Panasonic CS-RE18NKE Service Manual page 64

15.5.14 F11 (4-way valve Abnormality)
Malfunction Decision Conditions
When heating operation, when indoor pipe temperature is below 10°C.
When cooling operation, when indoor pipe temperature is above 45°C.
Malfunction Caused
Connector in poor contact.
Faulty sensor.
Faulty outdoor unit PCB.
4-way valve defective.
Troubleshooting
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