Fujitsu ASU18RMLQ Service Instruction page 46

Trouble shooting 13
OUTDOOR UNIT Error Method:
INDOOR UNIT
Pressure Switch Error
Detective Actuators:
Outdoor Unit Main PCB Circuit
Pressure Switch
Forecast of Cause :
1. Connector connection failure
Check Point 1 : Reset Power Supply and operate
Does abnormal LED indication show again?
YES YES
Check Point 2 : Check voltage of Main PCB (DC5.0V) Check Point 3 :
Make sure circuit diagram of outdoor unit and check terminal voltage
at Pressure Switch. (DC5.0V)
PRESSURE SWITCH 1
RED
1
RED
CN37
2
PRESSURE SWITCH 2
RED
1
RED
CN36
2
If the voltage does not appear, replace Main PCB.
OK
Check Point 3 : Check Pressure Switch
Check if connector is loose or cable is open.
>> If no abnormal connection is found,
replace Pressure Switch.
After replacing Pressure Switch, check operating
condition and pressure in operation.
OK
Check Point 4 : Check High Pressure Protection on cooling
Check Excessive high pressure protection on cooling.
(Refer to Trouble shooting 31)
Indicate or Display:
Refer to error code table.
Detective details:
When pressure switch open is detected in 10 seconds
after the power is turned on.
2. Pressure Switch failure
NO NO
02-20
3. Main PCB failure