where's the heat?

[jos1 at cornell.edu]

A question for those of you who BTDT:

How do you get enough heat in an Audi?

My '89 100Q is now on its third thermostat, the swaps having been done
because of the suspicion that the (previous) thermostats were not
closing -- the operating temperature, according to the temp gauge,
stayed at the 2nd or 3rd notch of the gauge in the kind of temps we're
experiencing here currently -- about 10-15 degrees F. Of course the
heater produced only a a whisper of tepid air, just as it does now. In
the past, mo Ovlov produced HEAT within the first 5 minutes of driving.
Obviously, swapping thermostats has made not one bit of difference.

What's going on?  Is there an Audi secret I shold be privvy to?

TIA for all tips, and happy holidays.

jos