Newbie here. Recently purchased a 04 Sable, been running great overall. However, have recently noticed a strange whinning noise from under the hood during acceleration while A/C is running. Runs normal with no noise when A/C is off. I'll be at a light, then accelerate to speed and I'll hear this whinning or humming noise as I get up to speed, say 40-45 mph in the city, then it stops while Im cruiseing. But as soon as the next light gets me, it starts all over again as I accelerate. I've also notice a rough idle as Im sitting at the light waiting for green. Again, with the A/C on.

No A/C running.....no noise, no rough idle, runs great. Any ideas?

I live in Phoenix, so no A/C is not an option during the summer. :(

Thanks.

sounds like your a/c compressor, and or bearings are shot,which ismaking it hard for your engine to turn it. when the a/c is off, the compressor spins freely, when it is on, it engages the compressor.once you get cruising the engine makesenough power or has enough inertia to spin the compressor. at idle, the engine is not making enoughpower to turn your faulty compressor, plus the power steering pump, water pump, and the alternator. (hence the rough idle) I would say your bearings in your a/c compressor are shot, which is the ugly humming sound you are hearing. the whinning could be a combination of the bearings, or the belt slipping around the compressor pulley. call your local junkyard for a whole unitif $ is an issue. a/c compressors are big bucks. even having the bearings replaced would be quite pricey i'd imagine. until then, shut off the a/c when you are idling. good luck.let me know how it turns out.&n bsp;p.s. if you aren't ado-it-yourselferand you don't have a trustworthymechanic, get a second, third and fourth opinion on diagnosis, prices, etc.

Thanks. I'll take it in for a check. Its a shame if thats the case, as the vehicle only has 39,000 miles. You'd think they'd last longer than that.

Thanks again.

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yeah, I hope it is something cheaper like a tensioner pulley. But living in Arizona i'm sure the a/c has been on since it was purchased from the dealer. let me know how things play out. stay cool! ha ha ha!

Well, finally took it in and here's the damage. $1,200 A/C unit fried!

New compressor, new clutch, all new o rings, evacuate and recharge, blah blah blah...etc, etc!!! Unbelievable after only 39,000 miles.

But there is a silver lining. When I purchased the car, I also purchased an extended warranty. Never thinking I'd have to use it so soon, and on an '04. Thank goodness everything was covered under the warranty. Only had to pay the deductible, $100. So I dodged a major bullet.

For those of you that think a warranty is unnecessary, saying its a waste of money...take this advice. No matter where, or when the car was purchased, you gotta buy the extended warranty, after market or dealer offer. Today's vehicles are far too advanced and technical, that to not cover yourself is foolish. I just saved myself over $1,000!! Don't take a chance. You never know.

Thanks conan. You were dead on with the diagnosis.

thank god for silver linings. andnow for realthis time,stay cool! Edited by: conan312