Fujitsu AS*G24LFCA Service Instruction page 39

Trouble shooting 12
OUTDOOR UNIT Error Method:
Compressor Thermistor Error
Detective Actuators:
Outdoor unit Main PCB
Compressor temperature thermistor
Forecast of Cause :
1. Connector connection failure
Check Point 1 : Check connection of connector
Check if connector is removed.
Check if connector is 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
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 voltage of Main PCB (DC5.0V)
Make sure circuit diagram of outdoor unit and check terminal voltage at thermistor (DC5.0V)
AO*G24LFL
Thermistor
(Compressor temp.)
BROWN
3 3
CN64 2 2
BROWN
1 1
Thermistor
(Outdoor temp.)
BLACK
3 3
CN62 2 2
BLACK
1 1
Thermistor
(Discharge pipe)
BLACK
4 4
BLACK
3 3
CN61
BLACK
2 2
BLACK
1 1
Thermistor
(Heat exchanger)
If the voltage does not appear, replace Main PCB.
Indicate or Display:
Detective details:
When Compressor temperature thermistor open or short-circuit
is detected at power ON or while running the compressor.
2. Thermistor failure
0 5 10 15
169 130 101 79.1
70 80 90 100
8.70 6.27 4.60 3.43
AO*G24LFCC
Thermistor
(Compressor temp.)
BLACK
3 3
CN73 2 2
BLACK
1 1
Thermistor
(Outdoor temp.)
BLACK
3 3
CN70 2 2
BLACK
1 1
Thermistor
(Discharge pipe)
BLACK
4 4
BLACK
3 3
CN71
BLACK
2 2
BLACK
1 1
Thermistor
(Heat exchanger)
02-14
3. Main PCB failure
20 30 40
62.6 40.0 26.3 17.8
120
2.00
AO*G30LFT
Thermistor
(Compressor temp.)
BROWN
3 3
CN64 2 2
BROWN
1 1
Thermistor
(Outdoor temp.)
BLUE
3 3
CN62 2 2
BLUE
1 1
Thermistor
(Heat exchanger)
BLACK
3 3
CN65 2 2
BLACK
1 1
Thermistor
(Discharge pipe)
BROWN
3 3
CN63 2 2
BROWN
1 1
50 60
12.3