Which part of my compressor blew up?

[avatar28]

Last night I started noticing an odd smell. Pull over and check and there is smoke coming from my serpentine belt area. This is not new, I've replaced the lower idler pulley 4 times because the bearings keep self-destructing. I babied it the six miles back home and took a better look. Smoke was coming from the center of AC pulley. There is also a loud rattle that has started, can't really tell where it's coming from. Even with the HVAC turned off, the face of the compressor pulley is turning slightly. Does that suggest that it may just be the bearing and not something much worse?

Here's a short video I made of the noise. HVAC is off but you can see the compressor still turning slowly.

What am I looking at to fix this? My car is obviously undriveable right now.

 

[pjtoledo]

most likely the AC clutch disk went bad. its held on by a nut in its center.
the disk does not have a solid steel connection between the center hub and the outer disk area, they are held together with rubber/poly material. if the rubber fails the disk is allowed to wobble, and likes to destroy nearby stuff.
taking the disk off does not effect anything else like belts or freon, it simply doesn't turn the compressor shaft if it isn't there.

Perry

 

[rubydist]

The a/c pulley runs on a bearing external to the a/c compressor. it engages the compressor by pulling in an electromagnet which causes the steel disk on the compressor shaft to engage the pulley, forcing the compressor to turn.

The symptoms you describe suggest that the pulley bearings are failing, causing the pulley to drag and the belt to slip. I had one actually disintegrate the belt in about a mile when the a/c pulley locked up.

If that is the case, the compressor may still be salvageable, if you can get the pulley and bearing off. In the case I had, I was not able to get the bearings off.

 

[avatar28]

most likely the AC clutch disk went bad. its held on by a nut in its center.
the disk does not have a solid steel connection between the center hub and the outer disk area, they are held together with rubber/poly material. if the rubber fails the disk is allowed to wobble, and likes to destroy nearby stuff.
taking the disk off does not effect anything else like belts or freon, it simply doesn't turn the compressor shaft if it isn't there.

Perry

So would I just need to replace the clutch in that case? Or is it possible to buy just the disk? If I decide that I'm not going to be able to afford to replace the compressor/clutch right now then I can just remove the disk and the pulley should free spin?

The a/c pulley runs on a bearing external to the a/c compressor. it engages the compressor by pulling in an electromagnet which causes the steel disk on the compressor shaft to engage the pulley, forcing the compressor to turn.

The symptoms you describe suggest that the pulley bearings are failing, causing the pulley to drag and the belt to slip. I had one actually disintegrate the belt in about a mile when the a/c pulley locked up.

If that is the case, the compressor may still be salvageable, if you can get the pulley and bearing off. In the case I had, I was not able to get the bearings off.

The belt doesn't seem to be slipping. The smoke was not coming from the belt but rather was coming from the center of the clutch as far as I could tell. Or the gap between the clutch and the pulley maybe. Is the pulley part of the clutch when I buy a clutch?

Okay, so given that the compressor was working up until this happened, does it seem reasonable that a clutch might fix it? Can I replace it without having to pull the entire compressor out? That seems like a MAJOR PITA undertaking (not to mention that I've got no way to evacuate the refrigerant from the system without just venting it to the atmosphere). Where is the best place to buy a clutch that will work correctly? I've heard a lot of them can't handle the higher revs of the SHO engine and fail prematurely.

Edit: if it looks like I'm going to need a compressor, I'm going to have to just bypass it for now. What's needed to do that? Shorter belt I know. Do I just go in and ask for a bypass belt at the auto parts store or what?

 

[luigisho]

They won't have any idea what size belt you need. They don't list bypass belts as far as I know. You have to dig into the search feature on the forum to see if someone already posted the correct length ...or get a piece of string, route the belt path without the ac compressor, measure the length and then go find a belt that way.

 

[avatar28]

They won't have any idea what size belt you need. They don't list bypass belts as far as I know. You have to dig into the search feature on the forum to see if someone already posted the correct length ...or get a piece of string, route the belt path without the ac compressor, measure the length and then go find a belt that way.

I've seen it listed somewhere. About 75 or 76 someodd inches (I know I need a little more exact measurement). The stores usually don't seem to be able to look up by size though, just model.

 

[luigisho]

Usually size and belt part number are related. You can find what you need if you have the rib count and length. Owners vary in how much info they have before they look for the correct part. Parts people vary in capability to locate what you need. For instance this belt is 6 rib and about 45ish inches http://shop.advanceautoparts.com/p/...lt-450k6/5064775-P?searchTerm=bely#fragment-2

 

[rubydist]

ok, so what you are saying now suggests that the gap in a/c clutch is too large, and the clutch is slipping, or that the compressor is binding and dragging. What happens in that case is that the pulley gets hot. There is a piece of rubber molded in there outside the bearing, so when the pulley gets hot the rubber starts to smoke/burn. I actually had one of the pulleys come apart when the compressor seized on me.

 

[pjtoledo]

the disk and clutch can be replaced without removing the compressor from the car. you can remove the DISK while leaving the belt on the pulley, fully tensioned. obviously not so for the pulley/innerpart of the clutch. the disk has a ring of holes around the center that enables you to hold it while the center nut is removed. the inside of the very center of the disk, where the nut is, is threaded so you can run a bolt in to press the disk off the shaft. I did not know about those threads, and chose to loosen the nut, put outward pressure on the disk, and carefully beat on the compressor shaft with a very small pein hammer. not to best method to use, but the compressor did last for several years after that.
you may have to get creative with your tools to hold the disk.
IF you have to then remove the clutch too, a custom set of snap ring plier tips is necessary.
I had a set with interchangeable tips, cut a couple of small allen wrenches down to size to make some long 90 degree tips for the big snap ring. still required some swearing and fananggling to get it off.
it has been more than a few years since I last did one, so the details are a bit fuzzy. hope I'm remembering the right car!!!!

its late, dark, and raining. no visual verification tonight. (sorry)



Perry

 

[avatar28]

the disk and clutch can be replaced without removing the compressor from the car. you can remove the DISK while leaving the belt on the pulley, fully tensioned. obviously not so for the pulley/innerpart of the clutch. the disk has a ring of holes around the center that enables you to hold it while the center nut is removed. the inside of the very center of the disk, where the nut is, is threaded so you can run a bolt in to press the disk off the shaft. I did not know about those threads, and chose to loosen the nut, put outward pressure on the disk, and carefully beat on the compressor shaft with a very small pein hammer. not to best method to use, but the compressor did last for several years after that.
you may have to get creative with your tools to hold the disk.
IF you have to then remove the clutch too, a custom set of snap ring plier tips is necessary.
I had a set with interchangeable tips, cut a couple of small allen wrenches down to size to make some long 90 degree tips for the big snap ring. still required some swearing and fananggling to get it off.
it has been more than a few years since I last did one, so the details are a bit fuzzy. hope I'm remembering the right car!!!!

its late, dark, and raining. no visual verification tonight. (sorry)



Perry

Thanks. Could just removing the disk be enough to get it running for now so that the pulley free spins until I get a clutch for it? Also best source for a clutch? I've heard that a lot of them tend to die prematurely due to the high RPMs our cars like to run.

 

[rubydist]

It depends on why it was slipping - I had one compressor that turned over fine when it was cold, or when I was turning it by hand, but if you ran it for a while, it would bind up and ruin the clutch. I destroyed two clutches before I figured out that my real problem was the compressor. My guess is that you have a similar situation, but its only a guess.

 

[pjtoledo]

the disk is what drives the compressor shaft, so if the disk is removed the shaft just sits there.
the pulley has a large bearing inside it, if that bearing is good the pulley/belt will spin with the engine, and the car can be driven.


the inner part of the pulley/bearing is bolted to the front of the compressor housing, not the shaft, just the housing. the inner part doesn't spin.
the electro-magnet coil (looks like a big doughnut) then resides inside the pulley, creates a magnetic force, and pulls the disk against the pulley. thus, driving the shaft.


Perry


actually its just a big retaining ring, not bolts, that holds the pulley on.

 

[avatar28]

It depends on why it was slipping - I had one compressor that turned over fine when it was cold, or when I was turning it by hand, but if you ran it for a while, it would bind up and ruin the clutch. I destroyed two clutches before I figured out that my real problem was the compressor. My guess is that you have a similar situation, but its only a guess.

Did you replace the compressor? What was the total price if you did? It seems like you have to replace pretty much the entire system outside of the piping.

 

[avatar28]

the disk has a ring of holes around the center that enables you to hold it while the center nut is removed.

What did you use to hold it? I tried a small allen wrench but it didn't grab and fell to oblivion somewhere I can't see.

the inside of the very center of the disk, where the nut is, is threaded so you can run a bolt in to press the disk off the shaft.

I'm sure you probably don't remember at this point but I was able to verify the threading on the outside rim of the center of the disk. Does anyone happen to know the size bolt I would need to use?

 

[rubydist]

Did you replace the compressor? What was the total price if you did? It seems like you have to replace pretty much the entire system outside of the piping.

yes, I replaced the compressor with a used one from my parts collection, so the price was pretty reasonable...

you are supposed to replace the orifice / expansion valve any time the compressor has an issue (because debris from the failing compressor can plug the orifice) but I did not and in this case I did not have a problem - I only replaced the compressor.

if you are paying someone to do it for you, you are looking at the cost of the compressor, the cost of the piece of tubing with the orifice, and the cost of an evacuation and fill w/ refrigerant.

in my case, I used about $15 of refrigerant, and I used my trusty $25 harbor freight vacuum thingy that runs on compressed air, so not too expensive. that vacuum thingy does not draw a tight vacuum, but it gets it low enough that it can be charged well enough to cool properly.

fyi, the evacuation does two vital things: first, it gets the air out of the system so that when you start to put in refrigerant its all refrigerant rather than a mix of air and refrigerant. second, it boils off the water that is inside the system, which is vital because water in there will freeze up the system. the reason they tell you to pull a vacuum on the system for 45 minutes is not to get every last 0.01" of vacuum, it is to allow the water to boil off.

 

[avatar28]

Thanks. You don't know what size bolt it is to get the the clutch disk off do you? And how do you hold the disk still to get the nut off the center?

 

[rubydist]

there are holes around the clutch that there is a tool to fit into to hold it. you can fit some small bolts in two of those holes and put a pry bar across them, or something similar to hold the thing while you pull off the nut. I don't recall the nut size, but its a common metric size.

 

[avatar28]

Okay. Got my replacement clutch, only took about a week. It appears to be the correct SHO, not SLO, one. Now I have NO clue how to actually swap that sucker out. It came with a little packet of parts, a Nippondenso clutch shim kit with shaft keys. Is there a writeup anywhere that tells which part is which and where they go (and more importantly, how to actually do the replacement)? I'm still hopeful that I can manage to pull it off without removing the entire compressor.

 

[pjtoledo]

pics of AC clutch parts

some pics of an old junk compressor with clutch
Perry

oops, that didn't work right

 

[avatar28]

Here are a couple more pictures of what I've got. Looks like I need to replace the coil too? I'm assuming all that wire I'm seeing is the coil but the dust cover for it is gone.

The disk.


The pulley.


What's left of the clutch on the car.



The replacement clutch came with a packet of parts. I'm not sure what several of them are for (like the shaft keys, the two rings for the coil, etc).