It's in pain - take the nipple clamps off.
Audi: 2008 A3 VR6 DSG, 2008 TT VR6 Manual
"Anyone who looks at the Audi A3 3.2 DSG and sees an overpriced economy car should not be allowed to play with Rottweiler puppies."
- Robert Farago, The Truth About Cars
It's supposed to freespin but the clutch often locks up so it becomes a plain pulley. You have to compress the tensioner, use a pin to hold it in place, lift the belt off of the pulley, use a non-metallic rod (like a pencil) to push into the vent holes to hold the alternator's internal fan in place, and then see if you can turn the pulley in one direction. If it won't turn either way, it's time to replace the pulley/clutch assembly.
I just found out the hard way that it can cause vibrations in the belt, which shakes the A/C compressor, alternator, and tensioner. This can cause squealing and rattling near idle. Especially when accelarating and when there's a load from the compressor. Eventually it damages the A/C pulley clutch and/or shaft.