Fujitsu AUG12LVLB Service Instruction page 50

Trouble shooting 15
OUTDOOR UNIT Error Method:
Outdoor unit Heat Ex. liquid temp.
sensor error
Detective Actuators:
Outdoor unit Main PCB
Heat exchanger temperature thermistor
Forecast of Cause :
1. Connector connection 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(°C)
Resistance Value (k )
Temperature(°C)
Resistance Value (k )
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 3
1 2 3
CN70
If the voltage does not appear, replace Main PCB.
AMP Air Conditioning
Indicate or Display:
Refer to error code table.
Detective details:
When the heat exchanger temperature thermistor open is detected
at power ON or while running the compressor.
2.Thermistor failure
-30 -20 -10
95.6 50.3 27.8
60 70 80
1.2 0.8 0.6
1 2 1 2 1 2 3 4
1 2 1 2 1 2 3 4
CN72 CN73 CN71
3. Main PCB failure
0 10 20 30
16.1 9.6 6.0 3.8
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2.5 1.7
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