Daikin FVXS09NVJU, Service Manual

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SiUS091601E Troubleshooting
Service Diagnosis 76
4.6 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 is not as specified.
„
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