How can I trouble shoot this?

when I turn the A/C on I will have cool air and good airflow but there’s a buzzing noise.

I have replace the cabin air filter and made sure the intake vents right below the windshield are not obstructed, but still having that noise.

Could someone give a few steps or key points to check first?

thanks

 

Do you get the same noise if you turn the heat on?

 

You may have something in the blower fan

 

Ditto on this, could be a leaf/twig/anything touching the fan cage.


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