A/C Compressor Related Fire (1999 4.3L Vortec w/4wd)
 

Howdy!

Mostly lurk and have found a wealth of info here; hoping someone can help me with a problem. Searching has helped but I am left with some questions.

Situation: Driving down the hwy with the A/C on, I noticed the air warmed up significantly. A minute or so later I noticed embers flying in my drivers side mirror. Immediately pulled over, turned Blazer off, and opened the hood. Turns out the embers were coming from the front of the A/C pulley/clutch and the clutch plate itself was glowing red-hot. Luckily I was able to get the fire out without any major damage to other parts. We did start the truck (w/ A/C off) after letting it cool down a while but it made a bad grinding sound so immediately shut it off again. Just had the truck towed home and is sitting in the driveway.

What I found suggest the problem might be: the compressor pulley bearing, the A/C clutch, or the compressor itself. I plan on taking the belt off tonight and seeing if the pulley spins freely and go from there. How can I check the compressor to see if it is good or not? I'd like to figure out exactly what the problem is before putting unnecessary work and parts into it (cough, compressor, accumulator, orifice tube, etc. cough). Also, I'm trying to avoid removing the compressor if possible so I don't have to mess with recapturing refrigerant, etc...

If anyone could offer info/advice on how to diagnose the problem it would be greatly appreciated.

1 of 2 things happened:

1) The clutch wore out to the point of slipping continuously and got that hot.

2) The compressor came apart and locked up and that made the clutch start slipping. However, the low pressure switch should have dropped out the clutch if the compressor came to a halt abruptly.

You can start the way I did when the compressor ate itself and change a clutch first with the POS rental tools from the part house and go from there. Then test and see what the condition of the compressor is. If it doesn't turn, or turns and still makes noise, then you will be doing compressor, accumulator, orifice tube, chemical cleaning of the evap and condenser. I changed the hoses as well since they have a muffler in the discharge hose that is tough to clean.

I took the belt and the clutch off last night. Didn't have the retainer ring pliers to remove the pulley but will pull that later today. The pulley/bearing does not turn easily and feels/sounds like it's grinding. Could the excessive heat on the clutch (which was glowing red-hot and on fire) have fried the bearing? Once I get the pulley off is there a way to check the compressor without opening the system or putting new pulley/bearing/clutch on? I did try turning the compressor shaft by hand and it turned about 1/4 turn but was not easy.

Leaky 4.3: In no.2, what exactly do you mean "the low pressure switch should have dropped out the clutch"? Literally, as in physically drop out?

The clutch cycling switch, (mounted to the accumulator) cycles the clutch when the system is operating. If static pressure on the low side drops below ~42psi, (empty or low on refrigerant charge) the compressor clutch will not engage.

There is a nut in the center of the clutch plate, it is threaded onto the compressor shaft. You should be able to rotate it fairly easily, clockwise, using a socket and ratchet. If so, the compressor is not locked up.

I'm sure the bearing was destroyed with that much heat. If the belt pulley wobbles at all, then the bearing is definitely shot.

My compressor was bad and it would turn a little then bind up some but could be turned past the bind and spin a little more them bind up again.

I put a used, but known to be good clutch on mine and when it engaged, the compressor was making some pretty horrible noises. Kind of sounded like when some shuffles a deck of cards, but about 10 times louder.

I seem to remember the new compressor not binding or dragging at all, but I didn't play around with it too much. At that point I was just ready to have the A/C back together.

Howdy!

The clutch on my Blazer is pressed on as was the pulley and bearing. Got the bearing off and it is not smooth and very hard to turn. Also, the compressor is difficult to turn. I attached an installation tool to the shaft and used a socket and ratchet to turn it. It also was not smooth and was difficult to turn with an audible grinding sound.

My best guess is that the compressor seized which caused the pulley to rub the clutch, that created the friction fire which fried the pulley bearing. Regardless of what happened, I'm going to try and find an a/c delete (or non-a/c) pulley and shorter belt to put in so I don't have to pull the compressor until I'm ready to repair the system. Most people think I'm talking about the bypass pulley, but that's not what I want because it requires me to evacuate the refrigerant and pull the compressor. My next option is to find a good pulley and bearing and put that on, disconnect the wires to the compressor and coil, and drive it until repairing the system. Last option would be the bypass pulley, but I don't want to do that unless it's my only option.

A couple of years ago my Bravada's AC compressor locked up and wouldn't even let the engine turn. I was able to locate the AC Delete Bracket and Pulley at Advance Autoparts but they had to order it for me. I don't recall how much it cost though....

Thanks for the heads up. I called O'Reily's, AutoZone, Advanced, and Full Service asking about an A/C delete pulley or non A/C idler pulley and no one I talked to could find the part, like it didn't exist. It was frustrating because A/C was on option so they were obviously made for vehicles w/out it. I gave up and just went to a picknpull and found a good pulley. Installed it and driving without A/C until the spring when I need and can afford the repairs.

That's the problem with the auto parts stores, if you don't give them the part number, you'll probably get the wrong part, or none at all;) They all carry Dorman products, or can order it. Cost is around $40. This part is used on a TON of GM vehicles.

Dorman Products - 34175

Howdy!

I know it's about a year late, but...Thanks for the response Captain, but that was not the part I wanted (as discussed in detail in post #6 and 8). As I understand it, the bypass pulley is installed where the compressor is normally located. The ac delete (or non-ac) pulley is installed in a different location and why it requires a different belt. Just want to clarify so any others looking for either pulley (bypass or ac-delete/non-ac) understand the difference.