A thermostat controls the AC temperature in your home. A thermostat is preset in the factory to display the temperature in either degrees Fahrenheit or degrees Celsius. While thermostats in the United States are usually preset to Fahrenheit, Canadian models are preset to Celsius (this is because Canada now uses the metric system). Therefore, if you are in the U.S., but your thermostat originated in Canada, you may find the thermostat doesn't quite fit your needs. While programmable, digital thermostats can be changed from Celsius to Fahrenheit using a series of menus, and you can change manual models by accessing the thermostat's interior.
Remove the cover from the thermostat. The cover should pop off easily, with a slight tug.
Locate two small, black switches inside the thermostat.
Find the switch labeled "F and C."
Move the switch to "F."
Put the cover back on your thermostat.