Check the air flow system 
of indoor and outdoor units 
Clear up the air inlet and outlet or the heat 
exchanger of indoor and outdoor units.
Yes
No
Yes
Yes
Power off, then restart the unit 10 
minutes later
Check if the temperature 
of compressor 
No
Check refrigerant system
Yes
Check the overload 
protector
Correct the connection.No
Measure the resistance 
between the two ports of 
the OLP. Is it zero?
Yes
Replace the OLP.
No
Replace the outdoor control PCB.
Yes