SiBE12-908 Troubleshooting
Service Diagnosis 156
2.32 Over Voltage Protection / Low Voltage Protection
Remote
Controller Display
U2
Method of
Malfunction
Detection
Detect an abnormal increase or drop of voltage by the over voltage detection circuit or DC
voltage detection circuit.
Malfunction
Decision
Conditions
When an over voltage signal is sent to the microcomputer from the over voltage detection
circuit, or the voltage detected by DC voltage detection circuit is less than 150 V and that
voltage continues for about 0.1 second.
The unit shuts down if the fault conditions occurs repeatedly.
Fault counter is reset when the unit continuously runs for 11 minutes without fault.
Supposed
Causes
Abnormal supply voltage, momentary power failure
Defective over voltage detector or defective DC voltage detection circuit
Failure in PAM controlled parts
Short circuit inside the fan motor winding.
Troubleshooting
(R9451)
Caution
Be sure to turn off power switch before connect or disconnect connector,
or parts damage may be occurred.
Check the supply voltage.
Supply voltage as
specified?
YES
NO
Correct the power supply.
Rotate fan by hand.
Does fan rotate
smoothly?
YES
NO
Turn on the power
again. System
restarted?
Repeat a
couple of times.
NO
YES
(Precaution before turning on the power again)
Make sure the power has been off for
at least 30 seconds.
Disturbance factors
∗
Noise
∗
Power supply distortion
Replace fan motor and
outdoor unit PCB.
Check for such factors for a
long term.
∗
Try to get restarted a
couple of times.
Replace the outdoor unit
PCB.
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