I wanted to post this in the hope it will help others who have ATC problems.

I finally took my 2000 limited to another dealer
(Mercury) and convinced them that I did have a problem, something my selling
dealer refused to acknowledge.

picked it up today and works great, although I haven't yet tested it
thoroughly.  but I can already tell the difference.  previously, if set
below 80 degrees, it would blow cool/cold air.  it now seems to work as it
should, blowing warm air (even at 70-72 degrees) and increasing/decreasing
fan when needed.  my feet no longer get cold.  outside temp today is about
35.

the only problem found; the 'car temp sensor assy', about $41 for the part.
labor, of course, was additional.  in addition, the service dealer said
there was some lint blocking the sensor, so you might check this.  I do not
know where the sensor is located in the car.  since I have had this problem
for several years, I feel sure the sensor was originally bad.  it was NOT
the blend
door.

needless to say, the place I purchased     my car will not have a repeat
customer.  I live in dallas-ft worth area.