Low pressure protection 
Low pressure protection 
Whether  the wiring 
between the low pressure 
protector and main control 
board is connected well or 
correctly
Whether  the wiring 
between the low pressure 
protector and main control 
board is connected well or 
correctly
Method: Disconnect the plug. 
Measure the resistance of the 
low pressure protector. If the 
protector is normal the value is 
o
Method: Disconnect the plug. 
Measure the resistance of the 
low pressure protector. If the 
protector is normal the value is 
o
Yes
Yes
Connect it well
Connect it well
Replace outdoor main board
Replace outdoor main board
No
Replace low pressure protector
Replace low pressure protector
No
Whether the low 
pressure protector 
is broken
Whether the low 
pressure protector 
is broken
Check whether the outdoor 
ambient temperature is too 
low
Check whether the outdoor 
ambient temperature is too 
low
No
Stop the unit 
Stop the unit Yes
Open fully valve core of 
high pressure valve
Open fully valve core of 
high pressure valve
No
Check whether valve core 
of high pressure valve is 
opened
Check whether valve core 
of high pressure valve is 
opened
Check if the indoor fan runs 
properly in cooling mode
Check if the indoor fan runs 
properly in cooling mode
please refer to the solution of fan 
speed has been out of control 
malfunction. Find out the cause and 
have it solved.
please refer to the solution of fan 
speed has been out of control 
malfunction. Find out the cause and 
have it solved.
No
Yes
Yes
No
Check whether the refrigerant 
system is ok
Check whether the refrigerant 
system is ok
Refrigerant is not enough add the 
refrigerant
Refrigerant is not enough add the 
refrigerant
No