Panasonic CU-4E24RBU - Page 72

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15.2.17 F91 (Refrigeration Cycle Abnormality)
Malfunction Decision Conditions
 Gas shortage detection I: 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 II: A gas shortage is detected by checking the difference between indoor pipe
temperature and indoor intake air temperature during cooling and heating.
Malfunction Caused
 Refrigerant shortage (refrigerant leakage).
 Poor compression performance of compressor.
 2/3 way valve closed.
 Detection error due to faulty indoor intake air and indoor pipe temperature sensors.
Abnormality Judgment:
 4 times happen within 60 minutes.
Troubleshooting
For safety reason and to prevent component
breakdown, always switch off the power before
remove and connect the component.
2/3 way valve closed?
No
Check the indoor intake air and
indoor pipe temperature sensors.
Replace the indoor intake air or
indoor pipe temperature sensor.
No
Does it conform to the
sensor characteristic chart?
Yes
Replace the capillary
tube or dryer.
Capillary tube or dryer
clogged?
Repair the pipe flare or
union nuts. Reclaim and
recharge refrigerant.
Yes
Charge for a specified
amount of fresh refrigerant.
- Replace outdoor unit PCB
- Compressor
Yes
No
No
No
Open the 2/3 way valve.
Yes
Check for gas leakage.
Oil oozing out from the
2/3 way valve?
Yes
Refrigeration cycle
abnormality error again?
Procedure complete.