Since air conditioners use more energy when they cycle all day, it is cheaper to let your system operate at full capacity when you're home instead of running it at a lower capacity all day. The more energy you use, the more money you'll pay in monthly utility bills.

How Long Should It Take for the AC to Cool My House? Generally speaking, it should take one hour per degree to reach the temperature set on your thermostat. For an average three-bedroom home, it typically takes about three hours.

Maintain and Stay Cool On average, 15 minutes is how long should an AC run. If your AC is running longer on mildly warm days, then you may have a problem.

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.