crammit442

'97 4runner, auto, 4wd, SR5, 3.4L. I headed out Friday on 1.5 hour ride when I left, the A/C was COLD as a always. When I got close to my destination, I noticed it was NOT quite as cool. On the way home it became obvious that the A/C was no longer cooling. It may have been a bad idea, but I stopped by O'Reilly and got a DIY can of 134. It didn't make any difference and the system didn't wasn't to take it in. After getting home and running the truck with A/C running wide open I watched the compressor. What I found was that the A/C clutch would occasionally engage, but with all sorts of wailing and gnashing of teeth. It was NOT rotating freely and the belt would actually start to smoke. When this happened it would only last a few seconds and then the clutch would disengage and things were normal until the clutch engaged again. When engaged, the pulley WOULD rotate, but not smoothly. My question is this. Does it ever happen that only the clutch will fail w/o the compressor failing or is it more likely that the compressor is dying and the belt just doesn't have the torque to turn a compressor that's on it's way out? I'm anything but an A/C expert, but I do have access to vacuum pumps and any tools to do the mechanical work. At 306,000 miles it's hard to justify spending big money on a repair. I've had very good luck with buying used OE parts from eBay. Most of the sellers show the vehicle with VIN and odometer #'s. Most parts have come with lengthy warranties. I know there are REAL experts here. Assuming I have competent help, is there a reason NOT to work on this myself. As it's NOT working now, I'm not sure I have much to lose. I have the ability to recover refrigerant as well. Thanks in advance!

Charles

wyoming9

iTrader: (1)

Does the clutch spin free with the AC off??

These clutches are quite simple they pull in or they don`t.

Sounds like your compressor has died the final death going by what you have stated.

Put your gauges on and see what is happening

crammit442

Yep. Spins free when A/C is off. When AC is on the clutch pulls in, but doesn't spin freely. For lack of a better description, it spins but in short pieces of rotations. I'm assuming it senses the load because after turning a few times (with big resistance) it disengages automatically. I'm also afraid it's the compressor, but I've read accounts of clutch/clutch bearing failures and even old or cheap belts smoking on the pulley instead of turning it. One thing that could possibly help with the diagnosis is that for the brief period of time the clutch engages before it releases, the vent temp in the car drops noticeably for a short time. I'm sure I'm probably whistling through the graveyard, but it sure would be more fun to change the clutch/bearing than the compressor and everything that comes with that. Either way, I'll be doing the work. It's hard to justify almost 1k on the AC on a 4runner that's 19 years old with 306,000 miles on it. I really appreciate the help and hope someone thinks there might be reason to think it's not the compressor. Thanks very much.
Charles

millball

There is no reason to think it's not the compressor.

It is clear that it's not the clutch, when the clutch is able to engage strongly enough to smoke the drive belt.

I assume that you're sharp enough to know whether the drive belt is tensioned appropriately??

Put the guages on it like Wyoming9 said.

millball

Duplcate

crammit442

I'm not the sharpest spoon in the drawer, but yes, the belt is tight. It is however, the original at 306,000 miles. I'd think the belt is not likely the problem. I suppose as a last ditch hail Mary I could remove the belt, bypass the AC switch to engage the clutch and see what it feels like by hand. I'm sure you're right, I'm just hoping against hope that it might prove to be something easier to repair.
Thanks lots for your help.
Charles

wyoming9

iTrader: (1)

Know way to tell but hands on work Compressor might be fine .doubtful but you might get lucky

It could be any one of several problems causing a over pressure problem which opens the AC clutch circuit.

Bad bearings in the Compressor causing a low pressure problem

Just no way to without hands on.

crammit442

So, does my idea in my previous post sound like a feasible way to get a hands on feel for what might be going on before committing to swapping in a new compressor? Worst case scenario, it's the compressor and I've already gotten things partially disassembled. Thanks much for the input.
Charles

millball

Sure, all it takes is to remove, or slack, the drive belt and then a jumper from battery positive to the clutch magnet wire and you should be able to manipulate the compressor by hand.

You're just grasping at straws, you know what you're gonna find.

wyoming9

iTrader: (1)

I know what I would find but some one might have better luck then me !!

It would not take much

crammit442

That's not really what I'd like to hear, but in a sad, dry humor kind of way, what you said is quite funny. I'm actually sitting here laughing as I write this. I have a peculiar dry sense of humor as well. Nicely done!

Charles

crammit442

OK. The plot thickens. On the way home from work I decided to turrn the compressor on and see what would happen. It didn't sound all that wonderful, but I got cold air for 3 or 4 minutes. I don't know for sure, but I wouldn't think I'd get ANYTHING if the compressor was locked up. I'm hoping this MIGHT mean it's the clutch instead. What's the thinking here? Thanks!
Charles

wyoming9

iTrader: (1)

Until you put manifold gauges on your just guessing!!!!

You have a pressure problem for some reason .

From your statements the AC amplifier (computer) cuts the voltage to the compressor or the belt would just keep slipping till it burned through and broke

Hard to trouble shoot long distance . Like trying to tell a nervous Father how to do a C section on the phone and save both Mother and Child

by all means if it will make you feel better change the AC clutch.

millball

Well, was it the compressor????

Please tell us.

crammit442

I apologize for not getting back to this sooner. I DID go ahead and get a good warrantied used Denso and clutch from eBay. I put it off as long as possible. Interestingly, over the last few weeks it's been cooling again, albeit with a low growl. Swapped out my 306,000 mile belt with a new one. Cools, but still growls. Decided to go ahead and do the clutch last night. Got the front off no problem. Got the belted part (with the bearing) off with more trouble (retaining ring). Spent hours with mirror and a hundred different retaining ring pliers on the magnet to no avail. Had to quit at 3:00 am. Reassembled. No more growl, smooth as silk. When the compressor switch is turned on I get the normal electronic click and the tach floats about 200 R's and levels off just right. The only really awesome thing is that while I have cold,quiet air, the clutch is actually engaged ALL THE TIME. the only thing I can surmise is that I had a clutch bearing going and in an awesome cooincedence, the wiring to the magnet has shorted closed so that the clutch stays on now. With my spate of good luck, I'm driving to Georgia tonight to buy lottery tickets. I guess I'm going be to be in there again and staying there until I manage to get the magnet retaining ring off and swap the magnet. What do you think?

Charles

millball

You do know that you have to shim or adjust AC clutches when you change them??

More than likely you put the clutch together tight, so that it cannot physically disengage.

Its easy to tell with the belt off and no power to the magnet.

It's probably not an electrical fault, if it worked before you touched it.

crammit442

I've about had enough of you coming in here and telling me how to do things the correct way. All kidding aside, that makes sense and I'd be willing to bet you're right. I assume since you knew that, you probably know the shimmed spec? I hate to give you more ammo for having fun with me, but without having it in my hands I'm guessing I'm supposed to shim before I install the final female splined piece. Thanks for the help and I really do appreciate your most excellent dry sense of humor. You sound EXACTLY like I do in arenas in which I'm the experienced one. Thanks much!
Charles

millball

I just changed a clutch on my Ford escort today.

It uses a Denso compressor similar to the ones in my Toyotas.

The Air gap spec was about .4mm to about .8mm max.

Yes, the shim/s go inside the female spline, to space it out away from the pulley itself.

I stoned a thick washer shim down until the gap was about .4mm, as the gap will wear wider while in service.

I assume the Toyota specs will be found to be similar, but I'm not sure.

You can google it. I have some stuff to do now before it gets hellishly hot here in sunny AZ.

All the Best!!

crammit442

I appreciate it. I'll post what happens.
Charles

crammit442

Sorry for it taking so long to get back with my results. You were correct. It needed probably .010 ish shimming. Everything works perfect and blows ice cold air. Thanks for the help.
​​​​​​​Charles