When idling with A/C on at a stoplight, I hear a low pitched whirring sound that almost sounds like a belt that is too tight. The noise gets more pronounced when I apply the brakes or turn the steering wheel. Only happens at idle and when the A/C is on. A/C still blows cold air. Once I raise the RPMs and pull away from the light, the noise is gone. Just started making this noise recently. The car has 102k miles and had it's 100K servicing done in Fall of 2011 at the dealership.

 

It could definitely be a belt tension problem. Did the 100K mile service include new serpentine and power steering belts?

 

Yes, the 100k service included ALL belt replacements. Strange that you ask this, because right after the 100k service, I had a constant whirring noise that would rise with RPMs as I drove. I took the car back to the dealer, and they determined the timing belt was too tight. They loosened the timing belt a little bit and the noise was gone. What's weird is the noise I'm experiencing now just showed up recently and only can be heard with A/C on at idle. You still think it's one of the belts too tight?

 

One of the two belts (not the timing belt) could be too loose or too tight.

I found on my 95 accord that the serpentine belt was typically the culprit for belt noise. I would try tightening it a bit to see if the noise gets better or worse.

 

Is the serpentine something I can tighten/loosen pretty easily on my own just to experiment? Is there a nut I can turn (so to speak)? I have a Honda shop manual (both Volume 1 & 2), I guess I could look in there.