SiSG121917E
Troubleshooting for Outdoor Unit
Part 6 Service Diagnosis
138
7. Troubleshooting for Outdoor Unit
7.1 Refrigerant Shortage
Error Code
U0
Outdoor Unit LED
Display
A
j
1
h
2
h
3
i
4
i
5
h
Method of Error
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 lower than the normal value.
Error Decision
Conditions
Refrigerant shortage detection:
The following conditions continue for 7 minutes.
Input current
A
× output fre
B
Output frequency >
C
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 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
(coefficient)
B
(A)
C
(Hz)
50/65/80 class
10/1000
0.3
54
90 class
27/1000
2
40
