Sound coming from around serp belt

Hi I have a 1996 Saturn sl2. This sounds crazy I guess but it seems to be making a noise best described as a clanking around the crank pully and tensioner. It sounds like two pieces of metal slapping together sort of. It is worse when the ac is on. however it disappears when in park or or neutral. I replaced the tensioner, and lower motor mount. But the sound remains. it doesnt sound like its coming from inside the engine. I am thinking of replacing the crank pully next and maybe the belt although neither seem to be in bad shape. Any suggestions? I am getting pretty annoyed with the noise.

hard to say - my thoughts -

first, TSB 00-T-39 covers a rattle nosie in the same area, its caused by the heater pipe/hose hitting the dash area/firewall(they call it dash, i call it firewall), and that becomes louder when in drive or reverse. see if using a long screw driver to pry the pipe away from the dash/firewall makes the noise goes away. if this is the problem, tell me and i will post the full TSB.

if its not... i would start by double checking the other three mounts. then jack the front end, remove the wheel, start the engine and see if you can get a better idea or where it coming from. be careful, this isn't the safeist idea.