SiUS071735EA
Troubleshooting
Service Diagnosis
74
4.11 Low-voltage Detection or Over-voltage Detection
Error Code
U2
Method of Error
Detection
Low-voltage detection:
An abnormal voltage drop is detected by the DC voltage detection circuit.
Over-voltage detection:
An abnormal voltage rise is detected by the over-voltage detection circuit.
Error Decision
Conditions
Low-voltage detection:
The voltage detected by the DC voltage detection circuit is below 180 ~ 196 V (depending on
the model).
The compressor stops if the error occurs, and restarts automatically after 3-minute standby.
Over-voltage detection:
An over-voltage signal is fed from the over-voltage detection circuit to the microcomputer (over
458 ~ 500 V, depending on the model).
The compressor stops if the error occurs, and restarts automatically after 3-minute standby.
Supposed
Causes
Power supply voltage out of specification
Defective DC voltage detection circuit
Defective over-voltage detection circuit
Defective PAM control part
Disconnection of compressor harness
Short circuit inside the fan motor winding
Noise
Momentary drop of voltage
Momentary power failure
Defective outdoor unit PCB
Summary of Contents for FDMQ-R Series
Page 12: ...SiUS071735EA 1 List of Functions Part 1 List of Functions 1 Functions 2...
Page 14: ...SiUS071735EA 3 Specifications Part 2 Specifications 1 Specifications 4...
Page 120: ...Check SiUS071735EA 109 Service Diagnosis 15 18 24 class R25105 1 2 3 4 Multimeter...
Page 122: ...Check SiUS071735EA 111 Service Diagnosis 15 18 24 class R20704 W V U DC_P1 DC_N1...
Page 140: ...Piping Diagrams SiUS071735EA 129 Appendix RX24RMVJU A 3D092249A...
