Clutch noise

Just purchased a used 1999 323i, 5 speed manual, nearly 160K on the odo. I find there is a rattling noise - sounds like marbles - coming from under the car, about center under the front seats, when sitting at idle with the a/c going. Shut off the air, noise goes away. Strange part is that when I hear the noise and press in the clutch, the noise goes away also!

No idea how the clutch relates to the a/c, if at all. Can anyone offer suggestions on what to look for / problem might be? A/c works fine otherwise, as does the clutch.

Thanks!

If it wasn,t for the a/c dilemma I.d say you may have a worn thrust bearing.