AC compressor vibrating

Hi all, I have a car with a transplanted Chevy 250 in-line 6. Recently the AC compressor has seemed to exhibit more resistance and much more vibrating than usual. I have checked the belt (fine) and tightened the seucring nuts and bolts. It still sends out a vibration that can be felt throughtout the vehicle. I am thinking the clutch is bad? Any ideas? Thanks!

Install a set of AC pressure gauges. Maybe the high side is to high for some reason. Is it still blowing cold (check with gague). Any odd noises? maybe the compressor is getting ready to lock-up. Or a AC clutch problem. Any change in engine performance? Loose a blade on your fan?

Also check the mounting brackets and any brass or steel bushings. Brackets for these older engines have a habit of developing little cracks in them, especially wherever a bolt/nut is attached. It doesn’t take very much grime to disguise where cracks are hidden. Otherwise, it’s most likely an imbalance or wear in the compressor. Bearings, clutch, over/under charge, etc. Have you upgraded to R-134A yet? If you have access to remnants of the R-12 stock, keep it quiet. You could start a riot. Remember that converting to 134A involves a heck of a lot more than just dumping in new 134A. The whole system needs to be flushed of the refrig. oil used for R-12, changes in certain control devices such as the TX valve, etc., and on and on. Be ready for price shock if you’re not already converted to 134A. Even if you can find an A.C. shop to rebuild your R12 compressor, and if that shop still has some R12, the price PER OUNCE of R12 is astronomical! I’m just hoping that your system is an R134A system.

Thanks for the reply oldschool, Yes, I still get cold air, it is a bit noisey. All the fan blades are still there. The engine is running good, no change. Thanks again.