount of refrigerant
  • The refrigerant of the unit is not enough due to additional length of the installation pipe
  • Throttling service has failed
  • The outdoor ambient temperature is too high
  • Check for refrigerant leaks. Fix leak and re-add refrigerant
  • Add refrigerant according to additional installation pipe length
  • Replace the throttling service (such as capillary, expansion valve)
48 Outdoor DC fan motor fault (upper fan motor)
  • The wiring of the upper DC fan motor is loose
  • The cord of the upper DC fan motor has failed
  • The upper DC fan motor has failed
  • The drive circuit of the upper DC fan motor has failed
  • The outdoor fan has been blocked
  • Reconnect the wiring of the upper DC fan motor
  • Replace the upper DC fan motor
  • Replace the driver board of the fan motor
  • Check the outdoor fan and ensure the outdoor fan can run normally
49 Outdoor DC fan motor fault (lower fan motor)
  • The wiring of the lower DC fan motor is loose
  • The cord of the lower DC fan motor has failed
  • The lower DC fan motor has failed
  • The drive circuit of the lower DC fan motor has failed
  • The outdoor fan has been blocked
  • Reconnect the wiring of the lower DC fan motor
  • Replace the lower DC fan motor
  • Replace the driver board of the fan motor
  • Check the outdoor fan and ensure the outdoor fan can run normally
91 The unit turned off due to the IPM board over heating fault
  • The outdoor ambient temperature is too high
  • The speed of the outdoor fan motor is too low
  • The outdoor unit has been installed incorrectly
  • The supply power is too low
  • Check the fan capacitor, and replace the fan capacitor if it has failed
  • Reinstall the outdoor unit by referring to the installation user manual
96 The refrigerant of the unit is not enough fault Insufficient amount of refrigerant
  • Check for leaks
  • Charge refrigerant to recommended levels
97 4-way valve communication failure fault
  • The wiring of the 4-way valve coil is loose
  • The 4-way valve coil has failed
  • The 4-way valve has failed
  • The driver board of the 4-way valve has failed
  • Reconnect the wiring of the 4-way valve
  • Replace the 4-way valve coil
  • Replace the 4-way valve
  • Replace the driver board of the 4-way valve
Overload in Cooling Mode Addendum
Number Cause Corrective Measures
1 Too much refrigerant Discharge refrigerant and refill to the appropriate level
2 The outdoor ambient temperature is too high Please use within the rated ambient temperature range
3 The air outlet and the air inlet of the outdoor unit has short circuited Adjust the installation according to the installation manual
4 The outdoor heat exchanger is dirty Clean the heat exchanger of the outdoor unit
5 The speed of the outdoor fan motor is too low Check the outdoor fan motor or fan capacitor
6 The outdoor fan is broken or the outdoor fan is blocked Check the outdoor fan
7 The air inlet and outlet and been blocked Remove the blockage
8 The expansion valve or the capillary has failed Replace the expansion valve or the capillary
Overload in Heating Mode Addendum
Number Cause Corrective Measures
1 Too much refrigerant Discharge refrigerant and refill to the appropriate level
2 The indoor ambient temperature is too high Please use within the rated ambient temperature range
3 The air outlet and the air inlet of the indoor unit has short circuited Adjust the installation according to the installation manual
4 The indoor filter is dirty Clean the indoor filter
5 The speed of the indoor fan motor is too low Check the indoor fan motor or fan capacitor
6 The indoor fan is broken or the outdoor fan is blocked Check the indoor fan
7 The air inlet and outlet and been blocked Remove the blockage
8 The expansion valve or the capillary has failed Replace the expansion valve or the capillary

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