Midea Corona MSC-07CRN1 - 9.3 Diagnostic Charts & Failure Analysis

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9.3 Diagnostic Chart
9.3.1 After energizing, no indicator is lighted and the air conditioner can’t be operated.
Yes
Yes No
No Ye s
Yes
No
9.3.2 Resetting phenomenon often occurs during operation. (That is automatically entering to the status when
power is on.)
The reason is that the instantaneous voltage of main chip is less than 4.5V. Check according to the following procedure:
Yes
No Ye s
No
After energizing, the air conditioner can’t be operated
Check if AC220V power supply outputs to Indoor PCB.
Check if AC220V exists at the primary coil of transformer.
Indoor PCB is defective
Check if AC14.5V exists at the secondary coil of transformer.
Take off the secondary plug of transformer, and then check if
AC14.5V exists at the secondary coil of transformer.
The transformer is defective. Indoor PCB is defective
Resetting phenomenon often occurs during operation.
After changing indoor fan motor, check if the failure releases.
Indoor PCB is defective
Power supply circuit has problems.
After changing Indoor PCB, check if the failure releases.
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