Daikin FDMQ-R Series Service Manual

Troubleshooting for FTX, FVXS Series SiUS091601EA
135 Part 6 Service Diagnosis
5.6 Signal Transmission Error (Between Indoor Unit and
Outdoor Unit)
Error Code U4
Method of Error
Detection
The signal transmission data received from the outdoor unit is checked whether it is normal.
Error Decision
Conditions
The data sent from the outdoor unit cannot be received normally, or the content of the data is
abnormal.
Supposed
Causes
 Power supply voltage not as specified
 Reduction of power supply voltage
 Wiring error
 Breaking of the connection 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

Daikin FDMQ-R Series Specifications

General

Brand	Daikin
Model	FDMQ-R Series
Category	Air Conditioner
Language	English