Refrigerant Shortage - Daikin FTXG20LV1BW Service Manual

Troubleshooting
4.7

Refrigerant Shortage

U0
Error Code
Method of Error Refrigerant shortage detection I:
Refrigerant shortage is detected by checking the input current value and the compressor
Detection
running frequency. If the refrigerant is short, the input current is lower 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.
Refrigerant shortage detection III: (20/25/35 class only)
Refrigerant shortage is detected by checking the difference between suction and discharge
temperature.
Error Decision Refrigerant shortage detection I:
The following conditions continue for 7 minutes.
Conditions
20/25/35 class
50 class
Refrigerant shortage detection II:
The following conditions continue for 80 seconds.
20/25/35 class
50 class
Refrigerant shortage detection III: (20/25/35 class only)
When the difference of the temperature is smaller than G°C, it is regarded as refrigerant
shortage.
Operation
mode
Cooling
Heating
Supposed
Causes
65
Input current × input voltage
Output frequency > C
A
(constant)
640/256
2000/256
Opening of the electronic expansion valve ≥ D
Discharge pipe temperature > E × target discharge pipe temperature + F
D (pulse)
480
480
Description
room thermistor temperature – indoor heat exchanger temperature
outdoor heat exchanger temperature – outdoor temperature
indoor heat exchanger temperature – room thermistor temperature
outdoor temperature – outdoor heat exchanger temperature
If the error repeats, the system is shut down.
Reset condition: Continuous run for about 60 minutes without any other error
Disconnection of the discharge pipe thermistor, indoor or outdoor heat exchanger thermistor,
room or outdoor temperature thermistor
Closed stop valve
Refrigerant shortage (refrigerant leakage)
Poor compression performance of compressor
Defective electronic expansion valve
≤
A × output frequency + B
B (W) C (Hz)
0
–181
E ( )
constant
128/128
128/128 cooling: 60, heating: 45
SiBE041401E
55
55
F (°C)
30
G (°C)
4.0
4.0
3.0
3.0
Service Diagnosis