Panasonic WH-UD07CE5-A Service Manual page 98

17.5.13. Outdoor High Pressure Protection (H98)
Malfunction Decision Conditions:
During operation of heating, when pressure 4.0 MPa and above is detected by outdoor high pressure sensor.
Malfunction Caused:
1. Faulty water pump.
2. Insufficient water flow rate in system.
3. Water leak in system.
4. 2/3 way closed.
5. Clogged expansion valve or strainer.
6. Excessive refrigerant.
7. Faulty outdoor high pressure sensor.
8. Faulty outdoor unit PCB (main).
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