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Installation and Maintenance
Service Manual
(4) Malfunction of Zero-crossing Inspection Circuit Malfunction of the IDU Fan Motor U8
Main detection points:
● Instant energization afte de-energization while the capacitordischarges slowly?
● The zero-cross detectioncircuit of the mainboard is defined abnormal?
Malfunction diagnosis process:
Turn power off for
1minute,the turn
back on
The unit returns to normal.
Conclusion:U8 is displayed due to
power off/on while the
capacitor discharges slowly.
U8 is still
displayed
The zero-cross detection circuit
of the mainboard is defined
abnormal.Replace the mainboard
with the same model
Yes
No
Start
End