Hi Duck Pond.
Usually, you set the mode to either Heat or Cool, then adjust the set point temperature. But I'm guessing there's a question behind your question - perhaps something doesn't work the way you expect.
As it's the time of year that most people turn on the furnace for heat, a common question is why the thermostat doesn't activate the furnace. You probably have at least 2 thermostats in the coach. Only one is connected to the furnace.
Another common question is about the air conditioner blower starting with the furnace. If that's the case, change the mode to FAN, and set the fan to AUTO rather than HIGH or LOW.
If it's something else you're trying to figure out, let us know which thermostat you have and exactly what information you're seeking.