Trying to find the article where a heater core was used in the fresh air blower, for the defrost/heat.
Now that I think about it, the under dash unit from Renegade had tubing running from it that forked, and had a valve, for lack of a better word that you could flip, and divert air to the defrost, but for some reason never worked. Maybe once I get it all unhooked, can look and see what is all going on, and would be one less thing to dream up.