Panasonic WH-MXC09J3E5 Service Manual page 193

18.5.27 Outdoor High Pressure Switch Activate (F12)
Malfunction Decision Conditions:
During operation of cooling and heating, when pressure 4.3 MPa and above is detected by outdoor high pressure
switch.
Malfunction Caused:
1 Dust accumulation on the outdoor unit heat exchanger.
2 Air short circuit at outdoor unit.
3 Faulty water pump.
4 Insufficient water flow rate in system.
5 Water leak in system.
6 2/3 way valve closed.
7 Clogged expansion valve or strainer.
8 Excessive refrigerant.
9 Faulty outdoor high pressure sensor and switch.
10 Faulty outdoor unit PCB.
Abnormality Judgment:
Continue 4 times in 30 minutes.
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