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Is actual pressure detected by
pressure gage acceptable?
yes
no
low pressure failure
no
high pressure failure
yes
yes
Is high pressure too low?
no
is pipe blocked?
yes
Refrigerant charge is
needed. Check if there is
refrigerant leak. If yes,
replace pipe.
yes
dredge piping
Change pressure
switch
no
Make them in
short circuit
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.
1) Pressure protection
Confirm the fault according
to the fault code list
Does system have
pressure switch?
Are CN17 and CN18
in PCB cut off?
no
Replace PCB
yes
yes
no
no
no
yes
yes
yes
yes
Replace PCB
Is DC voltage between
both ends of sensor
near 5V or 0V?
Replace sensor
Is sensor resistance
acceptable?
Replace senso
r
Is sensor short-circuit
or open-circuit?
check if the wiring is
correct according to
wiring diagram
2) Sensor failure
no
reconnect
Relocate
if sensor is fixed
well
9.3 Troubleshooting for fixed frequency units
Re
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