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

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