Low-Voltage Detection Or Over-Voltage Detection - Daikin SUPER MULTI NX CTXS07JVJU Service Manual

Troubleshooting for Outdoor Unit
6.2

Low-voltage Detection or Over-voltage Detection

U2
Remote
Controller
Display
Outdoor Unit LED A 5
Display
Method of  Indoor Unit
Malfunction
The zero-cross detection of the power supply is evaluated by the indoor unit PCB.
Detection
 Outdoor Unit
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.
 Indoor Unit
Malfunction
Decision
There is no zero-cross detection in approximately 10 seconds.
Conditions
 Outdoor Unit
Low-voltage detection:
 The voltage detected by the DC voltage detection circuit is below 150 V for 0.1 second.
 If the error repeats, the system is shut down.
 Reset condition: Continuous run for about 60 minutes without any other error
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.
 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
 Noise
 Momentary fall of voltage
 Momentary power failure
 Defective indoor unit PCB
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SiUS12-928_B
Service Diagnosis