39
6. Diagnosis for compressor synchronism (AP1 below is control board of the outdoor unit)
Main detection points:
S Is the system pressure high?
S Is the voltage too low?
Malfunction diagnosis process:
If the compressor wire COMP(UVW) is well 
connected, the connection sequence
forwards to clockwise direction?
Check if the fan 
terminal OFAN is 
connected well
Replace 
compressor
If the outdoor fan works 
normally?
If the stop time of 
compressor is more than 
3min
Synchronism after
energize the unit 
and start it
Connect
wire well
Synchronism
occurred during 
operation
Replace 
control board 
AP1
If the radiating of unit is 
well?
Remove
malfunction?
Improve the radiating 
of unit (clean heat 
exchanger and 
increase ventilation)
Replace fan 
capacitor C1
Replace
outdoor fan
Yes
No
No
No
Yes
Yes
No
Replace 
control board 
AP1
Remove
malfunction?
Replace 
compressor
Yes
No
No
Yes
If the input voltage of unit 
is normal?
Start to run until the 
power resume normal 
voltage
N
If the refrigerant is too 
much?
Charge the 
refrigerant with 
service manual
Yes
Yes
No
Yes
End
End
No
Fig. 42 – Troubleshooting