Panasonic WH-UD30BE5-1 Service Manual page 53

16.5.10. Outdoor High Pressure Switch Activate (F12)
Malfunction Decision Conditions:
During operation of heating, when pressure 4.5 MPa and above is detected by outdoor high pressure switch.
Malfunction Caused:
1. Faulty water pump.
2. Insufficient water flow rate in system.
3. Water leak in system.
4. Clogged expansion valve or strainer.
5. Excessive refrigerant.
6. Faulty outdoor high pressure sensor and switch.
7. Faulty outdoor unit PCB.
Abnormality Judgment:
Continue 4 times in 20 minutes.
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