Multi Plus ODU Main Board Troubleshooting

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"