There is kind of a low frequency grinding noise (but not exactly) I believe is coming from the AC compressor/clutch unit whenever the AC is disengaged. Whenever I crank up the AC or the ECU engages the clutch for whatever reason it chooses periodically to do so, the noise disappears. It returns as soon as the clutch disengages.

For a while I thought it might be an idler pulley or something going bad so I was trying to ignore it but I went out there today to try and figure it out and it seems to be coming from the AC pump area. Also no amount of WD sprayed ln any moving bearing I could find seemed to change the sound at all. Only the ac clutch dis/re-engaging seemed to cause any change in sound. Not that I think WD is good lube just that it sure should cause a failing bearing to change noises for a second when it's flowing through there.

Is there any way to make it stop without replacing the whole assembly? Maybe squirt some lube somewhere or something? I'm pretty sure this means replace compressor/pump assembly or at least replace but figured I'd ask since this exact thing wasn't seen in my quick scan of search results.

This being mild weathered western WA state most every vehicle I've ever owned has gotten its AC removed for horsepower reasons except this Ram I have now. It's kinda nice really, but I still don't use it much. Unfortunately I don't know much about AC since I've never had to live with it much.

 

You can use a screwdriver (the longer, the better for safety) as a stethescope (spelling?). Put the tip on the a/c pump and the handle to your ear. Just be sure NOT to get to close to any moving parts, and watch for loose clothing so it doesn't get caught in anything. It'll amplify the noise. You can move it from one component to another to pinpoint the culprit.

I have one thats about 3 foot long that I use for this very purpose. It told me the tensioner was bad a few months ago, and is again now.

To check that I put the tip on the bolt that holds the pully on. Same with the idler.

 

Probably bearings in the a/c pulley clutch mechanism. You can replace just the clutch/pulley, without having to replace the entire compressor, or even discharge the a/c system.

 

I'm pretty sure I already isolated it to the AC assembly but getting a second opinion from the screwdriver will certainly happen before any cash changes hands.

This exercise has sure highlighted another benefit of efans for me. Sweet front of engine troubleshooting access.

 

Thanks for posting HeyYou. I'll read FSM about troubleshooting and redoing the AC clutch and see if it is something I'd try.

 

http://autorepair.about.com/library/faqs/bl249i.htm