[s-cars] Heater gone into Hades mode

[MLBess at aol.com]

A new issue (besides the cracked steering rack on my '95 S6 which has been
given the body shop treatment and will be reported on later) has cropped up
on my wife's '95 A6Q.  From the looks of things the HVAC system is the same
on the A6 and the S6 so here's the question.  The heater now has a mind of
its own.  At any temperature setting higher then LO, the heater pumps out
heat relentlessly without any modulation, no matter what the interior or
outside temperature.

Anyone BTDT?  Is it a stuck heater valve or has the HVAC computer died? Or?

TIA,

Mike Bess