Panasonic WH-UD28AE Service Manual page 55

16.5.13. Indoor-Control Panel Communication Abnormality (H65)
Malfunction Decision Conditions:
During standby and operation of heating, indoor-control panel error occur.
Malfunction Caused:
1. Faulty connector connection.
2. Faulty control panel.
3. Faulty PCB.
Abnormality Judgment:
Continue for 1 minute.
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