Fujitsu AGU12RLF Service Instruction page 43

Trouble shooting 13
OUTDOOR UNIT Error Method:
Heat Ex.(Pipe) thermistor error
Detective Actuators:
Outdoor unit Main PCB
Heat exchanger 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 OK
Check Point 2 : Remove connector and check Thermistor resistance value
Check Point 2 :
Thermistor Characteristics (Approx. value)
Temperature (°F)
Resistance Value (k )
Temperature (°F)
Resistance Value (k )
If Thermistor is either open or shorted, replace it and reset the power.
OK 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)
AOU9/ 12RLFF
THERMISTOR
(PIPE)
BLACK
BLACK
BROWN
BROWN
THERMISTOR
(DISCHARGE)
THERMISTOR
(OUTDOOR)
BLACK
BLACK
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.
2.Thermistor failure
14°F 23°F 32°F
27.8 21.0 16.1 12.4
140°F 158°F 176°F
1.2 0.8 0.6
AOU15RLFF
THERMISTOR
(PIPE)
1 1
2 2
CN71
3 3
4 4
THERMISTOR
(DISCHARGE)
THERMISTOR
(OUTDOOR)
1 1
CN70
2 2
3 3
3. Main PCB failure
41°F 50°F 68°F 86°F
9.6 6.0
BLACK
1 1
BLACK
2 2
BROWN or BLACK
3 3
BROWN or BLACK
4 4
BLACK
1 1
2 2
BLACK
3 3
02-18
104°F 122°F
3.8
2.5 1.7
CN61
CN62