I have a '96 JGC and the heat does not work. I have flushed out the cooling system and the heater core and nothing leaks. When i drive for a while and turn the heat on, it just pumps out cool air. Does anyone know what it could be?

You did use coolant (antifreeze), right? Some people put straight water in as a cheap substitute for coolant, which sometimes is fine for summer but for winter it willl not cool distribute the heat to the heater core like coolant.

I had to flush/reverse my heater core last winter due to a no heat situation (you might want to look it up on the forum, I posted a thread with some handy info on how to do it).

Other then that the problem would lie in the control assembly.

Yea i used antifreeze, but i will look at your forum. thanks