Upgrading - Dometic Single control to a one with a timer

Due to the wiring of your single zone tstat, you CANNOT add any other tstat. Yes, you will have to purchase the 12 button Dometic wall tstat AND the control board that mounts in the AC unit to go programmable. The Single zone only uses 3 wires, and the 12 button uses a phone type cable with the phone modular ends, but I believe Dometic makes a jumper wire kit to use on those wires. If NOT, then you will have to run a 4 wire phone type communication cable from the AC to the wall tstat hole. Doug