184
DC Inverter Multi 
VRF Service Manual
3) Solution to the DC Bus High Voltage Protection
It is finished
DC Bus High Voltage Protection
Check if the input voltage is 
larger than 460V?
Replace the compressor drive 
board
Adjust the voltage to 380V and 
then see if the error is 
eliminated
YES
NO
NO
4) Solution to DC Bus Low Voltage Protection
It is finished
DC Bus Low Voltage Protection
Check if the input voltage is 
lower than 320V?
Replace the compressor drive 
board
Adjust the voltage to 380V and 
then see if the error is 
eliminated?
YES
NO
NO
Note: For both the compressor and fan motor drive boards, the solution to DC bus low/high voltage protection is the 
same.
5) Solution to the Open Phase Protection
It is finished
Open Phase
Check if the power cord
 of the compressor is  connected 
properly
Replace the compressor drive 
board
Connect the power cord 
properly and see if the error is 
eliminated
NO
YES
NO