58
Installation and Maintenance
Service Manual
8. Malfunction of Overcurrent Protection
Main detection points:
● Is the supply voltage unstable with big uctuation?
● Is the supply voltage too low with overload?
● Hardware trouble?
Malfunction diagnosis process:
Start
Is the supply voltage unstable
of the rated voltage on the nameplate
Adjust the supply voltage to maintain it 
within normal range
Check the motor and reinstall the 
motor to have the fan run normally
Clean the indoor and outdoor heat 
exchangers and remove the blockage 
of air inlet and outlet
Replace the mainboard with the same 
model
Replace the compressor
Flush the heat exchangers with high 
pressure nitrogen
End
Is the supply voltage too low
with overload?
Replace the mainboard 
with the same model
Is the indoor / outdoor
heat exchanger dirty,or are the air inlet
and outlet blocked?
The fan is abnormal? Fan
speed is too low or fan doesnt rotate
Measure the current of live wire on 
the main board with a clamp ampere 
meter. Is the current higher than the 
value of the overcurrent protection?
eliminated
Is malfunction 
Is there blockage inside the system? 
(Filth blockage, ice plug, greasy 
blockage, the cut off valve hasnt been 
opened completely)
eliminated
Is malfunction 
Is malfunction 
eliminated
Is the compressor running abnormally? 
Is there abnormal sound or oil leakage; 
Is the temperature of the shell too high, 
etc.?
Is malfunction 
eliminated
eliminated
Is malfunction 
Is malfunction 
eliminated
eliminated
Is malfunction 
Yes Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No No
No
No
No
No
No No
No
No
No
No
No