I have a 93 LT1. Last night I did a quick full throttle run for maybe 15 sec.
I had the A/C on and about 3/4 through the run the blower fan cut off.

When I got off the throttle the blower fan came back on but the air was not cool.

I turned the thermostat down and it startred getting cool again and I thought everything was alright--until I stopped at a light.

Smoke was coming out from under the hood!!

I pulled over and popped the hood thinking a hose blew but smoke was pouring out of the front of the compressor with the engine shut down.

There was also black residue below the pulley area. The belt was still on and intact.

I turned off the A/C and drove home,about 2 mi. and shut it down.

I got up the next day and when I opened the hood I could see a little more black resdue. I'm not sure if it's from the clutches or belt but I think it's the clutches because it still smelled burnt.

I cranked it up with the A/C off to make sure the compressor wasn't locked up and it wasn't.

I then tried the A/C and it worked and everything seemed normal and cold. Any Ideas what happened and why?

Thanks Herb
p.s the rpm during the run was about 6000

 

If everything seems to be back to normal now, my guess is that your belt was slipping at 6000rpm. At a minimum, I would throw on an AC gauge and check the high and low side pressures. If you are low on freon, and the clutch was "cycling" at high rpm's, that could definately cause slipping during clutch engagement.

 

Sounds like the clutch coil is melted.

At full throttle the ECM will disengage the Compressor.

If you decide to replace the clutch coil, to remove it requires the refrigerant be removed because the AC hose is in the way preventing the removal of the Clutch coil.

Some people have carefully bent the hose and changed the Clutch coil without discharging the system.

Item #6 in the picture is what is probably melted. Even though it's working now, I'd replace it.

 

Thanks guys for the info.

Where did you get the blow up of the parts?

 

Same symptoms on an 89 that sat for some time. Heavy smoke coming from the clutch, even managed to stall out the engine. Smelled like burned brakes.

The wear on the clutch was impressive. The coil actually melted itself to the housing inside the pulley. We physically couldn't turn the pulley with the belt off using a giant pair of grips.

Got the first spring clip off with a bit of destruction to the bearing cover that it had partially implanted itself into, but the larger problem was that the second spring clip that holds the electomagnet is only accessable once the pulley is removed... SIGH!

Finally decided to dremel off the pulley by grinding the 6 bridge points on the front. We also used some tranny fluid to try to penetrate the mess.

Turns out after grinding about half the points in an effort to remove the hub portion to get to the clip and slide both magnet and pulley off together, the tranny fluid did it's trick and they seperated like they're supposed to.

The compressor seems to turn freely, more easily when warm then cold as to be expected. Hopefully the clutch was the problem in itself and we don't have a clutch eating problem with the compressor. We suspect that the magnet coils had become compromised and that it was expanding on itself, and literally welded itself to the pulley.

Time will tell. System had just been recharged with a new condenser so hopefully we don't need to do a purge again.

 

I had the same symptoms on my '93 at one point, but the problem turned out to be the rubber part of the #7 part in the above picture (front clutch plate). Easy replacement, unbolt the one bolt in the center and the front plate comes right off. Just make sure you don't lose the shims on the inside.

I would check that part. When the rubber gets hot, it starts melt (thats what creates the smoke) and only the outer ring will spin, which means the compressor isn't spinning. Then when its cooled down again, it doesn't slip anymore. Although after a few cycles of that, pretty soon it wont work even when cooled down.

 

I suspect this to be my problem. Does anyone know where you can buy the parts individually without buying a whole new clutch?

 

I just had a similar thing happen to my '93 LT1. I bought a new AC Delco Clutch assembly (15-4623) from Auto Parts Tomorrow.com. It cost $266 for a brand new part. I purschased a rebuilt unit for $110 but took it back after discovering a Chinese bearing.

I had burnt black goo thrown around but the belt was 100% intact. The bearing supporting my AC pulley failed and threw its grease (110K and the car sat for a long time ) ). That caused my smoke; fortunately no compressor damage. To remove the clutch just unbolt the clutch, remove the serp belt then get ready to make a slight adjustment. Carefully bend the outer most AC tube in order to fit the pulley remover. It isn't much. Maybe 5mm. No need to drain the system. Then use any pulley remover that you can rent for free at AutoZone etc. Installation is a breeze-- reverse order.

 

Depending on your gas charge you may have experienced the a/c compressor clutch slipping 7 and 3 on the diagram posted by someone.

When you had the a/c on perhaps low fan speed and high rpm, the compressor may have had a bit too much liquid refrigerant.
Now we all know from physics liquid does not compress.... hence the clutch will slip or the serpentine belt or both

I have had this happen in winter with a/c to demist and a opportunity arose to embarrass a ricer, well i was embarrassed when i had to pull over to investigate the smoke ....after i blew his doors of first of course
There was a lot of material that came from the a/c clutch, it ran ok for some months then i replaced the clutch it got worse with time.