Old compressor leaking around the case, replaced with new Factory Air compressor, dryer/rec., expansion valve, PAG 150 and a couple cans of R134. Now working fine, pressures normal and air temp a little over 40 deg., but I get a grinding sound when the engine is above 1800 rpm. Hear it on the road or sitting still, feel it a bit in the gearshift even. Did the refit right, bolts are tight, brackets in place, pulled vacuum and all. Anyone ever run into this? Hate to take it back down and the hassle of getting the compressor replaced, and it might be something else even. Any suggestions? This is an 88, V8, R4 compressor.

 

could be a slipping compressor clutch-just opserve the
clutch while revving the engine above 1800 rpm,could
have scored clutch surfaces or other problem.

 

Serp system? Might be the idler pulley - the new compressor avtually working wold put a greater load on the system. Place long screwdriver blade on the idler pulley housing, and place plastic handle against ear - then rev the engine at various rpms. Try the A/C unit as well. The vibrations will run through the screwdriver and vibrate the ear drum - easy to pinpoint noises this way as they are accentuated (poor man's stethescope). Just BE CAREFUL - watch those belts and moving parts!

 

Thanks for the tips, I'll get back into it tomorrow. Seems like it would not actually be in the compressor as it only gets noisy at a certain rpm, quiet below 1800. Just like a tire that only vibrates at 60 mph, right where I drive 90% of the time.

 

Compressor seems to have fixed itself. I suspect it was paint on the pulley grooves, or maybe some oil on it. Working fine, right now anyway. Knock on wood.