Panasonic WH-UD28AE Service Manual page 64

16.5.22. Compressor Overheating (F97)
Malfunction Decision Conditions:
During operation of heating, temperature above 112°C is detected by the compressor tank temperature sensor.
Malfunction Caused:
1. Refrigerant shortage (refrigerant leakage).
2. 2/3 way valve closed.
3. Detection error due to faulty compressor tank temperature sensor.
Abnormality Judgment:
Continue 4 times in 30 minutes.
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