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My newest issue I discovered in this car is when I went to take it out on a beautiful labor day, I noticed when I turned the AC on I got a really bad vibration. Turn off the AC and the vibration stops.
I checked my AC compressor and have a feeling the AC clutch assembly is shot. Not sure if it's a bad bearing or what, but I can push spacer (I think that's what it is) around between the pulley and the compressor body. I still get cold air when the AC is turned on, so I don't think the compressor itself is bad.
before starting AC (moved spacer back to center) spacer moves freely
I've done a bit of looking and it looks like getting the clutch assembly isn't possible without removing the compressor. This means evacuating the AC system, and it's R12...I really didn't want to go through a 134a conversion right now, as I think that means updating the whole system to handle 134a.
My plan for the time being is to remove the belt to the compressor and run the rest of the season without AC as the weather cools down. I figure this will be a winter project.
So my questions to the community are:
Is there any issue with removing the AC belt for the time being? I'd like to do some driving and the weather's cool enough where I don't need the AC.
Is it possible to change the clutch assembly without removing the compressor? I know there are some unique tools I need, just not sure it's enough space.
If I have to evacuate the system, is there anywhere in SE Michigan that will evacuate and recharge with R12? Unless I'm wrong the R134A conversion is more than just the compressor.
What am I looking at in terms of parts and labor to convert to R134a? I don't mind wrenching, but I know I'll need the evac and refill done by a service.
No expert on A/C compressors but looks like the clutch is shot and way out of balance.
I am surprised it didn't damage something when you engaged the clutch.
By all means, just remove the belt for now.
That style comp is longer & heavier than another model. I see you are not into original parts anyway, so you may be better off finding the smaller compressor from a used Corvette parts supplier.
Rumor is, they can be pricey however.
When my A/C quit, I removed my comp, put it in a box for the next owner.
No expert on A/C compressors but looks like the clutch is shot and way out of balance.
I am surprised it didn't damage something when you engaged the clutch.
By all means, just remove the belt for now.
That style comp is longer & heavier than another model. I see you are not into original parts anyway, so you may be better off finding the smaller compressor from a used Corvette parts supplier.
Rumor is, they can be pricey however.
When my A/C quit, I removed my comp, put it in a box for the next owner.
Same here, surprisingly everything still seems ok.
Thanks for the tip on the belt! I figured it would be ok, I just wasn't sure if removing the belt would throw the engine out of balance.
I was thinking when the time comes, I'd do an R134a conversion, though that's gonna cost some money and require more than just the compressor replacement. I'd rather wait and do when I really need to.
Did you have an issues evacuating the refrigerant? Was it using R12?
The clutch on ur compressor is shot. U can have clutches replaced. R-1:2 is still available. Look on E-bay. There may also be someone local to u that has R-12 to sell.
I would stick with the R-12 if I were u. IThat is what ur system was designed for and it is the coldest. Plus, ur system is working fine ( minus the clutch issue).
Having the clutch replaced along with the bearing it rides on and the compressor front seal is less expensive that converting to 134A.
Last edited by Bob3700; Sep 5, 2025 at 09:59 AM.
Reason: Adding info
The clutch on ur compressor is shot. U can have clutches replaced. R-1:2 is still available. Look on E-bay. There may also be someone local to u that has R-12 to sell.
I would stick with the R-12 if I were u. IThat is what ur system was designed for and it is the coldest. Plus, ur system is working fine ( minus the clutch issue).
Having the clutch replaced along with the bearing it rides on and the compressor front seal is less expensive that converting to 134A.
Agreed, I'd much rather do that than go the R134a route, it's just the hang ups I'm running into, like where can I get R12 evacuated and reclaimed if I have to take the compressor off? Hardly anyone will deal with it anymore. Also, ebay seems to be full of envirosafe R12, which I think isn't technically real R12, it's similar but flammable...? I don't know, from my reading it sounds different.
I may just get the unique tools and see if I can do the clutch replacement with it still in the car. I can report back on how well it goes. Just gotta be mindful of those snap rings...sounds like they're a pain to get to and easy to lose if you can get them off.
74 AC Compressor Clutch Vibration
