The sound of the AC kicking in on a hot summer day brings joy to a homeowner’s ears.

But what if your AC just won’t turn off? Is it supposed to run all day and night?

Homeowners wonder exactly how long should an AC run after reaching the temperature they desire.

When a home feels comfortable, the AC should turn off. But when it doesn’t stop, you may have a problem.

Keep reading to learn more about how long an AC cycle should last and what it means when your AC runs constantly.

How Long Should an AC Run

The warmer the outside temperature, the harder your AC must work to keep your home cool.

Thus, it only makes sense that summer temperatures will cause your AC to run almost constantly.

On milder days, though, when you’re just beginning or ending your warm season, the AC should cycle on and off approximately every 15 minutes.

Four things affect the cycling of your AC system:

  • Weather and outside temperature
  • The size of your AC unit
  • Your home’s insulation quantity and quality
  • If your AC is working properly

Warmer temperatures will logically cause your AC to work for longer periods of time.

Furthermore, if you have a smaller AC unit, it will have to run longer for you to achieve the desired temperature in your home.

If you have an adequate amount of quality insulation, your AC won’t have to work as hard either.

What Makes My AC Run Longer?

Your AC will run longer on a hot day, as previously mentioned.

If your humidity has crept up, the AC will run longer and more frequently as well. But other factors will cause your AC to run longer.

Thermostat Settings

Logically, a thermostat set to 65 degrees will cause an AC to run longer than a thermostat set to 72 degrees.

While you may love a cool house, setting your thermostat even a couple of degrees higher will give your AC a break and save you some electricity in the process.

AC Unit Size

One might believe that bigger is better in the world of air conditioning.

If your AC won’t shut off, you may have a unit that’s too small for your home.

But a unit that’s too big can also cause problems.

Your AC should run for about 15-minute cycles.

If you hear your AC shutting off in shorter increments, then you most likely have an AC that is too big for your home.

When the AC kicks off after ten minutes, it may adequately cool your home, but it will not adequately dehumidify your home.

Experts call this problem short-cycling, meaning that the AC runs in shorter than essential cycles.

So you may feel sticky and hot even though you have cold air coming into your home.

An HVAC technician can give you a recommendation on the right size AC for your home.

AC Unit Quality

Like all things, air conditioners have a duration life. If you care well for your AC, it will last as long as and sometimes longer than its expected lifespan.

But if you neglect your AC, it will slowly start breaking down and it ultimately will not cool your home well.

You should have your AC inspected every year by an HVAC expert.

They can help detect leaks and other small problems the untrained eye cannot see.

When you do not care for your AC unit, it will work harder to achieve the desired results.

You will also spend more on your energy bill as your AC stays on for longer amounts of time.

Home Size

If you have a large home and a smaller unit, your AC will logically run for longer periods of time.

There are a few hacks that you can employ to help keep your home cool and yet keep your AC from running all the time.

First, you can strategically cool only certain areas of your home.

Start by shutting the doors to the rooms you do not spend time in, like your guest room.

You can also close the dampers or vents in the rooms that you do not use to redirect cool air to the main part of your home.

Insulation Quality

Insulation keeps your home appropriately warm and cool.

If you have poor insulation, then your AC will work harder in the summer, and your furnace will work harder in the winter all to help you maintain a comfortable temperature.

Insulating your home will cost money, but that cost is a one-time fix.

When you do not have proper insulation, you will pay more than you need to every month for a high energy bill.

Thus, proper insulation can actually save you money in the long run.

Dirty Air Filters

When your AC is running constantly but the thermostat temperature reading doesn’t move, you may have a clogged air filter.

A dirty air filter prevents air from moving efficiently from the AC to the vents.

On the positive side, it’s pretty easy and inexpensive to change the filter in most homes.

A clean filter will allow air to circulate more easily through your system, and your AC will cool your home more efficiently.

Dirty Coils

A dirty coil will prevent air from flowing freely into the air conditioning unit.

As a result, your unit will run constantly and futilely, trying to cool your home but unable to do so because of dirty coils.

To keep the coils clean, call an HVAC expert once a year to tune up your AC.

Experts can see and remove the dirt and debris from around the coils.

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.

Always check your air filter first and begin researching to see if you have the right size unit for your home.

Then call in the experts. An experienced HVAC technician will inspect your unit and pinpoint any problems you may have.

Is your AC running for longer periods of time than normal? Or do you hear it short-cycling regularly?

If so, give us a call. We are committed to providing the best service and customer satisfaction in Phoenix and the East Valley.

Our new installs comes with a Lifetime Workmanship Warranty to assure that we do the job right the first time.

Satisfied customers have been coming back to us for over 70 years.

Contact us today, and let us help you stay cool.


Is your AC unit working the way it should? If not, call the top rated air conditioning company in AZ for AC Maintenance or AC Replacement. The team at Scottsdale Air Heating & Cooling has been serving the valley for over 75 years! Call 480-945-7200 or request service online! …*Yes, We DO offer Financing Options.

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