A thermostat is an apparatus for maintaining the temperature of a system within a particular range by directly or indirectly controlling the flow of heat energy into or out of the system. All air conditioners have thermostats that can be manually operated or automatically preprogrammed to work at regulating the room temperature. There are many ways in which you can use an air conditioner thermostat effectively.
One of the most successful yet economical ways to reduce your air conditioning costs is to adjust the thermostat setting on the air conditioner. The savings are more noteworthy when you set your thermostat at 78 degrees Fahrenheit or higher. For each degree you raise the thermostat setting, you reduce seasonal cooling costs by 7 percent to 10 percent. In doing so, you can use ceiling fans in addition to the air conditioner and thus, save a lot of money.
Most centrally located air conditioner thermostats 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.
Thus, thermostats play an important role in the cost and function of an AC.