Indoor Heat Exchanger Temperature Sensor Error - Fujitsu ASU9RL Service Instruction

Trouble shooting 4
INDOOR UNIT Error Method:
INDOOR UNIT
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 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)
Make sure circuit diagram of indoor unit and check terminal voltage at Thermistor (DC5.0V)
1 2 3 4
1 2 3 4
CN4
If the voltage does not appear, replace Controller PCB.
Indicate or Display:
Outdoor Unit
Indoor Unit
ERROR CODE : [E : 04]
Detective details:
When Heat Exchanger Temperature Thermistor open or short-circuit is
detected at power ON.
32°F 41°F 50°F
(0°C) (5°C) (10°C)
176 134 103
104°F 113°F 122°F
(40°C) (45°C) (50°C)
25.6 20.8 17.1
THERMISTOR
(PIPE TEMP.)
THERMISTOR
(ROOM TEMP.)
06-08
: No indication
: Operation LED : 2 times, Timer LED : 3 times
59°F 68°F 77°F
(15°C) (20°C) (25°C)
80.3 62.9 49.7
86°F 95°F
(30°C) (35°C)
39.6 31.7