Fujitsu AB*30LBAG series Service Instruction page 52

Trouble shooting 5
OUTDOOR UNIT Error Method:
Outdoor Heat Exchanger Temperature
Sensor 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
CN21 CN22
If the voltage does not appear, replace Main PCB.
Indicate or Display:
Indoor Unit
Outdoor Unit : LED 3 times blink
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
27.5 20.9 16.1
1 2 1 2 1 2
CN23 CN26
: Operation LED: Blink, Timer LED: 3 times blink,
Vertical swing LED: OFF
5°C 10°C 15°C 20°C
12.4 9.73 7.67 6.10
1 2
CN25
07-06
25°C 30°C
3.95
4.89
DC