Daikin AT12BV1LS Pocket Manual page 145

Troubleshooting
5.3.10 Outdoor Unit PCB Abnormality or Signal
Transmission Circuit Abnormality
Remote
Controller
Display
Method of
Malfunction
Detection
Malfunction
Decision
Conditions
Supposed
Causes
144
U4
The data received from the outdoor unit in indoor unit-
outdoor unit signal transmission is checked whether it is
normal.
When the data sent from the outdoor unit cannot be
received normally, or when the content of the data is
abnormal.
If the indoor unit cannot communicate with the outdoor
unit for 15 seconds, the system will be shut down.
Faulty outdoor unit PCB.
Faulty indoor unit PCB.
Indoor unit-outdoor unit signal transmission error due
to wiring error.
Indoor unit-outdoor unit signal transmission error due
to breaking of wire in the connection wires between
the indoor and outdoor units (the transmission wire).
Si10-417
Service Diagnosis