Fujitsu AU*G36LRLA Service Instruction page 78

Trouble shooting 31
OUTDOOR UNIT Error Method:
Low pressure error
Detective Actuators:
Outdoor unit Main PCB
Pressure sensor
Forecast of Cause :
1. Connector connection failure
Check Point 1 : Check connections of the Pressure sensor
Check if the terminal connection is loose.
Check if connector is removed.
Check if connector is erroneous connection.
Check if cable is open.
>> Upon correcting the removed connector or mis-wiring, reset the power.
OK
Check Point 2 : Check output voltage of Main PCB
Check voltage of Main PCB.
(Measure at Main PCB side connector)
>>1 pin(Red) - 3 pin(Black) DC5V
RED
1 1
WHITE
CN16 2 2
BLACK
3 3
If the voltage is not correct, replace Main PCB.
OK
Check Point 3 : Check if gas leak or less gas
Measure Gas pressure, if there is a leak, correct it.
>> If recharging refrigerant, make sure to perform
vacuuming and recharge the specified amount.
OK
Check Point 4 : Replace Pressure sensor
If Check Point 1 ~ 3 do not improve the symptom, replace Pressure sensor.
Indicate or Display:
Refer to error code table.
Detective details:
In cooling operation, 1 minute or more after compressor's start-up,
when pressure sensor detects 0.12 MPa or less for consecutive
5 minutes.
2. Pressure sensor failure
5%
PS
PRESSURE SENSOR
3. Main PCB failure
MPa MPa
02-33
4. Gas leak, less