Fujitsu ARU7RLF Service Instruction page 57

Trouble shooting 18
OUTDOOR UNIT Error Method:
Heat Ex. Thermistor Error
Detective Actuators:
Outdoor Unit Main PCB Circuit
Heat Exchanger Temperature Thermistor
Forecast of Cause :
1. Connector connection failure 2.Thermistor failure 3. Main 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(°F)
Resistance Value (k )
If Thermistor is either open or shorted, replace it and reset the power.
OK
Check Point 3 :
Check Point 3 : Check voltage of Main PCB (DC5.0V)
Make sure circuit diagram of outdoor unit and check terminal voltage at Thermistor (DC5.0V)
1 2
CN25 CN26
If the voltage does not appear, replace Main 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 or while running the compressor.
14°F 23°F 32°F
27.8 21.0 16.1
1 2
1 2 1 2
CN23 CN22
41°F 50°F 59°F 68°C
12.4 9.63 7.56 5.98
1 2
CN21
02-22
77°F
86°F
4.77 3.84
DC