Fujitsu AB 14LBAJ Series Service Instruction page 54

Trouble shooting 5
OUTDOOR UNIT Error Method:
Outdoor Heat Exchanger Temperature
Thermistor Error
Detective Actuators:
Outdoor Unit Main PCB Circuit
Heat Exchanger 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 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
CN25
If the voltage does not appear, replace Main PCB.
Indicate or Display:
Refer to error code table.
Detective details:
When Heat Exchanger Temperature Thermistor open or short-circuit is
detected at power ON or while running the compressor.
-10°C -5°C 0°C 5°C
27.8 21.0 16.1 12.4
1 2 1 2
CN23 CN22 CN21
10°C 15°C 20°C
9.63 7.56 5.98
1 2
02-15
25°C
30°C
4.77 3.84
DC