Low-Voltage Detection Or Over-Voltage Detection - Daikin 3MKS50E3V1B Service Manual

Troubleshooting for Outdoor Unit
7.2

Low-voltage Detection or Over-voltage Detection

U2
Remote
Controller
Display
Outdoor Unit LED
A
Display
Method of
Malfunction
The zero-cross detection of the power supply is evaluated by the indoor unit PCB.
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.
Malfunction
Decision
There is no zero-cross detection in approximately 10 seconds.
Conditions
Low-voltage detection:
Over-voltage detection:
Supposed
Causes
298
j i h h i
1 2 3 4
Indoor Unit
Outdoor Unit
Indoor Unit
Outdoor Unit
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
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.
Defective DC voltage detection circuit
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
h
5
SiBE121135
Service Diagnosis