Well, my car has suddenly developed the constant whine from the engine bay. I have more or less isolated the problem, and I am pretty sure it is the ac bearing or idler pulley. The only reason I think it might be the idler pulley because the noise will only go away for alittle bit, weither I turn the ac on or off. After a few minutes, I can turn the ac back on and the noise will go away again for a few minutes. Does this sound familiar to anyone?

 

ac compresser probably

 

Yes, it sounds familiar and no I personally cannot tell you which it is based on what you've explained.

A bad AC pulley bearing may make noise whether the AC is on or off (been there done that). Noise from a bad tensioner pulley may make noise intermittently.

1. Loosen the tensioner.

2. Spin the tensioner pulley by hand... Noisey or rough? If yes, you’re done. If no move on to #3.

3. Spin the AC pulley by hand... Noisey or rough? If yes, you’re done. If no move on to #4.

4. Go get the appropriate belt to bypass the AC compressor and run it... Noisey? If yes, it’s the tensioner. If no, it’s the AC pulley.

 

Do the screwdrive to the ear test. Put one end on each device and the other (handle) in your ear. The device that transmitts the most noise is the culprit.

Easy test, takes 2 minutes and a long screwdrive or rod.

 

Im going to try all of those when I get home. And I forgot to mention, not sure if it matters or not, I have a UDP. But like I said, this noise just started and and I've had the udp for almost 6 months now. The power steering belt is a smaller size but the main acc belt is factory. But Im going to try all of those to see if I can isolate the problem.

 

I have a similar problem but the noise is muffled only wen I turn the front defogger on.
When I turn the blower off or direct the blower to the vents ,the wining/ rattling noise come back

 

I would guess you have something actually in your vents like a leaf or something. the vents and defogger probably hit the leaf different ways, making one way louder than the other.