I have seen your pictures of the front and side panels and wanted to know how the framing and 1/4 or 1/8 inch inserts were joined? Looks like you inserted the thin panel into the 1 by 2. Any sketch of what you did?
The 2" space is what caused the problem, if the failure was due to heat. You increased the R value 10 fold from 0.09 to 1.0 or so. If glued directly, no issue!
I see all that now, thanks! On this setup you were going to run a frig and fan. Run the frig on the cool cycle and the fan on the heat? Or run both on the cool? Or wire one outlet constant on and run the fan constant on?
Here is a question from a total novice. Why do you go through all the wiring joining and use the ground as neutral? Can't you just run power to the unit, one set of in wire, and then one set of wires from cooling to the plug as well as the heating to plug? I note there is not ground wire used.