A/C compressor (clutch?) failure

Driving home yesterday in my C900, I noticed the A/C - which is usually surprisingly effective - was cooling somewhat intermittently. I figured since it was a very hot, sunny day (ambient ~90F) it was just having trouble keeping up. Then I noticed a strange smell, so I decided to pull over and have a look. When I stopped there was a curl of smoke emanating from under the hood, which clearly did not bode well.

Popped the hood and saw the source of the smoke:

This made me think that the clutch on the compressor might be the culprit, and sure enough when I engaged it I could see that it was barely spinning the compressor. Kept it off and drove home without incident or reoccurrence of the smell. The belt, which I pulled off this morning, looked fine and showed no signs of heat or friction damage. That said, I've now read that there is a bearing in there somewhere that's prone to failure, so that could be the problem. Spinning the pulley with the belt off seems OK and without any horrible grinding or roughness.

It seems to me that the clutch is going to have to come off in any case, and if that happens I should probably replace the troublesome bearing as well, but then what? I can't find a source for the clutch alone. Are they rebuildable? Are there generic units that I can fit? Or is it just suck it up and buy a rebuilt compressor (which I'd rather not do if the clutch is the problem, as it's real money and I'm not sure how much I trust rebuilders these days, plus I'd have to open the system and recharge it)?

Does that vehicle have an idler arm for that belt?  If so, that may be the failure point.

Sounds like the clutch is just going out. Most of the time you end up replacing the compressor, as the clutch parts can be as much as the whole compressor.

There is a manually-tensioned idler, but I replaced that pulley when I had the whole front end of the engine apart last year. It's definitely the compressor that's the problem.

As to replacing the whole compressor, I will if I have to, but being that this is a 30 year old car from a dead brand with parts prices to match, I'd rather not if I can avoid it. But I have to see if the clutch parts are even available before I start making financial decisions.

Update: I got the clutch off. There are several issues present that I will discuss, but the primary problem is that the pulley bearing is failing - not locked up, but stiff, and there's grease everywhere on the inside of the pulley and the outside of the electromagnet. I suspect that the smoke was from the grease burning between those two, plus the bearing itself. Thankfully, nothing is melted, and the markings on the bearing are perfectly clear, so sourcing a replacement shouldn't be too problematic. The burned grease cleaned up easily with a Scotchbrite pad and some brake clean. I'm pretty confident that the heat didn't damage the compressor, as I can see the bearing on the shaft and it looks perfect.

The other issues are 1) that the clutch plates look pretty ugly, and 2) the insulation (?) on the magnet is failing, probably due to a combination of age and heat. The questions are 1) how good do they have to be to engage consistently, and 2) does it matter, and if it does, what can I do about it? I'll put pictures up in a bit if anyone wants a visual reference.

Ideally, I'd like to replace the whole clutch and call it done, but as noted I haven't found a source as yet.

Heat and impatience wins again. Ordered the bearing. Cleaned everything, ran the DA lightly over the clamping surfaces with a fine grit disc. When it shows up, everything goes back together and I hope it works.

Follow-up question on the insulating material on the electromagnet. This is what it looked like when I pulled it:

And this is what it looked like after I cleaned off the loose stuff:

Do the exposed coils in there matter? If they do need to be covered, what's the preferred material? Can I just put a layer of RTV on there, or does it need something like epoxy? I've got a few days before the bearing shows up, so drying time shouldn't be an issue.

You probably need to ohm the coil and compare it to spec. My guess is the coil fried and wasn't pulling the disk in hard enough to spin the compressor. 

The Googles says it should be 5 ohms. 

81cpcamaro said:

... Most of the time you end up replacing the compressor, as the clutch parts can be as much as the whole compressor.

This is exactly what I found when the a/c clutch failed on the ‘06 Civic last summer.  A clutch from Honda was about $250, and I would have had to buy extra long snap ring pliers that were substantial enough for the job.  There were Chinesium clutch replacement alternatives on the bay of e’s for about $30, but nothing in between.  A brand new Denso compressor with clutch was also $250 from R/A so that was what I went with instead.

You need a new clutch.

The coil shows 3.6 ohms. I can't find the manufacturer spec, but that's pretty close to the 5 ohms mentioned, and certainly not shorted.

I could replace the compressor, but it would be rebuilt and of unknown quality, and it would cost actual money. This being a very cheap project car that I would like to remain very cheap, I think it's getting a $30 OE bearing and a good clean, and it damn well better be happy with that.

Anecdotal ramble here. I had the same problem on my Toyota Matrix. Replaced the clutch. Properly. It lasted all of three months, then I had to buy a new compressor anyway.

I hope you fare better, but I felt decidedly like a tool.

In reply to Streetwiseguy :

Perhaps, but I can't buy a new clutch, at least not from any supplier I can find. Hence my attempts to make do with what's available.

In reply to wheelsmithy (Joe-with-an-L) (Forum Supporter) :

Well, if the bearing lasts three months it will be almost October, and I can deal with it over the winter. But I would prefer if it lasted a bit longer.

Arrggg!

My experience with AC compressors is that the first one will last for 30 years, but whether new or rebuilt, the replacement parts will be dead in two years. My truck needs it's fourth one. Both replacements were new AC Delco.

I hope you're successful in saving yours with a clutch repair.

The entire system is getting replaced on my Ralliart wagon this week, for about 40% of the value of the car. 

In reply to Floating Doc (Forum Supporter) :

I tend to think of all work on this car in terms of percentage of purchase price - value is very difficult to determine accurately on a rusty 30-year old Saab, but it's low. The bearing alone will be approaching 5% of purchase price. I dread to think what the compressor would be.

So far I've probably tripled my initial investment just getting things sorted, and not one penny of that has been labor. I'd rather not balloon that figure further.

Was driving my 2015 Fiesta ST and after hearing a noise from under the hood turned around went back home. Open the hood with engine idling didn't hear noise. Had my wife sit in drivers seat a rev engine a couple times. There was a loud grinding sound and the front half of the A/C compressor clutch shot out from under the car just missing my foot and rolled about ten feet in front of car. Evidently the A/C compressor seized up shearing the shaft. Car has low mileage but had timed out of warranty. Dealership charged me over $800 to fix. Call to Ford Corporate Customer Service  was useless. 

A brand new chineseum compressor is probably available for the SAAB. When the actual compressing part fails the new unit will have a non serviceable clutch. I have seen this repeatedly, and it is the reason that very few clutch parts are available any more. Be glad you still have an old one.

02Pilot said:

In reply to wheelsmithy (Joe-with-an-L) (Forum Supporter) :

Well, if the bearing lasts three months it will be almost October, and I can deal with it over the winter. But I would prefer if it lasted a bit longer.

Mine rattled like berk, and drove me crazy. This may have very little to do with your actual situation.

Floating Doc (Forum Supporter) said:

Arrggg!

My experience with AC compressors is that the first one will last for 30 years, but whether new or rebuilt, the replacement parts will be dead in two years. My truck needs it's fourth one. Both replacements were new AC Delco.

I hope you're successful in saving yours with a clutch repair.

The entire system is getting replaced on my Ralliart wagon this week, for about 40% of the value of the car. 

 

Don't just replace the compressor. 

All systems, at a minimum, need the receiver drier, orifice/expansion valve to be replaced and the rest of the system flushed to get all the old compressor fragments out. There are also several systems that need the condenser coil replaced as well due to them being impossible to flush. If you don't it eats the new compressor fairly quickly. 

Update. Bearing arrived this morning. I had everything ready to go, pressed it in (after 30 minutes in the freezer), and slapped everything together. Pulley and compressor turn nice and freely, everything seemed good....

Until I tried to turn it on. Nothing. However, I immediately began to suspect something else was wrong, as the electric radiator fan didn't come on either. Started checking and I had no voltage at the compressor. Applied 12v to the compressor and the clutch worked perfectly, so at least I knew that that problem was solved. Ran through the wiring diagram piece by piece until I found the problem (I hope) - jumping the low pressure switch kicked everything on, but no apparent cooling. Cleaned up the sight glass - which was so dirty I had trouble locating it - and saw bubbles. OK, so it needs to be charged, but the real question is: how was it working fine until the bearing failure prevented the compressor from spinning freely, and now suddenly it's low on refrigerant?

I really hate that I'm going to have to spend more money sorting this out, either buying a set of gauges or taking it somewhere. I'm seriously tempted to buy one of those cans of R134 with a gauge on it from Walmart and just half-ass the thing.

EDIT: Oh, yeah, I also discovered when I went to reassemble it that the magnet was indexed wrong. It uses a circlip and a locating pin to keep it in place. I didn't pay much attention to this when I took it apart, but going back together I realized that the wire wouldn't reach if it were indexed correctly, so it much have been out of place before. I extended the wire.

In reply to Toyman01 (Moderately Supportive Dude) :

Watched a Car Wizard video yesterday that said exactly the same.

Car Wizard.

Update again. Grabbed a can of R134 (the system was converted back in the 90s, according to the sticker on the fender) with a gauge and stuck it on the low side port. Sure enough, low - ~20psi, if the "gauge" is to be believed (precise and confidence-inspiring it is not). Jumped the low pressure switch and put in some refrigerant. Checked - still low. Put in some more. OK, now in the green (~30-50psi or so - I was at ~35psi). Plugged in the low pressure switch and the compressor and fans engaged, confirming that the issue was low pressure. However, a problem and questions remain.

The problem is that it's not making cold air. The clutch engages, the compressor runs (I turned it by hand before I reassembled and it seemed nice and smooth), but it blows warm. Still seeing bubbles in the sight glass, but obviously the pressure is high enough not to trip the switch and cut power to the compressor clutch. Do I keep adding refrigerant until the bubbles go away? Is this a byproduct of being a converted system, i.e., should I be looking for different pressures than in a normal R134 system (doesn't make sense to me, but what do I know)?

And how was the system doing so well before? How does a pulley bearing failure relate to a loss of refrigerant (I can't think of anything)? There's zero overt sign of any issue except for the bubbles in the sight glass and the warm air blowing out of the vents. I'm sure the correct solution is to get proper gauges and a vacuum pump, evacuate the system, and refill by weight, but bearing in mind that I'm already approaching 10% of the purchase price of the car with a bearing and a big can of R134, you can imagine I'm not looking to spend a lot more money here. I also have little to lose.

EDIT: Doing some reading and I see a few things repeated. According to some, bubbles in the sight glass seem to be the norm in R134 systems, though how many is unclear; I'm seeing nothing but bubbles. Some suggest spraying the condenser with water during the charging process to lower the temps and help to get a full charge into the system, especially if ambient is high (which it was while I was working).

The plan for tomorrow is to get at it in the morning when it's cooler, see where the low side reads, try spraying some water on the condenser, and see where that lands me. I have a feeling the system is still low, but I still can't understand why, given no signs of leakage. That said, we'll see where things stand in the morning - if the low pressure switch trips out again I'll have to look again.

SECOND EDIT: I may be more of an idiot than I already suspected. I was referring above to what were actually the static readings (come to find out) with the system off. Based on the pressure-temperature relationship charts I've found, I should be looking for a much higher static pressure as a starting point. More to come tomorrow as I (probably badly) educate myself on automotive A/C systems.

In reply to 02Pilot :

Freon leaks often leave no visible traces. The loss happening with clutch failure might be failing compressor shaft seal due to vibration and heat during the failure. If so you will probably have a permanent leak now.