lexlyf

Has anyone experienced problems with their a/c compressor? I've probably been using my a/c more in the past 6 months then I have over the whole time I've owned the car & I think my compressor is seizing up.

If I have the a/c turned on, when I accelerate from a dead stop, I get the most annoying noise from the engine bay & then it goes away after 5 seconds. When I come to a complete stop & start again, the same noise prevails.

Could the a/c unit be on its way out? It's almost as if the the compressor pulley is NOT turning & when I accelerate, the belt is just slipping over the compressor pulley (Hence the noise). Then after a couple seconds the pulley is freed up & the noise stops.

Any advice?

Marken aka "Lexlyf"

xsuperjoex

it could be the belt itself...you might want to get it changed....(does your AC work even if you have the noise??) and from what i think compressors don't get worse...either they work and they are fine or they just stop because there is no oil and freon in them.

lexlyf

While all the racket is going on, there is cold air blowing from the vents. The noise only comes when the a/c is on & I'm accelerating from a dead stop. Strange. If the belt were going bad....shouldn't the noise be constant or what am I overlooking?

Oh yeah..the belt was replaced last summer when I changed my radiator.

Thanks man.

xsuperjoex

if cold air is coming from your vents than there is nothing wrong with your compressor and the belt is trying to slip off of the pulley (result of overtighting or of a loose belt...probably to loose) you said you had it done last year was it at a dealer??

the reason why it does it while you are moving is because your belts move faster the faster you move! the reason why it goes on only while the AC is on is because when the compressor kicks on it puts tention on the belt because the pulley has to be forced to turn it's not a free spinning pulley like an alternator.

becareful you could lose that belt and it might rip on you in the middle of no where and if it's attached to your alternator then you're screwed you'd have about 10-15 minutes of driving power on just the battery

Hints that it fell off:
1. battery light comes on (keep an eye on this)
2. car feels extremely quicker (result of no belts)
3. ac doesn't work anymore (result of belt snapping)
4. headlights seem dimmer (unless you have HIDS ballasts will supply enough power until they die)

i hope you get it changed the right way and that the belt has enough tention (meaning tightness)..

I hope for your sake it doens't snap on you on the highway...(happened to me in my honda it really sux)

xsuperjoex

do me a favor get in your car and make the noise happen with your AC on. Do it 3 times (stop and go) then the 3rd time you do it get out as fast as you can open your hood and take a wiff...right near the belts if it smells like you just did a burnout then your belt is on the way out.

Rollin

When these compressors start to fail they usually start with a radial type whine the gets louder over time. Of course what's happening is the compressor starts to wear due to excessive internal clearances which start to fill the Receiver/dryer with contaminates. Which in turn increase pressure as a result of increasing restriction. Hence the belt slippage, if your getting any at all you'll be able to smell it coming thru the vent system. There is a pressure switch located on the side or at the rear of the compressor(depending on model) which will set off a Code if the restriction lasts longer than 5 seconds or so. It'll set off the AC light it'll flash and the compressor will kick off. I just replaced my compressor on my LS I went thru the same thing as you except mine seized. Upon tear down the first inner bearing wore out causing excessive clearance between the main shaft that actuates all five pistons causing them to eat away at the lobe (they use to move) itself until it locked up.
E-mail me if you want an internal description of one of these units..
Now there is a clutch bearing that can be replaced on the car. If this bearing is giving you trouble you will have mucho noise all the time. The best way to check this one is to release tension on the belt and spin the AC pulley by hand if it spins nice and freely its working, if it spins rough and feels like theres sand in it, its bad.
A word of advice find a used compressor if you can, one with known mileage on it. They last longer than a rebuilt one. And don't let them tell you a SC compressor won't work on your LS if this is the case or vice-versa. The only diff's are the connectors and the pulley/clutch assembly all of which will swap over from your old one otherwise the compressors themselves are the same dimensionally.
I found two compressors one for an LS and one for an SC. I pulled up in the LS and guess which one costs more? The LS....of course @ 365.00, I picked up the SC for 150.00 cause they said the "The Book says it won't work"..... I've got 37F at the vents on a 95F day Lol works for me.

Geoff

lexlyf

OK, Mo & I took a closer look & thought the belt was the cause of the noise. We replaced the belt & i didn't experience the noise during my morning drive.

When I drove the car in the afternoon, I heard the return of the squeeking noise. I again inspection the engine pulleys & noticed that the belt tension pulley is off a bit.

What I mean by this is that the way in which the actual belt sits on the tension pulley...looks as if half of the belt is sitting on the tension pulley & half of it is sitting off of the pulley close to the actual motor. Mo tells me that the tension pulley is probably bad.

Earlier today the noise got worse. Instead of happening after accerleration from a dead start (see initial post), the VERY LOUD squeek happens ALL THE TIME & it gets louder as I accelerate. I was able to get the car home & I inspected the engine bay while the motor was running & I could actual see the belt sliding back & forth on the tension pulley. As I revved the motor from under the hood, I could see that as the belt got closer to the engine bay, the noise occured & when it slid away from the engine, completely back on the pulley, the noise dissapeared.

Although I have never heard of a defective tension pulley, it safe to say that this is the reason for the noise. Does anyone have access to a used tension pulley for the 92 SC300 ?

I guess while its being replaced, Mo suggested to change the timing belt & radiator hoses (The bottom hose has a pin hole) since all that stuff has to come off.

Going fast is fun and all...but it irritates me to pieces when you can't even get your car to run the basics. Should I still replace the A/C compressor too?

Marken, aka Lexlyf

DevilDog

You hit it right on the nose! It is the belt tensioner pulley. When under a load it will make the noise when accelerating. Lexus did update that pulley. The old pulley wheel is made of plastic. The new pulley is made of metal. Go buy a NEW one! I have repaired several sc300s with the same problem. Another note, you don't have to remove the T-belt to replace the pulley. First remove the serpentine belt. Then remove the oil cap then the plastic cover that covers both the valve covers and the upper part of the t-belt area. Only has four allen screws. The pulley only has three bolts holding it on. Good luck!

lexlyf

So basically, this is the short cut method of replacing the belt tension pulley w/o removing the radiator?