Panasonic CS-YS9MKV-7 Service Manual page 75

14.4.15 F91 (Refrigeration Cycle Abnormality)
Malfunction Decision Conditions

During cooling, compressor frequency = Fcmax.

During cooling and heating operation, running current: 0.65A < I < 1.65A.

During cooling, indoor intake - indoor pipe < 4°C.
Malfunction Caused

Refrigerant shortage (refrigerant leakage)

Poor compression performance of compressor.

2/3 way valve closed.

Detection error due to faulty indoor intake air or indoor pipe temperature sensors.
Troubleshooting
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