Fujitsu AO G24LBCB Series Service Instruction page 34

Trouble shooting 5
INDOOR UNIT Error Method:
External communication error
Detective Actuators:
External communication error
Forecast of Cause :
1. Connection failure
Check Point 1 : Check the connection
Check any loose or removed connection of between the controller PCB to the external I/OPCB
>>If there is an abnormal condition, correct it by refer to installation manual or
the technical manual.
Check the condition condtion on the external I/O PCB and the controller PCB
(If there is loose connector, open cable or mis-wiring)
OK OK
Check Point 2: Replace external I/O PCB
If Check Point 1 do not improve the symptom, change External I/O PCB.
OK OK
Check Point 3: Replace Controller PCB
If Check Point 2 do not improve the symptom, change Controller PCB.
Indicate or Display:
Error code : 18
Detective details:
After receiving a signal from the external I/O PCB,
the same a signal has not been received for 15sec
2.External I/O PCB failure 3.Controller PCB failure
02-06
Outdoor unit : No indication