[Richard]

I ran into a slight glitch in my approach. Because the relay board is between the Tstat and the control board on the AC unit, turning off the tstat, does not immediately turn off the AC unit. As built the AC unit would continue to run for five minutes.

I didn’t want to wait 5 minutes to shut down the generator, and I wasn’t going to shut it down with a load on it.

The solution is very simple and straight forward. There is a terminal on the board labeled END. If you short that terminal to 12V Positive, the board opens all the relays. I added a surface mounted toggle switch at the tstat to be able to shut the AC unit down quickly.