Fujitsu AU*24LUAR Service Instruction page 62

Trouble shooting 3
INDOOR UNIT Error Method:
INDOOR UNIT
Room Temperature Sensor Error
Detective Actuators:
Indoor Unit Controller PCB Circuit
Room Temperature Thermistor
Forecast of Cause :
1. Connector connection failure 2.Thermistor failure 3. Controller 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
Check Point 2 : Remove connector and check Thermistor resistance value Check Point 2 :
Thermistor Characteristics (Approx. value)
Temperature
Resistance Value (k )
Temperature
Resistance Value (k )
If Thermistor is either open or shorted, replace it and reset the power.
OK
Check Point 3 : Check voltage of Controller PCB (DC5.0V)
Check Point 3 :
Make sure circuit diagram of indoor unit and check terminal voltage at Thermistor (DC5.0V)
1 2 1 2
1 2 1 2
CN7 CN8
If the voltage does not appear, replace Controller PCB.
Indicate or Display:
Indoor Unit
Outdoor Unit : No indication
ERROR CODE : E : 02 / 03
Detective details:
When Room Temperature Thermistor open or short-circuit is
detected at power ON.
0°C 5°C 10°C
33.6 25.9 20.2
40°C 45°C 50°C
5.30 4.35 3.59
THERMISTOR
(PIPE TEMP.)
THERMISTOR
(ROOM TEMP.)
: No LED
15°C 20°C 25°C
15.8 12.5 10.0
07-06
30°C 35°C
8.04 6.51