Panasonic WH-SDF09C3E5 Service Manual page 119

17.5.24 Four Way Valve Abnormality (F25)
Malfunction Decision Conditions:
During heating operation, when the indoor pipe temperature of thermostat ON indoor unit < 0°C.
Malfunction Caused:
1 Faulty sensor.
2 Faulty connector connection.
3 Faulty outdoor unit PCB (noise filter/main).
4 Faulty four way valve.
Abnormality Judgment:
Continue 4 times in 30 minutes.
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