Panasonic WH-UD07CE5-A Service Manual page 100

17.5.15. Outdoor High Pressure Switch Activate (F12)
Malfunction Decision Conditions:
During operation of cooling and heating, when pressure 4.5MPa 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 20 minutes.
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