Well, I figured out the problem with the heat. Don't know what I was thinking about the thermostat. The lines don't even run out of it. The problem was the way I was trying to operate the controls. I left the slider on dash vent for air flow. Vintage Air sets their system up where you can't get heat unless the lower heat duct is selected. I was setting the mix for dash and floor which allowed some heat to come at first, but once the air had been flowing a little while, the cool air would take over the little hot coming through. Once I slid the control to full floor, the heat came on great. I guess I've become too used to modern AC settings that let you put hot air through all vents. At least I can Chalk it up to dumba$$ and not something malfunctioning. BTW, the heat is very good along with the cool in these units. I highly recomend them. FYI--I decided to use non AC front springs during the rebuild of my front end and they worked great. The Vintage Air compressor probably doesn't weigh much more than the alternator so you don't need extra spring on one side.