As per the title, my AC pump is rattling when running in ECO mode on the Climate Control which I do most of the time. When you select the mpump on it vanishes.

I know the pump is controlled via a clutch mechanism which allows the pully to turn but not the pump when it's selected off. I would understand if the rattle was there when it was running, but for it to be there when the pump is NOT running is a bit odd...

Would this point to the pulley bearing...? Being the 3.0 it's not a huge issue as all it drives is the alternator and the AC pump if I remember rightly...