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SiUS091601EA
Troubleshooting for FDMQ Series
Part 6 Service Diagnosis
148
6.9 Signal Transmission Error (Between Indoor and Outdoor
Unit)
Error Code
U4
Method of Error
Detection
The signal transmission data 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 out of specification
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
Summary of Contents for FDMQ12RVJU
Page 18: ...SiUS091601EA 13 Part 2 Specifications 1 Specifications 14 Part 2 Specifications ...
Page 198: ...Check SiUS091601EA 193 Part 6 Service Diagnosis 18 24 class R24538 1 2 3 4 Multimeter ...
Page 201: ...SiUS091601EA Check Part 6 Service Diagnosis 196 18 24 class R24539 DC DC W V U ...
Page 229: ...SiUS091601EA Piping Diagrams Part 8 Appendix 224 RXL15QMVJU RXL18UMVJU 3D100007 3D123368 ...
Page 230: ...Piping Diagrams SiUS091601EA 225 Part 8 Appendix RXL24UMVJU 3D107985A ...