Fujitsu ARYG72LHTA Service Instruction page 62

Trouble shooting 25
OUTDOOR UNIT Error Method:
Heat Sink Thermistor Error
Detective Actuators:
Heat sink temp. thermistor
Forecast of Cause :
1. Connector connection defective, open
2. Sensor defective
3. Transistor PCB defective
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 sensor from the PCB and check.)
* For the sensor characteristics, refer to the "Service Parts Information 8".
OK
Check Point 3 : Check voltage of Inverter PCB (DC5.0V)
Transistor PCB (CN360: 1-2) voltage value = 5V
Remove the sensor from Inverter PCB, check the voltage.
THERMISTOR (HEATSINK TEMP.)
BLACK
1 1
CN360
2 2
BLACK
Heat sink temp. thermistot (CN360: 1-2)
If the voltage does not appear, replace Inverter PCB.
Indicate or Display:
Error code : 77
Detective details:
Heat sink temp. thermistor open/short detected
DC
02-26
Outdoor unit :
PUMP LOW
POWER
DOWN NOISE
ERROR
(L1) (L2) (L3) (L4)
MODE
7 7
2
PEAK
CUT
(L5) (L6)