Cloggerdude

Just purchased a 2000 S2K with 66k miles and drove it home 3.5 hours. About halfway home I smelled a burning odor from the vents, but figured it might have been the car in front of me. It eventually went away.

Fast forward to when I got home and now the car makes a weird noise when you start it. Do some more investigating and it only makes the noise (like a belt rubbing sound) when the AC is turned OFF. Which is weird, because everything I read talks about sounds when the AC is on. Turn the AC on and the sound goes away and the AC seems to work normally.

Someone suggested it might be the AC Clutch, which wouldn’t be as bad as the whole compressor, but I can’t really find any guides for replacing just the clutch. I was going to take it to a mechanic tomorrow, but I’m kind of paranoid to run it now. Should I run it with the AC on, or leave it off? If it’s the clutch, is that something I could possibly do myself?

Any help would be greatly appreciated. It’s super frustrating to buy the car you’ve been excited about and almost immediately have it have a problem.

Car Analogy

Are you sure it isn't the infamous cold weather starter grind? That is nasty sounding yet innocuous whining or grinding noise the starter will make once it gets cold out. All S2000's do this if it gets cold enough outside.

Also, try removing or just loosening the serpentine belt, and see if you can still replicate noise. If you can't, and you try enough times to be confident you would have had the noise if the condition still existed, then you can be sure its a belt driven bearing issue. Obviously don't run car any length of time with belt removed.

If it is a belt driven bearing,it may not be the AC compressor. In fact, I bet its not. My bet is the extra load from AC on is causing the bearing that is going bad to not squeal.

I bet its tensioner or idler pulley bearing. Spin them by hand and make sure its smooth and no bad noise.

You can replace the whole pulley, it just bolts in place. Or just replace the bearings. Its a very common bearing, can buy on Amazon. Just press out old, press in new. Much cheaper fix.

There are diy instructions here of you search. Only gotcha is you can crack the pulley if you don't support it properly as you hammer bearing. Consult diy.

I did both pulleys while I had things apart. Its cheap enough, and if one went bad, other probably worn too.

I also looked on Amazon for a version of the bearing that was spec'ed for high rpm, since our motors rev so high. This is a very common bearing used in all manner of auto and industrial uses. So many different versions of it. All will fit, all will work. Some just won't last quite as long if its spec isn't well suited to application.

I replaced mine probably 50k miles ago, they've been flawless.

Cloggerdude

Thanks for that, it at least gives me a glimmer of hope. I called an AC repair place today and they said the entire compressor would likely need to be replaced. I’m going to try out your suggestions first though.

Car Analogy

What I'd really hate to see is you spend a large chunk of change to someone to mount an unneeded replacement compressor that is inferior to the stock one, and ends up not lasting as long as the stock one would have.

Aftermarket compressors are notorious for not lasting very long in this car. Probably due to the rpm range it sees. It has to be designed to spin fast enough at idle to still provide cooling, which is the same speed as any other 4 cyl, yet also handle whatever rpm compressor ends up at when crank spins 9k rpm.

Whatever you do, ask for old parts back. That way if a part wasn't really bad, at least you can still reuse it later when whatever inferior aftermarket part got installed goes bad.

Also, forgot to mention, spin compressor by hand as well. See if it feels ok. With clutch not engaged its just freewheeling. Should beabke to test same as other pulleys. Spin alternator and water pump as well. See how they feel.

Cloggerdude

Okay, it’s definitely something with the compressor. All other bearings spin freely (for the most part), but the AC compressor most definitely does not. I can turn it, but it’s not smooth at all and makes a noise as I’m doing it.

Since I’ve narrowed it down to that, and I’m already smelling burning, I assume there’s a high likelihood that the compressor itself has been damaged at this point?