You had the 4 button Dometic wall CCC Tstat system which was discontinued in 2002. The replacement for your specific system is the 5 button. To replace, you need the 5 button wall tstat and BOTH upper AC unit control boards. They are BOTH plug and play. The only wiring that you need to strip and connect is at the front AC unit where you will have a Positive and Negative and the 2 blue furnace wires. The 5 button will also include a NEW freeze thermistor that must be installed in the evaporator fins. You DO have to remove all the wires on the existing control boards and install on the new control boards. IF you model has AC only and NOT a Heat Pump, you can upgrade to the current 12 button Dometic wall CCC system, which is programmable. This would require the 12 button tstat and the 2- 12 button AC control boards. Doug
