AC unit or pulley makes grinding noise when off.

The air conditioning pulley seems to be making a metal on metal grinding noise and chatter. When you turn the AC on it stops. Is this a common problem? Bad bearing that only makes noise when not under load? Does the whole unit need to be replaced or just a pulley assembly? Please help.

Are you sure that its not just the serpentine belt? Could the belt be slipping?

Jeremy

The belt is fine. Either the pulley/bearing/or something in the ac unit isn't right.

The grinding noise that you're hearing is not a bad bearing. It's your AC clutch that isn't fully disengaging.