
10 Troubleshooting
Troubleshooting procedure
SMGB0091 rev.2 - 11/2015
217
10
Alarm code
08
Excessively high discharge gas temperature at the top of compressor
• The alarm appears during cooling operation when the compressor-top thermistor temperature remains at Tdc1 or
above for 10 minutes, or at Tdc2 or above for 5 seconds.
• The alarm appears during heating operation when the compressor-top thermistor temperature remains at Tdh1 or
above for 10 minutes, or at Tdh2 or above for 5 seconds.
Compressor-top thermistor
(THM9)
Is the thermistor THM9 on top of
compressor normal?
Faulty thermistor
No
Yes
Is the thermistor THM9 installed
correctly on the compressor?
Install it correctly
No
Yes
Correctly charge refrigerant
Yes
Is gas leaking?
Repair leaks of gas.
Correctly charge refrigerant.
No
1072,0
640,4
394,2
249,2
161,5
107,0 72,3
50,0 35,1 25,1 18,2 13,4 9,9 7,5
6,5
0
200
400
600
800
1000
1200
-10 0
10 20 30 40 50 60 70 80 90 100 110 120 130
Thermistor resistance characteristics
Temperature (ºC)
Thermistor resistance (kΩ)
Limits of temperature
A thermistor for the upper part temperature of the compressor is installed to prevent discharge gas from overheating.
If discharge gas temperature increases excessively lubricating oil deterioration occurs and lubricating properties
deteriorate, resulting in short compressor life.
When the upper part temperature of compressor increases during operation, the solenoid valve SVA of the unit is opened
to return the refrigerant to the compressor (through the accumulator for RASC unit).
If discharge gas temperature increases excessively, compressor temperature increases. At the worst, compressor
motor winding can be burnt out. In this case, the protection control is activated and the compressor is stopped if the
temperature values are higher than the following values:
RASC unit capacity
Cooling operation
Heating operation
Tdc1
Tdc2
Tdh1
Tdh2
RASC-(4-6)HNPE
115
125
115
125
RASC-(8/10)HNPE
127
135
120
135