Fujitsu AS* A09LEC Service Instruction page 33

Trouble shooting 6
OUTDOOR UNIT Error Method:
Outdoor Discharge Pipe Temperature
Thermistor Error
Detective Actuators:
Outdoor unit Main PCB
Discharge pipe temperature thermistor
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 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 OK
Check Point 3 : Check voltage of Inverter PCB (DC5.0V)
Make sure circuit diagram of outdoor unit and check terminal voltage at thermistor (DC5.0V)
BLACK
1 1
BLACK
2 2
CN71
BLACK
3 3
BLACK
4 4
BLACK
1 1
CN70 2 2
BLACK
3 3
If the voltage does not appear, replace Main PCB.
Indicate or Display:
Refer to error code table.
Detective details:
When Discharge pipe temperature thermistor open or short-circuit
is detected at power ON or while running the compressor.
2. Thermistor failure
-30 -20 -10
1013.1 531.6 292.9
30 40 50
40.0 26.3 17.8
THERMISTOR
( HEAT EXCHANGER )
THERMISTOR
( DISCHARGE PIPE )
THERMISTOR
( OUTDOOR TEMP. )
3. Main PCB failure
-5 0 5 10
221.1 168.6 129.8 100.9
60
70 80 90
8.7
12.3 6.3 4.6
02-08
15 20
79.1 62.5
100 120
3.4 2.0