Erratic HVAC
 

2008 A6 Avant Quattro 3.2, 132Kmiles. New to me.

The HVAC system seems erratic. When I first get in the car it warms up, then ceases and my legs/feet start getting chilly. Also, the fan doesn't seem to be particularly strong. This issue with fan speed also infected my 2009 VW Jetta TDi Sportwagen. In comparison, my old Accord V6 HVAC was robust, you could really feel and hear the fan when you turned it up full.

I can barely feel anything out of the dash vents either.

What gives here?