Daikin FTXS09HVJU Service Manual page 151

SiUS04-904
4.21.2 15/18/24 Class
U0
Remote
Controller
Display
Method of Refrigerant shortage detection I :
Refrigerant shortage is detected by checking the CT-detected input current value and the
Malfunction
compressor running frequency.
Detection
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.
Refrigerant shortage detection III:
Refrigerant shortage is detected by checking the difference between air suction and discharge
temperature.
Malfunction
Refrigerant shortage detection I :
Input current <
Decision
However, when the status of running frequency > 55 (Hz) is kept on for a certain time.
Conditions
Note : The values are different from model to model.
If refrigerant shortage error takes place 4 times successively, the system is shut down. The error
counter is reset if this or any other error does not occur during the following 60-minute compressor
running time (total time).
 Refrigerant shortage (refrigerant leakage)
Supposed
 Poor compression performance of compressor
Causes
 Discharge pipe thermistor disconnected, or indoor unit or outdoor unit heat exchanger
 Stop valve closed
 Electronic expansion valve defective
140
(A/Hz) x Compressor running frequency
1756 / 256 –50
thermistor disconnected, room or outside air temperature thermistor disconnected
Troubleshooting
Voltage +
Service Diagnosis