Fujitsu AU G18LVLB Series Service Instruction page 71

Trouble shooting 27
OUTDOOR UNIT Error Method:
Heat Ex. Outlet Temp.
Thermistor Error
Detective Actuators:
Heat exchanger liquid 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 (CN147:1-2) voltage value = 5V
Remove the thermistor from Main PCB, check the voltage.
Heat exchanger outlet temperature thermistor
If the voltage do not appear, 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 : 73]
Detective details:
1 2 3 4
1 2 3 4
CN147
(CN147:1-2)
, and execute
Timer lamp: 3 time Flash
Economy lamp : Continuous flash.
Heat exchanger outlet temperature thermistor short or open detected
02-32
Outdoor unit :
PUMP LOW
POWER
DOWN NOISE
ERROR
(L1) (L2)
MODE
3
2 7
DC
PEAK
CUT
(L3) (L4) (L5) (L6)