Panasonic CS-E7NKDW Service Manual page 97

16.4.23 F91 (Refrigeration Cycle Abnormality)
Malfunction Decision Conditions
During cooling, compressor frequency = Fcmax.
During heating, compressor frequency > Fhrated.
During cooling and heating operation, running current: 0.65A < I < 1.65A.
During cooling, indoor intake - indoor pipe < 4°C
During heating, indoor pipe - indoor intake < 5°C
Multi Models Only
Gas shortage detection 1: A gas shortage is detected by checking the CT-detected input current value
and the compressor running frequency. During startup and operating of cooling and heating, input
current < 8.78/256 (A/Hz) x compressor running frequency + 0.25.
Gas shortage detection 2: A gas shortage is detected by checking the difference between indoor pipe
temperature and indoor intake air temperature during cooling and heating.
Malfunction Caused
Faulty indoor intake air or pipe temperature sensor
2/3 way valve closed
Refrigerant shortage (refrigerant leakage)
Clogged expansion valve or strainer
Faulty outdoor unit
Poor compression of compressor
Troubleshooting
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