I have a 1996 A6 Quattro with the 2.8 engine. I get plenty of forceful, hot air out of the central vents, but nothing out of the footwell or defrost vents. Difficult this time of year in New England. Manual controls (up/down arrows) have no effect. Suspect a flap motor somewhere is stuck or inoperative. Where are those motors located and has anyone seen a procedure for replacing them?