drive belt makes alot of noise

I have a 95 buick lesabre custom,345,817km's,3.8L 3800.Alot of clicking noise coming from either the tension pulley,power steering or air conditioning.It gets alittle quieter when i turn on the AC.I would like to know which one so i can change it.I dont want to judge for myself and end up buying 3 different parts.It's not a sqealing noise.Clicking.Not lifters either.Its coming from one of the pulleys in belt area.Could it be the air conditioning.The clicking starts when the clutch on AC pulley stops.If i don't have the AC running it will be louder and more consistent.When AC is on,it only makes noise periodically.I think the rear motor mount is gone.I havent been under yet,but when i give gas and release it clunks.When i throttle when hood is up,you can see the engine tilt back,then clunk,then forward.Sides are good.I woulfd like to fix myself if its an easy job,like pulley tensioner,altenator.I put a screw driver on the altenator, tensioner,and power steering.I can feel it in all 3.