Weird compressor noise

[Fox4744]

Hey guys,
I apologize for not introducing myself previously (couldn't find that new member introduction thing) but I'm new to the forum and I have a 99 jeep cherokee classic with about 147k miles on it.
I was also hoping somebody might know what's going on with it. If the A/C is on there's a godawful rumbling sound that seems to come from under the floorboards if it's in park or brakes are applied and the compressor kicks on. The compressor is cycling somewhat fast, kicks on for about 15 seconds then goes off again. The A/C dies blow cold though. I've had some people tell me it's a vacuum hose leak and others say it's a bad compressor. Any info is greatly appreciated. Also, not sure this is the right forum so I apologize if it isn't.

[Mudderoy]

I was getting a rumble from the exhaust pipe bouncing on the transmission crossmember. It would only do it in park, or drive, stopped. It was worse when the A/C compressor came on.

Short cycling A/C compressor can be a sign of low freon (or what ever it uses)

[4.3LXJ]

It might help if you stepped outside the vehicle and tried to pinpoint where the noise is coming from. Pay attention to the efan. It might be the culprit. And the cycling is your refrigerant charge is a little low

[Fox4744]

I've listened to it outside the car and I can't seem to pinpoint where it's coming from. It goes away completely when the A/C is off. The engine isn't overheating even after several hours of highway driving so I think the fan is ok. Anything in particular I should look for with that? I'll check the freon levels next chance I get and see if that's part of the problem. I'm starting to think the guy who redid the A/C in the jeep before I bought it was a bit of a moron

[Brasscatz]

Had the same issue on my old cavalier. Weird rattling sound that got worse when I turned on the a/c. Turned out to be the timing chain tensioner....

[Fox4744]

It's not so much a rattling as a really low pitched rumbling. I'll try to get a recording of it tomorrow and see what you guys think. Thanks for all the pointers so far!

[Fox4744]

It's looking like a bad serpentine belt was causing the problem. Had that replaced and it quieted down