On a 90-degree day, your AC system might need to run more frequently to maintain a comfortable indoor temperature. Typically, an AC unit should run for about 15-20 minutes per cycle.
When temperatures exceed 100 degrees Fahrenheit outside, setting your air conditioning (AC) to around 75-78 degrees Fahrenheit is generally considered efficient. Here are some reasons for this recommendation:
The average air conditioner run time for a typical summer day is 12 to 16 hours. But if it's especially hot or humid outside, it could run for 20 hours or more. While your air conditioner will run for several hours during the day, it doesn't do so consecutively.
Cooling a house from 80 to 72 degrees is a common goal for many, especially during the peak of summer. On average, this process takes roughly two and a half to three and a half hours.
Air conditioners shouldn't generally work all the time unless the thermostat is set to ``fan on'' (inadvisable). A correctly sized and well-maintained AC system should run for 15 to 20 minutes, two or three times every hour--with longer cycles in the higher temperatures of summer.
On a hot day, your AC might run for several hours, especially during peak heat times. For example, during the hottest part of the day, your AC could run for 8-12 hours total, depending on factors like your cooling load, insulation, and if your house is exposed to direct sunlight.
You're likely wasting energy, putting stress on your system, and heading toward steep repair bills. Don't let cooling your home become unnecessarily expensive this summer. Use these six simple questions to find out if your AC is running too long (and what you can do about it).
Typically, it takes about an hour for an average-sized air conditioning unit in typical conditions to lower room temperature by one degree Fahrenheit. But remember, 'average' doesn't mean 'always'. Like people, every AC has its personality – some are sprinters while others prefer marathons.
In general, 80 degrees is too hot for a house if people are inside. However, if people aren't home during the day or for vacation during the summer, an indoor temperature of 80 degrees can save energy until you return and lower the temperature.
If it's 80 degrees outside, and your thermostat is set to 78 degrees, it shouldn't run as long as it would if it were set to 72 degrees. In either scenario, however, the unit should reach your desired temperature – typically within 15 or 20 minutes – and should cycle off for at least seven to 10 minutes.
Here's the thing: It's normal for your AC to run continuously during hot summer months. You see, on extremely hot days—we're talkin' high 90s to 100s—your system needs to keep up with the incoming heat. To do that, it will run longer in order to maintain a constant, desired temperature in your home.
When things are working right, your central air conditioner should run for 15 to 20 minutes and then turn off for a few minutes. It will do this two or three times every hour. It may run longer when it's sweltering outside.
While you might be tempted to simply turn the AC off, it's actually better to adjust the temperature several degrees higher, by about 7-10 degrees. By installing a programmable thermostat and making this simple adjustment you can potentially save as much as 10% on your energy bill.
It's true that air conditioners do have limits when the outside temperature is extreme. This means that your air conditioner may be able to keep your home at 77 or 78 degrees when it is 104 degrees outside.
Just because the outdoor temperature is above 100, the Ideal temperature to set your AC unit to doesn't change — it's 78 degrees. Higher temperatures in the home are to be expected when the weather is hotter than usual, but your thermostat can still be set the same as if it were a lower temperature outside.
Most air conditioning systems can only handle a 20-degree difference between the outside and inside air temperatures. If it's 80 degrees outside and your thermostat is set to 70, your unit should have no problem.
If it's 90 degrees outside, most people would set their AC to a perfectly comfortable temperature of 68-72°F.
Keeping in mind both energy efficiency and comfort, the best thermostat settings for summer are 76° when you are home, 80-85° when you are away and 72° at night. Then use ceiling fans in the rooms you are in to feel up to 4* cooler. Here's more on why these thermostat settings are the best.
If you set your thermostat in the 80s, the air conditioner won't run enough to effectively dehumidify your home's air. Here in the Tennessee Valley, we have extremely humid weather in the summertime. If your thermostat is set at 80+ degrees, then the humidity inside of your home can easily get up above 70%.
Air conditioners shouldn't generally work all the time unless the thermostat is set to “fan on” (inadvisable). A correctly sized and well-maintained AC system should run for 15 to 20 minutes, two or three times every hour—with longer cycles in the higher temperatures of summer.
Blocked Airflow
If your AC doesn't receive enough air, circulating cool air will take much longer throughout your home. Blockages can develop at several points in your HVAC system that lead to reduced output and longer cooling times.
Dirty air filters are generally the culprit for most air conditioner problems. If your air conditioner is running all day long but not lowering the temperature at home, check your air filters. If they are dirty, simply swap them out for new ones.
As long as you are staying comfortable, your home is reaching set thermostat temperature on very hot days and airflow from vents is normal, and your energy bills are about the same as they were last year – there's likely not a problem.
Once the AC completes a cycle of about 15 and 20 minutes, it should remain off for 7 to 10 minutes. This helps it cool off before starting another cycle. The stops happen 2 to three times per hour.
Here are the brass tacks: Your air conditioner is the most efficient when it's running at maximum “speed” for a longer period of time, rather than short cycles in and out of “maintenance” temperatures.