Noise from Compressor/Pulley Area (05 Subaru Forester)

subaru
airconditioning

#1

This is my first Subaru, and I absolutely love the vehicle; however, because of it, I’m very new to its mechanics. I bought it used from a friend, and I’ve been driving it for three weeks now, now this noise has come up and I want to verify what needs to be fixed before I start taking things apart. Perhaps you all know what noise this is coming from the compressor/ac idler pulley area?
Here are a couple of videos.

In case it does somehow matter, one of my knowledgeable friends asked me if it makes more noise when I turn, and the answer is no.
Also, the noise does not come through the speakers, and from what I understand, that eliminates an alternator problem.
Thank you all!


#2

Sounds like an alternator bearing to me. You can take a length of rubber hose and use it as a stethoscope to try and isolate the noise, but sound will transmit through metal so can be kind of hard to tell. From the severity of the noise though won’t be too long before something falls off of locks up. Take the belt off and spin the various pulleys by hand and listen and check for play. The idea of the noise coming through the speakers has nothing to do with worn bearings. I’ve had an alternator lock up before and spin the pulley right off.


#3

I agree that the noise is either from an alternator bearing or from an idler pulley bearing, either of which have gone dry.

The rubber hose method for locating the noise is a good one, but just be sure that you aren’t wearing a necktie, or a dangling neck chain, or have long hair dangling when you lean over the belt area.


#4

I might also add that the noise only occurs at start-up, lasts about a minute, then it goes away.


#5

That could describe either an alternator bearing problem or an idler pulley bearing problem.