Fujitsu AU G24LVLA Series Service Instruction page 42

Trouble shooting 7
INDOOR UNIT Error Method:
Indoor room thermistor error
Detective Actuators:
Indoor unit Controller PCB
Room temperature thermistor
Forecast of Cause :
1. Connector failure connection 2. Thermistor failure 3. Controller PCB failure
Check Point 1 : Check connection of Connector
Check if connector is loose or removed
Check erroneous connection
Check if thermistor cable is open
>>Reset Power when reinstalling due to removed connector or incorrect wiring.
OK
Check Point 2 : Remove connector and check Thermistor resistance value
Thermistor Characteristics (Rough value)
Temperature (°C)
Resistance Value ( )
Temperature (°C)
Resistance Value ( )
If Thermistor is either open or shorted, replace it and reset the power.
OK
Check Point 3 : Check voltage of Controller PCB (DC5.0V)
Make sure circuit diagram of each indoor unit and check terminal voltage at Thermistor (DC5.0V)
AU*G24LVLA
AR*G24LMLA
GRAY
1 1
CN5
GRAY
2 2
H/E (MID) Thermistor
1
CN7
2
Room Temp. Thermistor
BLACK
1 1
CN8
BLACK
2 2
If the voltage does not appear, replace Controller PCB.
Indicate or Display:
Refer to error code table.
Detective details:
Room temperature thermistor is open or short is detected always.
-10 -5 0
58.2 44.0 33.6
30 35 40
8.0 6.5 5.3
AB*G24LVTA
CN5
CN7
CN8
5 10 15
25.9 20.2 15.8
45
4.3
BLACK GRAY
1 1 1 1
BLACK
GRAY
2 2 2 2
H/E (MID) Thermistor
1
2
Room Temp. Thermistor
BLACK
1 1
BLACK
2 2
02-09
20 25
12.5 10.0
DC