Oldsmobile/Buick Repair: sounds, belt pulley, pontiac montana

Question
I just got a used 1999 Pontiac Montana van. I love it. It has been hot out so I have been running the air conditioner alot. One day it was cool and I shut off the air but left the blower on. I heard a noise as soon as the air was shut off. It would stop if I turned the air back on or put it in defrost. The dealer told me it was the clutch/pump and replaced that. I just picked it up and not it makes the "spinning type sound" WHEN THE AIR IS ON= just the opposite as before.  What the heck is going on. Both times it sounds like a spinning type sound like a belt on the pullies would make. Help

Answer
Hello Mary Lou,
That's going to be a hard one for me to help with, this far away.
I dounds for sure belt caused, and there are several possibilities.
At first I was thinking compressor clutch bearing, which it still could be.
But any of the belt driven accessories could be the culprit, as well as idler pulleys.
The age and condition of the belt itself is another.
One thing that can make the sound change like you first describe, is the tension of the belt. It changes a lot when the compressor is operating, which it does during both a/c and defrost.

It is possible now that just adjusting the tension might be needed, but I would at least return to the dealer that did the work and express your concern, hopefully with the service manager or a mechanic hearing the noise, not a service writer. Try to have the car making the noise when you arrive.

They are liable to tell you "Oh, that is normal." Ask them to show you the same noise on a new one.

Removing the belt, and rotating each belt pulley can often find the noise if a bearing is the problem.

Van