The "conversion" is, replacing your AC control boards AND installing the 5 button wall CCC tstat. You MUST replace each AC control board with a 5 button control board. The main difference between the 4 button and the 5 button is 2 things.
1. the 5th button changes zones
2. The 5 button has a better Freeze Thermister that works for both AC's and Heat Pump models. You must replace your existing freeze control with the new Freeze Thermister and it does come with the control board kit. Doug
NO, they are not difficult to install. Plug and play.