Check if the air flow system 
of indoor and outdoor units 
are obstructed?
Clear up the air inlet and outlet or the heat 
exchanger of indoor and outdoor units.
Yes
No
Yes
Yes
Turn off the power supply and turn 
it on 10 minutes later.
Check if the unit can start 
normally.
No
Check if the refrigerant 
charge volume is normal?
Recharge the correct 
refrigerant volume.
Refrigerant system is blocked, such 
as capillary or welded point of pipes.
Yes
Check if all the connection, especially 
the connection of OLP (Over Load 
Protector) sensor is good.
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
No