Air conditioner thermostats & digital thermostat are equipped with two fan settings, 'on' and 'auto'. When the thermostat setting is set to 'on' the fan runs constantly and when it is set to 'auto' the fan runs only during cooling cycles when the air conditioner compressor is in use. When the air conditioner is in use all day, the cooling compressor only operates about 50 percent of the time, that is, for about 12 hours. The extra fan operating time that occurs when the thermostat is set to 'on' can add roughly $25 to monthly air conditioning bills. Using the 'auto' setting, alternatively, saves energy and money because the fan operates fewer hours. Besides achieving energy and cost savings, the 'auto' setting also promotes more comfort by offering better humidity control as moisture removed during the cooling cycle is re-circulated back into the home while the compressor is off.