Daikin FTXN24KVJU Service Manual

Troubleshooting SiUS041111
112 Service Diagnosis
4.23 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 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:
Refrigerant shortage is detected by checking the difference between suction and discharge
temperature.
Malfunction
Decision
Conditions
Refrigerant shortage detection I:
The following conditions continue for 7 minutes.
 Input current × input voltage
 A × output frequency + B
 Output frequency > C
Refrigerant shortage detection II:
The following conditions continue for 80 seconds.
 Opening of the electronic expansion valve  D
 Discharge pipe temperature (°C) > E × target discharge pipe temperature (°C) + F (°C)
(Discharge pipe temperature (°F) > E × target discharge pipe temperature (°F) + G (°F))
Refrigerant shortage detection III: (15/18/24 class only)
When the difference of the temperature is smaller than H, it is regarded as refrigerant shortage.
 If the error repeats, the system is shut down.
 Reset condition: Continuous run for about 60 minutes without any other error
Supposed
Causes
 Disconnection of 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
(–) B (W) C (Hz)
09/12 class 777/256 –15 50
15/18/24 class 2000/256 –181 54
D (pulse) E (–) F (°C) G (°F)
09/12 class
Cooling
470
160/128 –1.5 –10.7
Heating 172/128 –8.0 –25.4
15/18/24 class 470 128/128 20 36
H
Cooling
room thermistor temperature – indoor heat exchanger temperature 4.0°C (7.2°F)
outdoor heat exchanger temperature – outdoor temperature 4.0°C (7.2°F)
Heating
indoor heat exchanger temperature – room thermistor temperature 4.0°C (7.2°F)
outdoor temperature – outdoor heat exchanger temperature 4.0°C (7.2°F)

Daikin FTXN24KVJU Specifications

General

Brand	Daikin
Model	FTXN24KVJU
Category	Air Conditioner
Language	English