[rothwem]

When I start the car on cooler mornings (<70F) when the A/C has been on from the afternoon before, I'm finding that the pulley in the engine bay is really loud. Turning off the A/C makes the noise go away, but I'm kinda wondering what the heck is going on. If the car warms up, turning the air conditioning on results in no noise either. The air out of the vents is ice-cold too, no issues with function here.

The sound is a whine, it sounds like a bearing going bad.

I bought a new belt and tensioner kit and I'll throw it on this weekend, another other thoughts about solutions? Any similar experience with a noisy A/C?

[avocet]

With domestic ac compressors I have found the clutch bearing makes more noise when it(the ac) is off. When the clutch is engaged it stabilizes the clutch/pulley and transfers the load into the compressor output bearing. When the clutch is released, the pulley is now spinning completely on the clutch bearing.

What I am trying to say is that from my experience(that only included domestic compressors) is it sounds like your compressor bearing(s) is/are shot...

[frisbeeguy]

Originally Posted by rothwem

When I start the car on cooler mornings (<70F) when the A/C has been on from the afternoon before, I'm finding that the pulley in the engine bay is really loud. Turning off the A/C makes the noise go away, but I'm kinda wondering what the heck is going on. If the car warms up, turning the air conditioning on results in no noise either. The air out of the vents is ice-cold too, no issues with function here.

The sound is a whine, it sounds like a bearing going bad.

I bought a new belt and tensioner kit and I'll throw it on this weekend, another other thoughts about solutions? Any similar experience with a noisy A/C?

Not sure if this applies to BMWs, but on Honda's, whenever this noise happens, it's caused by the compressor clutch bearing (like the other post said), and the procedure is to replace the entire compressor.

[rothwem]

Originally Posted by frisbeeguy

Not sure if this applies to BMWs, but on Honda's, whenever this noise happens, it's caused by the compressor clutch bearing (like the other post said), and the procedure is to replace the entire compressor.

Damn, that's kinda what I was thinking. Is it similar symptoms, only noisy when cold, then quiets down when warm?

[rjahl]

Just make sure you check the simple and more frequent failure first. Idler pulley bearings fail way more often then the AC compressor.

[frisbeeguy]

Originally Posted by rothwem

Damn, that's kinda what I was thinking. Is it similar symptoms, only noisy when cold, then quiets down when warm?

Yeah similar symptoms as you described... happened to my Honda Civic, and it was diagnosed as a bad compressor...replaced the compressor, and that fixed the issue.