Parked my A6 2.8 1998 and heard fan noise - thought cooling fan was still on. Left overnigh. next day battery dead and drained. Put charger on and heard fan noise from engine compartment in area of the air filter. Thus batery won't charge - all power from the charger is running this fan--- same thing when I tried a jump start. What is the fan? How do I get it off? DH3