Hi all,

Once again, I have a question concerning a non-Volvo, but since you are all so technically savvy, I like posting car questions here. And it turns out, my friends like to come to me to ask questions because I'm an engineer and like to work on my own cars.

So, my friend has an older (maybe early to mid 90's) Chevy Lumina (it's blue so we call it the Blumina). He just had an issue with the alternator and in the course of replacing it noticed the belt had "fallen off" as well. So he bought a new belt and turned the car on. Well, in the end it appears that the A/C compressor pulley is locked up and locking the belt up. He said the "big pulley" (I'll call it the crankshaft. :-) was spinning really fast and causing the belt to smoke since the belt wouldn't move. The auto parts guy came up with a quick solution - he bought a smaller belt and skipped the compressor.

Anyway, I've read tech's posts about re-shimming the compressor and was wondering if that's the sort of thing that could cause one to lock up. Any other ideas? My friend's low on cash, so I'd like to help him fix the existing compressor rather than buy a new one.

Thanks!
CJG

 

Hello 99V70,

As to the compressor, the first thing I would do is to tap the compressor with long extension or soft-face hammer to see if it frees up.

The next thing I would do is to remove the compressor, ensuring that the system is empty of refrigerant. If there's still some pressure, I would havethe refrigerantrecovered at a shop to be legal, or at a hidden place, quietly (face & hand protections, zzz...)..... When the compressor is removed, cap off the ends of the hoses/tubes and compressor ports with something to prevent moisture from entering.

After removal,I would try tapping the pulley portion of it with a soft-face/plastic hammer (or a regular steel hammer & a piece of hardwood) from every possible angle (mostly to the rotating direction; the impact may free up binding) to see if it frees it up, and try turning the pulley by hand/socket tool w/a breaker bar. If this doesn't do the trick, your friend may have to give up some $ and buy a rebuilt compressor. I wouldn't get one from a junkyard, as you never know the condition. Upon installation, it may also need a new receiver/dryer unit.

I would also check to see if it uses R12 or R134a, asthey are not compatible. Since the production of R12 has been outlawed in many parts of the world and the resource is getting scarce, see if there is a conversion kit for the A/C. The major difference seems to be the type of O-rings used, as far as I know.

I did a bit of research on the compressor and 1990-1993 seem to share the same unit, where as 1994 & 1995 models share different ones. The OEM seems to be Delphi. Price range is just about average; $230 or so. The resource for this compressor seems very scarce, and many places didn't have it in stock. This is the only site that seems to have them, but not sure if they have them in stock, though:
http://www.discountacparts.com/chevr...compressor.htm

If you want to be sure, you need to know the model year, trim, engine size, etc... After browsing through Delphi's HP, all compressors used on Lumina seem to have centre nut, so I'm wondering if you can somehow try to turn the compressor with a socket tool with a breaker bar (Warning: if the internal parts are rusted together,a breaker bar may actually "break" something):
http://go.delphi.com/cs/welcome.aspx

If your friend doesn't care about not having A/C, here's the last resort:
http://www.1aauto.com/1A/ACBypassPulley/Chevrolet

It's just a "dummy" bypass pulley.

However, if your friend insists on having the A/C repaired without buying a rebuilt compressor, here's what I would do though I DO NOT recommend it.

1. Buy a generic A/C service manual (Haynes?) or just read the compressor section at a shop without buying it[8D].
2. Carefully take the compressor apart, taking pics at every step.
3. Determine the cause of the binding and recondition/replace the part (get a compressor from junkyard and hope that the particular part is serviceable).
4. Put it back together and reinstall on the car.
5. Have the system evacuated & recharged at a shop with the correct type of refrigerant.
6. In case if you see/hear something unusual, RUN[8D]!!!

Sorry I'm not much of help in this situation. I believe Tech could give you better ideas.


JPN

 

Try turning the inside and outside of the pulley if one is locked up then most likely the pulley/clutch is bad.

The only thing to do besides replacing the compressor is to find another compressor that is bad and has a good pulley/clutch setup and swap it over.

 

Hi guys,

Thanks for the tips - they are much appreciated.

First of all, I should note that my friend bought that (or a similar) bypass belt that he's using for now so that he can get around town (in the steaming hot Alabama heat) without a/c.

Next, I'd thought I'd read somewhere about tapping the pulley with a hammer and I'd mentioned that to my friend (and another friend/advisor who's gotten involved) but there was some debate between us about the best way to go about it. One option is to tap it with the power to the a/c on, but no belt. The other is the same but with the fullsize belt on (which means crankshaft pulley will be smoking the belt) - working quickly. The third option is the one where we take it out and tap it. At this point he's without a/c anyway, so if the first two don't work, we might as well take it out and see what we can find out. (By the way, when I was replacing my own car's compressor I found a shop that would legally recover the refrigerant for only $20, so that's no problem.)

I do need to get the exact model so that I can check the refrigerant type - I've seen plenty of info of conversion kits, so that should be fairly straight-forward. By the way, I'd also check www.discountacparts.com - that's where I got my compressor for the Volvo earlier and I noticed they had an option to buy just the clutch/pulley for less than the full compressor. I think for those prices though, he might opt for no a/c (which means if we go anywhere together, I'll be driving - I need my a/c).

I'm thinking the final option you, JPN, mentioned could be fun for me. I actually worked for a refrigeration/HVAC engineering firm where we mostly did designs for grocery stores (mostly computer based, not much hardware). While there, I did get a chance to go to a compressor tear-down class that was interesting, it'd be fun to do that again. I like looking for problems and I'm pretty familiar with how a compressor is supposed to work, but I might miss some minor details that could be causing the problem.

Anyway - thanks for all of your tips. If we do get a chance to do it, it'll be a few weeks away since I'm heading out for a bit. But, I will be sure to take pictures so I can post them here for your enjoyment.