hi again thiswas my first topic but now i have some more info on it

i thought it only done it while the aircon was on...well now i turned on the heated front and rear windows and it does the extact noise......cud it still be the crank shaft bottom pulley...or could it be the alternator making cthe wierd knocking/tapping sound...as it working twice as hard..........my first question is below

hi all wonder if any1 can help.....i have a mondeo 2.0 tdci dura-torq 54 plate...and now all of a sudden it has this wierd tapping/knocking sound comming from the engine drivers side....it sounded like it was comming from the main tens puller so i changed it today but its still there but not as bad but can still hear it....it only does it when the air con is on i have been told that it could also be the bottom crankshaft pully....could it be this ????? any help would be great