New to the board and I have to say this is the most useful tool I have found in working on my 300CD turbo diesel.Thanks for all the help!

Alright, the problem is that at idle or higher speeds at rest or on the road I get this hissing, metal scrapping, noise out of the compressor. I know it's the compressor because it's quiet as can be with the air on. The air blows nice and cool when I use it except when the clutch disengages. Any help would be much appreciated....

Thanks