40
7. Diagnosis for overboard and discharge malfunction (AP1 below is control board of outdoor unit)
Main detection points:
S Is the electron expansion valve well connected? Is the expansion valve damaged?
S Is there a refrigerant leak?
S Is the overload protection damaged?
Malfunction diagnosis process:
Connect wire 
wiring diagram
Replace EKV 
coil of electronic
expansion valve
If the wiring terminal FA  
is well connected?
Remove 
malfunction?
The resistance value of 
firs t 4 l e ad fo ot  an d th e 
fif th lead fo ot is similar,  
less than100
After the unit 
de-energized 
for 20min
Remove 
malfunction?
Yes
No
No
No
Is the overload protector SAT 
well connected?
No
Under ambient temperature, test the 
resistance of  overload protector  
Yes
Yes
Replace 
overload 
protector SAT
No
Yes
Check refrigerant, if there is 
leakage, please refer to unit
specification
Replace 
control board 
AP1
End
resistance value 1000  
Fig. 43 – Troubleshooting