Fujitsu AU G24LVLA Series Service Instruction page 51

Trouble shooting 16
OUTDOOR UNIT Error Method:
Outdoor temp. sensor error
Detective Actuators:
Outdoor unit Main PCB
Outdoor 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 CN72
If the voltage does not appear, replace Main PCB.
Indicate or Display:
Refer to error code table.
Detective details:
When the outdoor temperature thermistor open or short-circuit is
detected at power ON or while running the compressor.
2.Thermistor failure
-30 -20
224.3 115.2
50 60
3.5 2.4
1 2 3 4
1 2 1 2
1 2 1 2 1 2 3 4
CN73 CN71
3. Main PCB failure
-10 0 10
62.3 35.2 20.7
70 80
1.6 1.2
02-18
20 30 40
12.6 8.0 5.2