Fujitsu AR 18LUAD Series Service Instruction page 79

Trouble shooting 19
OUTDOOR UNIT Error Method:
Heat Sink Temperature Sensor Error
Detective Actuators:
Outdoor Unit Main PCB Circuit
Heat Sink Temperature Thermistor
Forecast of Cause :
1. Connector connection failure 2.Thermistor failure 3. Main PCB failure
Check Point 1 : Check connection of Connector
Check if connector is removed.
Check erroneous connection.
Check if thermistor cable is open.
>>Upon correcting the removed connector or mis-wiring, reset the power.
OK OK
Check Point 2 : Remove connector and check Thermistor resistance value Check Point 2 :
Thermistor Characteristics (Approx. value)
Temperature
Resistance AR*18L/ 24L
Value (k )
AR*30L/36L/45L/54L
Temperature
Resistance
AR*18L/ 24L
Value (k )
AR*30L/36L/45L/54L
If Thermistor is either open or shorted, replace it and reset the power.
OK OK
Check Point 3 :
Check Point 3 : Check voltage of Main PCB (DC5.0V)
Make sure circuit diagram of outdoor unit and check terminal voltage at Thermistor (DC5.0V)
1 2
CN21
If the voltage does not appear, replace Main PCB.
Indicate or Display:
Outdoor Unit : LED 8 times blink
ERROR CODE : No indication
Detective details:
When Heat Sink Temperature Thermistor open or short-circuit is
detected at power ON or while running the compressor.
0°C 5°C 10°C
176 135
16.1 12.4
60°C 70°C 80°C
12.5 8.78
1.25 0.89
1 2 1 2 1 2
CN22 CN23 CN26
15°C 20°C
105 81.8 64.5
9.73 7.67 6.10
90°C 100°C
6.31 4.61 3.43
0.65 0.48 0.36
1 2
CN25
07-21
30°C
40°C 50°C
41.1 26.9 18.1
3.95 2.62 1.79
120°C
1.98
0.21