Low-Voltage Detection Or Over-Voltage Detection - Daikin FTX20K(2)V1B Service Manual

Troubleshooting
4.6

Low-voltage Detection or Over-voltage Detection

U2
Error Code
Method of Error
Low-voltage detection:
An abnormal voltage drop is detected by the DC voltage detection circuit.
Detection
Over-voltage detection:
An abnormal voltage rise is detected by the over-voltage detection circuit.
Error Decision
Low-voltage detection:
 The voltage detected by the DC voltage detection circuit is below 180 ~ 196 V (depending on
Conditions
 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
 The compressor stops if the error occurs, and restarts automatically after 3-minute standby.
 Power supply voltage is not as specified.
Supposed
 Defective DC voltage detection circuit
Causes
 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
55
the model).
(over 458 ~ 500 V, depending on the model).
SiBE041525F
Service Diagnosis