This feature was introduced as of version 4.3.0. When selected, it controls both the furnace and the A/C unit at the same time. The HEAT and A/C set points are set individually by using the regular HEAT and A/C modes. The set points must be at least 5 degrees apart in order to select the HEAT – A/C mode. Once selected, the furnace kicks on if the temperature drops below the HEAT set point, and the A/C unit kicks on if the temperature goes above the A/C set point. The A/C unit operates exactly the same as if it was in A/C AUTO mode, the blower changes speed automatically and turns off about 30 seconds after the compressor kicks off.
You can change both set points at the same time by using the UP and DOWN buttons.