Fujitsu AU A36LCLU Series Service Instruction page 57

Trouble shooting 13
OUTDOOR UNIT Error Method:
Heat Sink Thermistor (PFC) Error
Detective Actuators:
Outdoor Unit Main PCB
Heat Sink Temperature Thermistor (PFC)
Forecast of Cause :
1. Connector connection failure
Check Point 1 : Check connection of connector
Check if connector is removed.
Check if connector is 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 Main PCB (DC5.0V)
Make sure circuit diagram of outdoor unit and check terminal voltage at thermistor (DC5.0V)
BLACK
BLACK
BLACK
BLACK
BROWN
BROWN
BLACK
BLACK
BLUE
BLUE
BROWN
BROWN
If the voltage does not appear, replace Main PCB.
Indicate or Display:
Refer to error code table.
Detective details:
When Compressor Temperature Thermistor (PFC) open or
short-circuit is detected at power ON or while running the compressor.
2. Thermistor failure
0 5 10 15
15.8 12.2 9.5 7.5
60 70 80 90
1.17 0.83 0.60 0.44
THERMISTOR
( HEAT EXCHANGER MID. )
THERMISTOR
( HEATSINK PFC )
THERMISTOR
( DISCHARGE PIPE )
THERMISTOR
( HEAT EXCHANGER OUT )
THERMISTOR
( OUTDOOR TEMP. )
THERMISTOR
( COMPRESSOR TEMP. )
02-16
3. Main PCB failure
20 30 40 50
5.9 3.78 2.50 1.69
100 110 120
0.33 0.25 0.19