I own a 2000 Audi A4 Quattro 1.8T and lately it has been making this weird noise after I turn the car off.The sound it makes is like that of a fan spinning or winding and almost as if something is charging it self up.This happens continuously while the car is off and eventually ends up draining the battery's life out. The problem noise is happening around the air filter compartment Area,I'm thinking it might be the turbo.Can anyone help me trouble shoot this problem? Thanks.