Fujitsu ASU 9RLF1 Service Instruction page 38

Trouble shooting 12
OUTDOOR UNIT Error Method:
Outdoor unit Heat Ex. sensor error
Detective Actuators:
Outdoor unit Main PCB
Heat exchanger temperature 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)
AOU9RLFW1
THERMISTOR
(PIPE)
BLACK
BLACK
BLACK
BLACK
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
-22°F -4°F 14°F 23°F
95.6 50.3 27.8
104°F 122°F 140°F 158°F
2.5 1.7 1.2
AOU12RLFW1
THERMISTOR
(PIPE)
1 1
2 2
CN61
3 3
4 4
THERMISTOR
(DISCHARGE)
THERMISTOR
(OUTDOOR)
1 1
CN62
2 2
3 3
3. Main PCB failure
32°F 41°F 50°F
21.0 16.1 12.4 9.6
176°F
0.8 0.6
BLACK
1
BLACK
2
BROWN
3
BROWN
4
BLACK
1
2
BLACK
3
02-15
68°F 86°F
6.0 3.8
1
2
CN71
3
4
1
CN70
2
3