Panasonic WH-UD30BE5-1 Service Manual page 61

16.5.18. Four Way Valve Abnormality (F25)
Malfunction Decision Conditions:
During operation of heating, when temperature below 0°C is detected by indoor pipe temperature sensor.
Malfunction Caused:
1. Faulty sensor.
2. Faulty connector connection.
3. Faulty outdoor unit PCB.
4. Faulty four way valve.
Abnormality Judgment:
Continue 4 times in 30 minutes.
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