Refrigerant Shortage - Daikin H Series Service Manual

Troubleshooting

4.23 Refrigerant Shortage

U0
Remote
Controller
Display
Method of
Refrigerant shortage detection I:
Malfunction 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.
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 suction and discharge
temperature.
Malfunction Refrigerant shortage detection I:
Decision The following conditions continue for 7 minutes.
Conditions
 Input current
 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)
Cooling
Heating
 If the error repeats, the system is shut down.
 Reset condition: Continuous run for about 60 minutes without any other error
 Disconnection of discharge pipe thermistor, indoor or outdoor heat exchanger thermistor, room
Supposed
Causes
 Closed stop valve
 Refrigerant shortage (refrigerant leakage)
 Poor compression performance of compressor
 Defective electronic expansion valve
Service Diagnosis

A × output frequency + B
A (–) B (A)
27/1000 2.0
(Discharge pipe temperature (°F) > E × target discharge pipe temperature (°F) + G (°F))
D (pulse)
480
or outdoor temperature thermistor
C (Hz)
40
E (–) F (°C)
128/128
SiUS04-924_A
G (°F)
50 90
45 81
105