Fujitsu AU G18LVLB Series Service Instruction page 72

Trouble shooting 28
OUTDOOR UNIT Error Method:
Outdoor Thermistor Error
Detective Actuators:
Outdoor temperature thermistor
Forecast of Cause :
1. Connector connection defective, open
2. Thermistor failure
3. Main PCB failure
Check Point 1 : Check the connector connection and cable open
Connector connection state check
Cable open check
OK
Check Point 2: Check the thermistor
Thermistor characteristics check (Disconnect the thermistor from the PCB and check.)
* For the thermistor characteristics, refer to the "Service Parts Information 8".
OK
Check Point 3 : Check voltage of Main PCB (DC5.0V)
Main PCB (CN144:1-3) voltage value = 5V
Remove the thermistor from Main PCB, check the voltage.
CN144
Outdoor temperature thermistor (CN144:1-3)
If the voltage do not appear, replace Main PCB If the voltage do not appear, replace Main PCB
the check operation again.
Indicate or Display:
Indoor Unit : Operation lamp: 7 time Flash,
ERROR CODE : [E : 74]
Detective details:
Outdoor temperature thermistor short or open detected
1 2 3
1 2 3
, and execute
Timer lamp: 4 time Flash
Economy lamp : Continuous flash.
DC
02-33
Outdoor unit :
PUMP LOW
POWER
DOWN NOISE
ERROR
(L1) (L2) (L3) (L4)
MODE
7 4
2
PEAK
CUT
(L5) (L6)