Haier HPU-42CV03 Service Manual page 53

7) Pressure protection
Confirm the fault according
to the fault code list
Does system have
pressure switch?
yes
Is actual pressure detected by
pressure gage acceptable?
no
low pressure failure
yes
Is high pressure too low?
yes
Refrigerant charge is
needed. Check if there is
refrigerant leak. If yes,
replace pipe.
Commercial Air Conditioner
no
Are CN17 and CN18
in PCB cut off?
yes
Make them in
short circuit
yes
Change pressure
switch
no
high pressure failure
yes
no
is pipe blocked?
yes
dredge piping
no
Replace PCB
52
Model: HPU-42CV03
HPU-42HV03