Indoor Heat Exchanger Temperature Sensor Error - Fujitsu AB A30LBT Series Service Instruction

Trouble shooting 4
INDOOR UNIT Error Method:
Indoor Heat Exchanger Temperature
Sensor Error
Detective Actuators:
Indoor Unit Controller PCB Circuit
Heat Exchanger 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
Thermistor Characteristics (Approx. value)
Temperature (°C )
Resistance Value (k )
Temperature (°C )
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)
Make sure circuit diagram of indoor unit and check terminal voltage at Thermistor (DC5.0V)
1 1
CN 8
2 2
Cable color
AB, AR : BLACK
1 1
CN 7 AU
2 2
1 1
CN 5
2 2
Cable color
AR : GRAY
AU : BLACK
AB Type
1 1
CN 5
2 2
BLACK
If the voltage does not appear, replace Controller 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.
0 5
176 134
40 45
25.6 20.8 17.1
THERMISTOR
(ROOM TEMP.)
: RED
THERMISTOR
(PIPE TEMP.)
1 1
2 2
GRAY
10 15 20
103 80.3 62.9
50
02-08
25 30 35
49.7 39.6 31.7
DC