Rattling Noise/Hiss - Jeep Compass Forum
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post #1 of 2 Old 06-24-2015, 03:11 AM Thread Starter
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Join Date: Jun 2015
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Unhappy Rattling Noise/Hiss

New to the site, but I have a 2008 Jeep Compass 2.4L. Lately I've heard a kind of rattling or knocking noise coming from the serpentine area. I took the vehicle to a garage and they told me that my AC/Comp is going out and I'd need to replace it. I had a couple friends listen and look at her and they agree that that is most likely the problem. I don't know anything about cars really, but I almost feel like it could be something else.

I've been saving up to have her fixed, but from time to time I will turn on the AC and listen to the engine. So far, it's blown icy cold every time and the noise has gotten slightly louder after a short amount of time. Makes sense.. but the rattling continues before and after the AC is turned on and off. Not only that, but today as I pulled off of the interstate (it's our only vehicle), my electrical systems shut off and came right back on. All of my dash lights came on and went off, except the battery light. It is still on. My lights have slightly dimmed, but I made it back home thankfully. I checked my belt, and it looks fine. Evenly worn, but no unusual marks or tears. It looks normal..

Has anybody had this issue before? Is there any chance that it could be the alternator and not the AC/Comp? Maybe both? Any advice is appreciated. I'm scheduled to drop almost a grand this Friday, so hopefully I can have some questions for the mechanic. They are always good to me, so I believe their recommendation. The symptoms just don't line up to me. If it were the AC/Comp, would the AC no longer blow cold? Thanks for any help!
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post #2 of 2 Old 06-24-2015, 12:36 PM
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Join Date: Mar 2010
Location: Belleville, ON, Canada
Posts: 1,897
First of all don't guess and fix what someone guesses!!!

The compressor is not engaged if the AC is not turned on and typically will cycle after running. The engagement clutch is all that turns on the end. I might be bad (bear or such) and can be determined when the serpentine belt is removed.

Most like cause is the Alternator (ADP) pully is gone and now the alternator failed because of it. This has be a known failure point on 2007 where very common. Its not a standard solid pulley. There is a clutch mechanism inside and fails forcing the owner to replace the entire alternator ( a big job). The AC compressor needs moving out of the way to get the alternator out the bottom. There is a thread on that process here in this forum SEARCH!

If you are taking it to a garage especially now have the alternator checked thoroughly. The other pulleys can be easily checked with the belt off. You can get a rebuilt alternator which will come with a new ADP pulley.

A failing ADP on the alternator can make a lot of noise and it eventually causes the alternator bearing to fail as well creating a big mess in the alternator.

Jeep Compass 2009
4x4, 2.4L, CVT
North Edition
heated seats, TPMS
General Altimax RT43 P225/65R17
Yellow Fog Lamps
CLASS III Curtis Hitch
SOLD @ 153,000km Oct. 2018 THE END !!
Belleville, Ontario, Canada

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