Panasonic WH-ADC0916G9E8 WH-UX09FE8 Service Manual page 114

17.5.6 Compressor Low Pressure Protection (H42)
Malfunction Decision Conditions:
During operation of heating and after 5 minutes compressor ON, when outdoor pipe temperature below -29°C or
above 26°C is detected by the outdoor pipe temperature sensor.
Malfunction Caused:
1 Dust accumulation on the outdoor unit heat exchanger.
2 Air short circuit at outdoor unit.
3 2 way valve partially closed.
4 Faulty outdoor unit fan motor.
5 Refrigerant shortage (refrigerant leakage).
6 Clogged expansion valve or strainer.
7 Faulty outdoor pipe temperature sensor.
8 Faulty outdoor unit main PCB (main).
Troubleshooting:
Check the dust accumulation on the
outdoor unit heat exchanger.
Is the outdoor unit heat
exchanger dirty?
No
Check the outdoor air
passage.
Is there any short circuit?
No
Check the 2-way valve.
Is the 2 way valve partially
closed?
No
For safety reason and to prevent component breakdown,
always switch off the power before remove and connect the component.
Yes
Clean the heat exchanger.
Yes
Provide sufficient air
passage.
Yes
Open the 2 way valve.
Check the outdoor unit
fan motor operation.
Is the outdoor unit fan
motor operate normally?
Yes
Check for gas leakage.
Is the oil oozing out from
the 2/3 way valve?
No
Check for clogged
expansion valve or stainer.
Is the expansion valve or
strainer clogged (ice formed)?
No
Reclaim and recharge for a
specified amount of fresh refrigerant.
Is abnormality happened
again?
No
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Replace the outdoor unit
No
fan motor and/or outdoor
unit PCB (main).
- Repair the pipe flare or
Yes
union nuts.
- Reclaim and recharge
refrigerant.
- Replace the expansion
Yes
valve and/or strainer.
- Reclaim and recharge
refrigerant.
- Replace the outdoor unit
PCB (main).
Yes
- Replace the outdoor pipe
temperature sensor.
- Replace the compressor.
Procedure complete