Should You Set Your AC Fan to “On” or “Auto?”

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Understanding how to set your thermostat is one of the most important things you can do to reduce energy costs and avoid overworking your unit. 

The temperature setting is easy enough to figure out. However, customers often get confused when it comes to the fan settings. Should you set your AC fan to “on” or “auto?” What’s the right setting? 

Unfortunately, there’s not a simple black-and-white answer. 

It depends on your specific system and the unique needs of your home. Not sure? Schedule a maintenance check and we can help you figure it out! 

A digital thermostat

Should You Put Your AC on Fan or Auto? Here are the Pros and Cons of Both 

Setting your AC fan to “on” will ensure that the unit runs constantly – regardless of the temperature setting or the temperature inside your home. 

Now, this doesn’t necessarily mean that your AC unit will constantly cool the air. It just means that the fan will continue circulating the air throughout your home regardless of whether the unit is running a cooling cycle or not. It depends on your specific system. 

Meanwhile, setting your AC fan to “auto” means that your system will turn on, cool your home to your desired temperature, then shut off when that temp is reached. It will cycle on and off to maintain the thermostat settings. 

It might seem like “auto” is the best choice if you want to keep your home cool and avoid unnecessarily high electric bills but that’s not always true. Here’s how to decide what’s right for your home. 

Pros of Keeping Your AC Fan Set to “On” 

Setting your AC unit to “on” can provide a few benefits you might not be aware of. 

  • It can improve indoor air quality. 
  • It can reduce uneven temperatures in different rooms. 
  • Less frequent stops and starts could prolong the life of your system. 

When you run your fan constantly, it will keep the cooled air circulating throughout your home. The constant blowing will give the cool air a chance to reach further corners of your house where it might normally be too warm. 

Running your fan 24/7 also means that more air will pass through your filter. In other words, it can improve overall air quality. Keeping your fan “on” might be a smart choice if you have several pets or someone in your home suffering from 

  • Allergies 
  • Breathing conditions 
  • Immune system problems 

Finally, leaving your AC fan “on” can put less stress on the blower motor. Since it’s not stopping and restarting dozens of times each day, it’s less likely to break down. 

Cons of Keeping Your AC Fan Set to “On” 

Constantly running your AC fan can get costly, especially if there are bigger problems lurking in your system. 

  • You’ll need to replace your air filters more often. 
  • You could end up blowing more hot air into your home. 
  • It can skyrocket your electric bill. 
  • It can overwork your coils. 
  • Your air might feel more humid. 

Running your AC constantly means you’ll need to bump your filter replacement to once or twice per month, depending on your home. That cost can add up quickly. 

Running your AC unit can also drive up your energy bill – sometimes by over $50 each month. If your system is already running inefficiently or your ductwork is leaky, it will pull more hot air into your home and boost monthly bills even higher. 

Finally, constant airflow can overwork your coils. Your system won’t be able to dehumidify the air as efficiently. Coils will need to be cleaned and replaced more often. 

Not sure about the health of your condenser or evaporator coils? Schedule a 32-Point Tune-Up so our experts can take a look! 

Pros of Keeping Your AC Fan Set to “Auto” 

In most cases, setting your AC fan to “auto” is the ideal choice. 

  • It’s the most cost-effective setting. 
  • You won’t have to change your filter as often. 
  • Your home should be less humid. 

Since your system will only run when it’s 100% necessary, your energy bills will stay as low as possible. Upgrading to an innovative energy-efficient system can lower your costs even further. 

Less air flowing through your system also means you won’t have to replace your filters quite as often. Although you should still use high-quality filters and replace them every 60-days or so depending on your home’s unique needs. 

Running your AC fan on auto also means that less air will pass over your evaporator coils. They won’t get overworked, and they’ll be able to dehumidify the air much more efficiently. However, your coils should still be inspected and cleaned once a year as part of a 32-Point Tune-Up. 

Cons of Keeping Your AC Fan Set to “Auto”

Although “auto” is generally the best setting, it doesn’t come without a few downsides to consider. 

  • The temperature may not be even in every room. 
  • Frequent starts and stops can overwork the fan. 
  • Your home may be warmer than you’d like. 

Keeping your AC fan set to “auto” can mean living with uneven temperatures around your home. 

For example, a bedroom in direct sunlight might not cool down completely. If air from a vent blows directly onto your thermostat, that could trick your system into shutting off before the home reaches your desired temperature as well. 

Lastly, setting your system to “auto” means that it will turn on and off dozens of times each day. These frequent stops and starts could overwork your fan’s blower and lead to a breakdown. 

Not Sure About Your AC Settings? Call the Experts for Air Conditioning Services! 

Every AC system is unique. Our expert technicians at Home Comfort USA will investigate your unit, ductwork, and thermostat to provide you with a custom recommendation. 

Many problems mentioned above – like uneven temperatures or high humidity – signal a larger issue with your unit. During a maintenance check and 32-Point Tune-Up, we can identify and replace faulty parts and clear out grime before they turn into costly emergency repairs

In other cases, your thermostat might be outdated, or your system might be due for an upgrade. While a new AC unit might cost more up-front, it can save you hundreds of dollars each year in energy bills. An efficient AC system is an affordable system. 

Schedule an appointment for a 32-Point Tune-Up with our experts at Home Comfort USA or call 888-462-0089.

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