SiUS092230EA
Troubleshooting for FDMQ, FFQ Series
Part 6 Service Diagnosis
153
6.10 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 RX-W Series
Page 1: ... Applied Models Inverter Pair Heat Pump Service Manual SiUS092230EA Inverter Pair RX W Series ...
Page 207: ...SiUS092230EA Check Part 6 Service Diagnosis 201 15 18 24 class R25105 1 2 3 4 Multimeter ...
Page 209: ...SiUS092230EA Check Part 6 Service Diagnosis 203 15 18 24 class R20704 W V U DC_P1 DC_N1 ...
Page 239: ...SiUS092230EA Piping Diagrams Part 8 Appendix 233 RX24WMVJU9 3D141502 ...