This only happens when the a/c is on, but i get a tapping sound from the valve cover at idle (possibly timing chain tensioner?) and with initial throttle input i get a short low pitched squeal sound, again only off idle/low rpm

Some background:

05 R53
Just replaced damper with +2% ATI, new belt, tensioner good.
16% pulley
a/c just serviced at dealership
tapping sound isolated to area over #1 cylinder with the old "ear to long screwdriver" trick
the secondary fan kicks in hard and loud as soon as the A/C is on and there's a ton of heat generated in the engine bay within minutes

Any help/ideas much appreciated i'm unsure where to start..