51
Installation and Maintenance
Service Manual
4.Diagnosis for failure start up malfunction (AP1 below is control board of outdoor unit)
Main detection point:
● If the compressor wiring is correct?
● If the stop time of compressor is enough?
● If the compressor is damaged?
● If the refrigerant charging is too much?
Malfunction diagnosis process:
Energize the unit 
and start it
If the compressor wire  COMP(UVW) is 
well connected and connection sequence
is correct
Replace control board AP1
Replace the 
compressor
If malfunction is 
removed?
If the stop time of compressor 
is more than 3min?
N
If the stop time is not enough and the 
high and low pressure of system is not 
balance , please start it after 3min
Improve the connection situation 
of control board AP1 and 
compressor COMP, connect it 
with wiring diagram
N
Y
N
If the refrigerant charging is 
too much?
Y
Does the unit start 
up normally? 
N
Charge the 
refrigerant according
to service manual
Y
Does the unit start 
up normally? 
N
Y
End