I was at work and went to move my Vette closer to the bldg, about a hundred yards, and suddenly I see smoke coming from under the hood. I open up and it's coming from the compressor. I cautiously touched the front of the clutch pack and you could've fried eggs on it. Prior to this the engine had been off for two hours.(After seeming to operate normally) I'm thinking the compressor is going bad. It's only about two or three years old, but I remember it wouldn't turn by hand when new. What do you guys think? I did a search and found something about the relay being bad, but I don't think that would cause it to get that hot, that quick. When I tested it just now, things seemed to be operating normally.(???)

After a bit of looking, I noticed the compressor throws oil when the A/C is OFF. It seems to be doing it a bit as oil is thrown on the underside of the hood, and some surrounding areas as if it's been thrown from the pulley. I'm thinking the compressor may be on it's way out. The place I got the compressor from is going to stand behind it, but I want to make sure it's the compressor before I swap it out.

Btw, anyone know where the orifice tube is located in the 1988 system.

As always, any help you can offer is, "mucho-appreciado."

it sounds like the seals are shot. You can get new seals and repair accordingly.

Do you have the nippondenso or harrison compressor?

The orifice tube is mounted vertically inside the line in front of the evaporator box. I'm on my phone now but I'll give you a more in depth answer later.

I had a better link for the picture, but it went away. This should show up ok

Joel

http://www.parts123.com/parts123/yb.d ... 50g~Z5Z5Z5~Z5Z5Z50000050F

OK, Bob...a brief check looks like 88-91 compressors should all be the denso version.

So.....

You have to determine what was smoking on the front.

Was it the compressor locked up causing the belt to slip and cause heat/friction/smoke?

or

Did the coil overheat and cause the clutch to fry the rubber dampener on the inside?

In my case, the coil overheated frying the clutch. Reason? I don't know. Bad coil? Bad blower control module? Dunno.

Since you stated it wouldn't turn by hand when new that's a problem. Can you turn it by hand now? Have you verified any pressures while running? It's strange that it runs fine now but was smoking before?

If you see signs of fresh oil, it's more than likely leaking at the shaft seal. Not a terrible job to replace, but if you are getting a new compressor then it's not necessary.

By checking the orifice tube, you may see signs of any crap in the system caused by the compressor going bad. If the compressor exploded, you really need to replace the compressor, orifice tube, accumulator/drier, and you should replace the condenser, but might get by with a good system flush. Then you need to vacuum and fill it. Not a bad idea to replace the o-rings while you're at it since you'll be that far in.

Joel's link has a good breakdown of parts:



I have photos on my other camera if you need more, I just haven't uploaded them yet.

Matthew

Thanks for the replies.

The condenser is a Denso, I should've said so in the 1st place.

The rubber dampener may have been getting fried as the smoke from underhood had a bit of a rubber smell.

I haven't tried turning it by hand now, I'll hafta take the belt loose and try it tomorrow.

It's odd, but today when I tried turning it on again, it seemed to operate normally, getting cold frosty lines underhood.

I just checked, the compressor WILL turn by hand now.

When you say you can turn the compressor by hand, are you sure the compressor is turning or just the clutch? In order to turn the compressor, the ignition switch must be on and then AC set to on position. This locks the clutch to the compressor.
But regardless, if there is compressor oil on the underside of the hood there is a seal that has failed. Usually this is the shaft seal behind the clutch.

Was this a new replacement compressor or a rebuild?

Joel

Quote:

You bring up a good point. I'll go out again today and see if it's the clutch or the pulley that turns by hand.
This compressor was a new aftermarket replacement when I got it.

You can also use a wrench to turn the 10mm screw at the center of the compressor to see if it turns.

Fwiw, the compressor is off, and I'm s'posed to pick up the new one tomorrow (tues)

Don't forget orifice tube, accumulator/drier, oil, freon, and at minimum blow out the condenser and evaporator with compressed air.

Thanks for the reminder...
Orifice tube is to be picked up. The accumulator was new 2-3 yrs ago. I plan on the oil,and of course the 134a as well. I'll go ahead and blow out the condenser and evap as well as per your suggestion.
Thanks again.

Anytime the accumulator is open for more than a couple hours the dessicant will absorb moisture from the air. I would replace it. I ordered a gm replacement from rock auto for about 20 bucks.

Vacuum out the system before the recharge. Blowing it out will just introduce a lot of moisture, unless you have dry nitrogen of course.

Quote:

I neglected to mention vacuum....a necessary step, thanks fora pointing that out. I recommended blowing it out in case the compressor was damaged and introduced any debris in to the system. There are specific cleaners for that purpose, but using compressed air won't hurt as an extra precaution.

If your orifice tube has metal bits in it or is extremely black, the compressor probably blew up inside and it's necessary to at minimum clean the system or better yet replace the condenser.

I'm gambling it didn't blow up the compressor. Just because of the feel of it and knowing how it was generally working at the time I removed it. The orifice valve was somewhat dirty, but I'm pretty sure it was partly because I didn't change it last time. That was because of not knowing I needed to. But now it's changed, the compressor is changed, and I'm vacuuming it out as I write this. Let's all pray to ZORA, the corvette god, there aren't any leaks.
And for real, I'm praying to the Son of God for the same reason.
In the immortal words of Arnold,

I'LL BE BACK....

Good luck!

Joel

Any updates? How did it hold vacuum? Any leaks?

for those who like to do this at home . if you have a compressor , harbor freight has a neat little e vac unit for 16 bucks and it works like a champ.

Quote:

I'm not sure it's holding vacuum. I've let the pump run for a couple hours, disconnected it then shut it off. A few hours later I came back to it and started up the pump and then reconnected it. I could hear the pump pulling down the vacuum and the pump exhaust shows the vapor coming out each time. It makes me wonder if the system is built to hold pressure not vacuum, or do I now have to check the 3-4 connections I messed with for leaks, or is it a bad pump from the git-go?

I assume you have a set of gages hooked up to read the vacuum? Pump should pull vacuum down to 29 inches and system should hold this vacuum. If system will not hold this vacuum, there is a leak somewhere.
Pump and gage set should remain hooked to the car after the evacuation is complete. Just close off the valve from the pump and shut off the pump.

The system is designed to hold pressure as well as vacuum. And there is a lot more pressure than vacuum when the AC is running. The main purpose of the evacuation is to remove moisture and trapped air. But, it also shows if there is a major leak.

Joel

Quote:

Yep, and of you solder 2 pieces of copper into a mason jar lid, you have a vacuum brake bleeder setup.

The HF vac will pull 21 inches @ 75 psi. air pressure.

Bob - what Joel said. You need to use a set of gauges when you do the vacuum. One to the high side, one to the low side, the pump in the middle. Once you vacuum it down to 29, close the connection in the middle and turn off the pump. Let it sit for at least 30 mins and see if the gauge moves.

Once the a/c is running, the pressure inside the line will get over 400 psi before the high pressure cut out switch goes off.

An interesting thing with my conversion - I pinched an o-ring on the compressor manifold. Held vacuum perfectly. But after pressurizing it, began leaking and pushing dye out. Replaced that and no more problems.

Also make sure your pump connection / high and low connections are good. Sometimes those quick adapters aren't screwed on enough and leak there.

If you can't get a good vacuum, you might consider taking it to a shop that has the actual machine. Some shops have recharge specials for like $59 or something...well worth it in my opinion. It's cheaper than buying a good set of gauges and you will get the correct vacuum and refrigerant fill.

Matthew

I wasn't able to mess w/ this today as I had to go to a family wedding. But after thinking this thru, my most likely spot to begin looking is the compressor. Either at the manifold on top, or it's leaking thru the front seal behind the clutch. I think tomorrow I'll try to pressurize the system and put some soapy water on the connections I messed with to see what happens.

Update...

I'm too cheap to pay the $$ for a set of guages that'll tell me I have a vacuum leak when it's been established that I have a vacuum leak, so I sacrificed a can of refrigerant and checked the fittings I mesed with. Using the soapy water method I found the High side fitting to be bubbling. The valve leaks a bit, but the O-ring in the 134-a adapter is shot so I'm gonna go get one, reinstall the adapter, and see if it holds.

More to come.........

I can understand not wanting to buy gauges...I borrowed some from my neighbor. But they are very helpful in making sure you have the correct refrigerant charge and for testing the system pressure once it's runnning.

Hopefully the high side fitting is the culprit.

Quote:

I got a new hi-side fitting as the o-rings were more expensive and only available by the hundreds. I hit it with soapy water and no bubbles, so I went ahead and charged it up. the outdoor temp was 77 so I cross-referenced the temp to the pressure on the can and went that way. I'll let it sit a couple days and check it to see if the system holds or not. If so, all's well, if not I'm buyin' guages and fighting it out.

Post #400. I guess there's a little post-ho in all of us.

Quote:

Fixed it for ya!