45
Installation and Maintenance
Service Manual
(3) High temperature and overload protection diagnosis (AP1 hereinafter refers to the control board of the 
outdoor unit)
Mainly detect:
●Is outdoor ambient temperature in normal range?
●Are the outdoor and indoor fans operating normally?
●Is the heat dissipation environment inside and outside the unit good?
Fault diagnosis process:
End
Yes
No
Yes
No
Yes
No
Overheat and high 
temperature protection
Is outdoor ambient temperature higher than 53?
20 minutes after the complete 
unit is powered off.
Is heat dissipation of the indoor unit 
and outdoor unit abnormal?
Normal protection, please operate 
it after the outdoor ambient temp-
erature is normalized.
Improve the heat 
dissipation environ-
ment of the unit
Does the outdoor fan work normally?
1. Check if the fan terminal OFAN 
is connected correctly
2. Resistance between any two 
terminals is measure by an ohm 
gauge and should be less than 1K 
Ohm.
Replace the  
control panel 
AP1
Replace the fan 
capacitor C1
Replace the 
outdoor fan