Room Temp. Sensor Error - Fujitsu ASTG18KMTC Service Instruction

Trouble shooting 6
INDOOR UNIT Error Method:
INDOOR UNIT

Room temp. sensor error

Detective Actuators:
Indoor unit Controller PCB
Room 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
Check Point 2 : Check Point 2 : Remove connector and check Thermistor resistance value
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)
BLACK
1 1
BLACK
2 2
CN1
BLACK
3 3
BLACK
4 4
If the voltage does not appear, replace Controller PCB.
Indicate or Display:
Outdoor Unit : No indication
Indoor Unit
ERROR CODE : [E : 41]
Detective details:
When Room Temperature Thermistor open or short-circuit is detected.
2.Thermistor failure
-10°C -5°C 0°C
58.2 44.0 33.6
30°C 35°C 40°C
8.0 6.5 5.3
THERMISTOR
(PIPE)
THERMISTOR
(ROOM TEMP.)
: Operation lamp: 4 times Flash, Timer lamp: 1 time Flash
Economy lamp: Continuous flash.
3. Controller PCB failure
5°C 10°C 15°C
25.9 20.2 15.8
45°C
4.4
02-16
20°C 25°C
12.5 10.0