Troubleshooting For Outdoor Unit; Refrigerant Shortage - Daikin Super multi NX E Series Service Manual

SiBE121135_A

7. Troubleshooting for Outdoor Unit

7.1

Refrigerant Shortage

U0
Error Code
Outdoor Unit LED
A
∗ LED5 is equipped only on the 5-room model.
Display
Method of Error
Refrigerant shortage detection I :
Detection Refrigerant shortage is detected by checking the input current value and the compressor output
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 outdoor electronic expansion valve. If the refrigerant is short, the discharge pipe
temperature tends to rise.
Error Decision Refrigerant shortage detection I :
Conditions The following conditions continue for 7 minutes.
40/50/52/58 class
68/75 class
80/90 class
Refrigerant shortage detection II :
The following conditions continue for 80 seconds.
Supposed
Causes
Service Diagnosis
j h h i i
1 2 3 4
≤
DC current A × Compressor output frequency + B
Output frequency > C
A (–)
0.01
0.035
0.027
Opening of the outdoor electronic expansion valve ≥ D
Discharge pipe temperature > E × target discharge pipe temperature + F
D (pulse)
Cooling
450
Heating
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 outdoor electronic expansion valve
h
5
B (A) C (Hz)
0.3 54
0.5 55
2.0 40
E (–) F (°C)
20
255/256
40

Troubleshooting for Outdoor Unit

200