v944god

Just got another problem with the car out of nowhere.

All of a sudden I'm getting this annoying loud screech from my belts! Aghh

Doesn't seem like a big problem, but that damn sound is louder than my stereo.

Ok, here is what I discovered. Everytime I run the a/c, fan, or anything like that the belt makes that awful noise. As soon as I turn them off, its quiet as a kitten. Do you guys think its the a/c belt? The sound also seems to happen at certain rpms, mostly 1st and 2nd gear between 1-4k rpms. As soon as I get past 4k rpms in first it stops. Or if I go WOT it will stop.

Jason_86_951

The bearing in the AC is going out. During WOT the clutch disengages, that why it stops.
Jason

v944god

So im going to need a new a/c clutch or an entirley new compressor?

scottz

One side of the expansion mechanism that goes between the ac and mounts to the engine broke on mine - had the same symptoms. It broke right where the bolt goes into the ac. It was still tensioned but could wiggle some.

IceShark

I'd first check the A/C & alternator belt for slipping. The noise seems to come when you load the belt with the A/C compressor or load the alternator with a high electrical demand. Thus the screech. The noise quiting at high RPMs is because the belt is whipping around so fast that it gets enough bite on the pullies.

That belt is supposed to be tensioned quite high - 85 lbs, which is really tight.

Phil Harrison

Check the tension on the A/C / Alternator belt first. I had the same pb on my 968, it has to be pretty damn tight.

v944god

So if I can get some slack on the belts, its not tight enough?

Phil Harrison

I think you're supposed to have 5 mm travel on the longest section ( i.e. pull & push perpendicular to direction of travel.)

FSAEracer03

"Check the tension on the A/C / Alternator belt first. I had the same pb on my 968, it has to be pretty damn tight."

"I think you're supposed to have 5 mm travel on the longest section ( i.e. pull & push perpendicular to direction of travel.)"

WOW, I'm glad somebody said that... all you guys predicting the end of his A/C compressor and/or clutch were starting to worry me Chances are it's just a stretched belt. If they are old, just replace them (A/C and PS... only $15 total or so); if not, just retension them... I'd be willing to put a fair amount of money on the squeel being the A/C belt looseness. Our friend Phil here is spot on with his info... v944god, you owe him a beer.

IPSC

I just replaced the AC / alternator belt on both my 944S and my 951 and I have been fighting belt noise on both cars. I used Dayco belts and both seem to have streched a great deal since I installed them. 5mm of travel is TINY I did not realize they were supposed to be that tight. I was concerned with putting tooo much stress on the pullies. That helps,

IPSC

hosrom_951

Make sure the a/c-alt belt is good (take it out and bend it, look inside the grooves fro tiny cracks) same goes for the PS belt.

Make sure the tension on these belts are tight (not too tight, i think if you press it inwards with your finger, it shouldn't excees 2cm or so), and make sure that the tensioner(s) themselves are in good condition.

On my 88 NA, the a/c-alt tensioner used to keep coming loose after a week or so of driving, replaced it for a new one ($30) and cured the problem.

Peckster

Could be a generator bearing too. They can make a screeching sound under load when they're on the way out.

OriginalSterm

i had two rollers that had seized bearings and they screeched pretty bad. but, i don't think it mattered if i had the a/c on or not.

try checking the tension first (if you already haven't). seems the easiest and most obvious place to start.

hosrom_951

Start with the basics first (always cheaper and you get to save a few bucks) then start looking for the major things.

badass951

I am going to put my money on the alternator being shot. When was the last time the belts were done? This happened to me right after my belts were changed, as they were overtensioned.