I have a 1996 c4 corvette with 58000 miles. My problem is that the heat and ac will only come out on the floor and the defost(windshield).It does not matter what switch you depress.Is this a door motor problem in the
blower motor area or should I be looking somewhere else.Thanks in advance for any help.

 

Look under the pass/side fuel rail cover for a vacuum valve. Could be the problem?

 

Did your problem get solved or not? I am having same issues.