On the Rear A/C unit.
I am no where near that point on my 55 Burb but I agree a dash only unit isn't going to keep thing cooled down. I am in central Texas and even with windows down and vents open we keep clean rags handy to wipe off the sweat.
Recently after a death in the family I noticed that the "Family Car" had A/C blowing from beneath the back seats. While questioning the driver (A fellow Car Guy) I learned that the system provides both Heat and Air from the same unit using a reversing valve just like a heat pump for an all electric home. The driver did not know where the unit came from but he did know that the car came from a Coach Company in Mena or Fort Smith Arkansas.
This would only require freon lines run to beneath the back seat and would be much simpler that any type of duct work. I haven't worked on this yet, because I am nowhere near that point, but if someone can track down the coach company and find out where to source such a unit it would anwser a big question for a lot of us southern boys and provide heat for the northerners as well. Face it, with Global Warming we all need to add A/C.
Burb'r
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CHARACTER, The Only Building Project You Never Finish.--------------------------------
1955 2nd Series Chevy Suburban(2) Modern Vehicles that get me around