I gave up trying to find the "AC pre-wiring" after I had disassembled most of the interior. I di discover the the Blue wire and White wire in the AC opening was
12V DC so it was not necessary to run additional
12V power into the space.
I pulled new Control wires and two Furnace wires from the Aft Bulkhead location in front Bedroom ( where the previous analog T - Stat was located) up and across the Shower, thru the locker and then into the ceiling space above the refrigerator and locker. All the wires are hidden doing it this way.
I wired up the CT Thermostat, installed the new control board and everything works great.
Thanks, D