SiBE12-908
Troubleshooting
Service Diagnosis
154
2.31 Refrigerant Shortage
Remote
Controller Display
U0
Method of
Malfunction
Detection
Refrigerant shortage detection I:
Refrigerant shortage is detected by checking the input current value and the compressor
running frequency. If the refrigerant is short, the input current is smaller than the normal value.
Refrigerant shortage detection II:
Refrigerant shortage is detected by checking the discharge pipe temperature and the opening of
the electronic expansion valve. If the refrigerant is short, the discharge pipe temperature tends
to rise.
Malfunction
Decision
Conditions
Refrigerant shortage detection I:
40 class
The following conditions continue for 7 minutes.
Input current × input voltage
≤
2111 / 256 × output frequency – 361 (W)
Output frequency > 51 (Hz)
50 class
The following conditions continue for 7 minutes.
Input current × input voltage
≤
4628 / 256 × output frequency – 608 (W)
Output frequency > 48 (Hz)
Refrigerant shortage detection II:
The following conditions continue for 80 seconds.
Target opening of the electronic expansion valve
≥
450 (pulse)
Discharge pipe temperature > 128 / 128 × target discharge pipe tempe20 (°C)
If a refrigerant shortage error takes place 4 times successively, the system is shut down. The
error counter resets itself if this or any other error does not occur during the following 60-minute
compressor running time (total time).
Supposed
Causes
Refrigerant shortage (refrigerant leakage)
Refrigerant heat exchanger drift
Poor compression performance of compressor
Closed stop valve
Defective electronic expansion valve