In three hours, a properly running central air conditioner should be able to chill a moderate four-bedroom home by ten degrees Fahrenheit The temperature scale on which water freezes at 32 degrees and boils at 212 degrees, designated by the letter F. <br />To convert Fahrenheit to Celsius, subtract 32 from the Fahrenheit number, multiply by 5 and divide by 9 (77–32 equals 45, times 5 equals 225, divided by 9 equals 25 degrees Celsius). " data-gt-translate-attributes="[{"attribute":"data-cmtooltip", "format":"html"}]">Fahrenheit. Although the cooling power of your air conditioner is dependent on its size, age, and wattage, your home should feel noticeably cooler after a few hours.