Signal Transmission Error (Between Indoor Unit And Outdoor Unit) - Daikin FFQ09Q2VJUFFQ12Q2VJUFFQ15Q2VJUFFQ18Q2VJURX09QMVJURX12QMVJURX15QMVJURX18QMVJU Service Manual

SiUS091628EA
4.12 Signal Transmission Error (Between Indoor Unit and
Outdoor Unit)
U4
Error Code
Method of Error The signal transmission data from the outdoor unit is checked whether it is normal.
Detection
Error Decision The data sent from the outdoor unit cannot be received normally, or the content of the data is
abnormal.
Conditions
Supposed
Causes
Service Diagnosis
Power supply voltage out of specification
Reduction of power supply voltage
Wiring error
Breaking of the connecting wires between the indoor and outdoor units (wire No. 3)
Defective outdoor unit PCB
Short circuit inside the fan motor winding
Defective indoor unit PCB
Disturbed power supply waveform
Troubleshooting
76