Fujitsu ASU18RMLQ Service Instruction page 65

Trouble shooting 35
OUTDOOR UNIT Error Method:
4-way valve error
Detective Actuators:
Outdoor Unit Main PCB Circuit
Heat Exchanger Temperature
Thermistor (middle)
Indoor 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 thermistor
Isn't it fallen off the holder?
Is there a cable pinched?
>> Check characteristics of thermistor
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:
Refer to error code table.
Detective details:
The following condition is monitored every one minute after the
compressor operates consecutively for 19 minutes, and 7 min ST
operates when the condition is detected two times in succession.
< Cooling or Dry operation >
[Indoor heat exchanger temp (middle)] - [Room temp] > +10degC
< Heating operation >
[Indoor heat exchanger temp (middle)] - [Room temp] < -10degC
The compressor restarts after 7 min ST is released.
When the continuance operation time of the compressor becomes
19 minutes, it detect difference between the heat exchanger
temperature (middle) and room temperature again.
when protective function
permanently and displays an error.
02-39
repeats five times, the outdoor unit stops