The short answer is yes, it is cheaper to leave your air conditioner on all day. But this does not mean that you should leave it on full blast, keeping your home so cold that you need a sweater or jacket to be comfortable.

How long Is An AC System Refrigeration Cycle? In general, an air conditioner runs for about 20 to 25 minutes until it reaches the desired temperature, then turns off and recycles throughout the day and night. An air conditioner should run for 10 to 15 hours a day on typical summer days.

Increase the temperature You can save 10% a year on your cooling bills by setting your thermostat just 10 to 15 degrees Fahrenheit higher for 8 hours each day, according to the Nebraska Energy Office. The US Department of Energy recommends aiming for an indoor temperature of 78 degrees Fahrenheit when you're at home.

Here are a few programming timing tips to help you create the best set-it-and-forget-it heating and cooling schedule for your home: Shut down heat or air conditioning 20 to 30 minutes before you leave home each day. Turn on heat or air conditioning 20 to 30 minutes before you come home each day.