Duo Therm Heat Pump weirded out

Hello Doug, I did replace the AC unit about a year and a half ago (it's the new style Duo Therm), but they sold me a control unit (the electronic box that fits up in the new AC) that was supposedly designed to make the new AC work with the old five button CCC thermostat. I think I was concerned that there was no way I could run a new thermostat wire up to the unit, as it runs through the wall, and somehow I understood a new thermostat needed a different wire. I really don't remember why I stayed with the old thermo. It has worked great for a year and a half until this morning. My control unit is a 3109226.005. So I'll try the thermostat reset. Otherwise, you think its the control unit., is that right? I wasn't sure whether it would be the thermostat or the control unit. Thank you very much for the info. Duo Therm is impossible to get tech support from.