How Many Hours Should AC Run Per Day?

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Air conditioners have the most crucial role in keeping your home comfortable and cool throughout the scorching summer months. 

When air conditioning equipment isn’t functioning correctly, it can make your life miserable. Plus, AC units can be tricky to maintain, and in some cases, you might be completely unaware of a persisting problem– unless you know what to look for. 

Luckily, air conditioning cycles are an excellent indicator of your AC system’s health. To learn what you should look for, listen to, and feel for, continue reading this detailed guide on how long your AC system should run!

a person using a remote to turn on the wall-mounted AC

How Long Should An AC Unit Run For?

Ideally, your air conditioner should run for 15-20 minutes with moderate outdoor temperatures. The AC unit should typically complete a cooling cycle two to three times per hour (as necessary).

However, several factors can impact the number of cycles in a day and the length of time the system runs per cycle.

What Factors Affect The Run Time?

A person adjusting the temperature of an AC unit

Several factors impact how often and the length of time your AC unit runs. The top factors include:

Oversized unit 

If your AC unit runs for short periods of less than 15-20 minutes and turns on and off more than four times per hour, your AC unit is likely too large for your home. This is called short-cycling, where the unit cools your home too quickly. When this happens, the AC unit cannot dehumidify your home as efficiently as it should, making you feel hot and sticky. 

Undersized unit

On the other hand, if your air conditioner is too small for your home, it won’t be able to make your house cool and comfortable. Undersized AC units tend to run for long periods while never reaching the setpoint on the thermostat. If your AC unit has run for twenty to thirty minutes or longer with no temperature change, your AC unit may be too small for your home. 

Try this calculator to help work out what size air conditioner you need.

High temperatures

Your AC unit will likely run longer than usual when the weather is sweltering. Normally, this is not something you should be concerned about. 

Size of your home

The size of your home plays a vital role in cooling cycles. Larger homes take longer to cool than smaller ones, especially those with inadequately sized AC units. 

Insulation quality

Insulation is just as important in the summer as in the winter. Good insulation will keep the air inside your home warm in the winter and cool in the summer. If you have insufficient insulation, your conditioned air will leak outdoors, counteracting your AC unit’s hard work. Of course, this causes it to run longer. 

Condition of the unit

Unfortunately, all AC units age over time. Although some brands last longer than others, they will eventually become less efficient as it ages. However, if you take care of your air conditioner and perform routine maintenance, it will maintain good efficiency for much longer. However, if you skip maintenance and service, it will quickly become inefficient and run longer while struggling to keep up with cooling demands. 

Thermostat setting

The setting on your thermostat is a critical factor in how long your system runs. The lower the setting, the longer the unit will run to bring your home to that temperature. It’s intuitive that if you set your thermostat to 61ºF, your AC unit will run longer than if you put it to 71ºF if everything is the same. 

Learn More: Common Air Conditioning Problems

What Is An Air Conditioning Cycle?

A person checking an air conditioning unit

Now that we know how long your air conditioner should run, let’s explain the air conditioning cycle to understand why your AC unit should not run 24/7, even in the hot summer.

An air conditioning cycle is the amount of time the unit runs to cool your home. Throughout the summer months (or year-round if you live in a hot climate), your air conditioner will turn on and off to keep your home cool. 

If your thermostat measures a temperature above its setpoint, it will turn the AC unit on to lower your home’s temperature. How long it runs depends on how far it is away from the setpoint and the brand and model of your air conditioner. 

Note: If you have the thermostat set to “fan on,” it runs the blower fan constantly– even when the AC isn’t cooling. This is inefficient and not ideal in the summer months; we recommend leaving the fan set to “auto.” 

When your air conditioning system is cooling, consistent off and on cycles throughout the day are entirely normal. Typically, it should not run all day or for very long periods. 

Abnormal AC Cycles

Air conditioning units should remain within the outlined parameters, if not reasonably close. Too long or too short of cycles can indicate several issues with your air conditioner. 

Short cycles usually point to an incorrectly sized unit, dirty coils, electrical problems, thermostat errors, condensate drain blockages, or a clogged filter. 

When your air conditioner runs for ten minutes or less several times per hour, it may cause permanent damage to the compressor, the heart of the AC unit. 

On the other hand, long cycles are equally bad. Lengthy run times may indicate an improperly sized system, incorrectly sealed or sized ductwork, dirty filters, or low refrigerant levels (typically caused by leaks). Long cycles could also cause your AC unit to break down sooner than it usually would. 

However, it’s important to note that extremely high temperatures can cause longer run times– remember, your AC unit will have to work longer to remove heat and bring the temperature down during scorching days. 

Air Conditioner Run Time

On average, your air conditioner should run for 15 to 20 minutes with 2-3 cycles every hour. However, how long it runs and how many cycles it completes depends on various factors like the size of your home, the outdoor temperature, your home’s insulation, and the thermostat’s setting.

If your air conditioner is consistently running for longer than 20 minutes or cycling more than three times an hour, you may have an issue with your AC unit that you should have addressed by an HVAC technician.

About The Author

Jonathon is a mechanical engineer with over ten years of experience in the HVAC industry. He has hands-on experience with all types of HVAC systems.

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