Haier AB422XCBAA Service Manual page 163

6) External alarm
An external alarm is
identified according to the
list of fault codes
Is an external alarm
connected to the system?
no
Is ALARM terminal in
mainboard disconnected?
yes
Short connect that
terminal
yes
if failure disappear after
PCB is changed
no
replace PCB
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.
Note: The confirmation time of low pressure failure may be shorter, but
high pressure failure confirmation time is at least 1 hour. Besides, take
the ambient temperature into consideration.
yes
Solve problem
accordingly
no
Are ports 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
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