SiUS091133
Troubleshooting
Service Diagnosis
104
4.6
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.
<09/12 class>
Input current × input voltage
A × output fre B
Output frequency > C
<15/18/24/30/36 class>
Input current
D × output fre E
Output frequency > F
Refrigerant shortage detection II:
The following conditions continue for 80 seconds.
Opening of the electronic expansion valve
G
Discharge pipe temperature (°C) > H × target discharge pipe temperature (°C) + J (°C)
(Discharge pipe temperature (°F) > H × target discharge pipe temperature (°F) + K (°F))
A
(–)
B (W)
C (Hz)
09/12 class
640/256
0
55
D
(–)
E
(A)
F
(Hz)
15/18 class
2000/256
–181
55
24/30/36 class
27/1000
2.0
40
G (pulse)
H (–)
J (°C)
K (°F)
09/12 class
480
128/128
cooling: 63.5, heating: 30 cooling: 114.3, heating: 54
15/18 class
480
128/128
cooling: 60, heating: 45
cooling: 108, heating: 81
24 class
450
128/128
60
108
30/36 class
480
128/128
cooling: 50, heating: 45
cooling: 90, heating: 81
