Fujitsu AB F18LAT Series Service Instruction page 60

Trouble shooting 27
OUTDOOR UNIT Error Method:
4-way valve error
Detective Actuators:
Outdoor Unit Main PCB Circuit
Heat Exchanger Temperature
Thermistor (Outlet)
Outdoor Temperature Thermistor
4-way valve
Forecast of Cause :
1. Connector connection failure 2. Thermistor failure 3. Coil failure 4. 4-way valve failure
5. Main PCB failure
Check Point 1 : Check connection of Connector
Check if connector is removed.
Check erroneous connection.
Check if thermistor cable is open.
>>Upon correcting the removed connector or mis-wiring, reset the power.
OK OK
Check Point 2 : Check Heat exchanger temp. thermistor and Outdoor temp. thermistor
Isn't it fallen off the holder?
Is there a cable pinched?
>> Check characteristics of thermistor (Refer to Trouble shooting 5, 7),
If defective, replace the thermistor
OK OK
Check Point 3 : Check the solenoid coil and 4-way valve
[ Solenoid coil ]
Remove CN30 from PCB and check the resistance value of coil.
Resistance value is about 1.4k
>>If it is Open or abnormal resistance value, replace Solenoid Coil.
[ 4-way valve ]
Check each piping temperature,
and the location of the valve by the temperature difference.
>>If the value location is not proper, replace 4-way valve.
OK OK
Check Point 4 : Replace Main PCB
If Check Point 1- 3 do not improve the symptom, replace Main PCB.
Indicate or Display:
Outdoor Unit : No indication
ERROR CODE : E : 2c
Detective details:
When the outdoor heat exchanger temperature is compared with
the outdoor temperature, and either following condition is detected
continuously two times, the compressor stops.
Cooling or Dry operation
[Outdoor heat exchanger temp.] - [Outdoor temp.] < -10degC
Heating operation
[Outdoor heat exchanger temp.] - [Outdoor temp.] > +10degC
the compressor stops permanently.
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