This summer – whether you have a manual or smart thermostat  from ClimateCare in your home – chances are you’ve wondered whether the air conditioner fan should be set to ON or AUTO.

It’s a common question many homeowners have.

After all, some people swear by the ON setting, while others are convinced AUTO is the way to go.

In order to properly answer the question of should the thermostat fan be ON or AUTO, you first need to know the differences between each setting.

What is the ON setting?

Thermostat fan setting on

In short, ON means on. The fan is constantly blowing.

You’ll want to use the ON setting when it’s absolutely blistering out and you’re absolutely desperate to keep cool. The fan in your home cooling system will keep running until you turn it off.

(The same idea also applies to your furnace in winter).


  • Air is always flowing through your home’s air filtration system, which ensures your indoor air quality is clean.
  • Fewer stop-and-start cycles for your AC fan (this can help extend its lifespan).
  • Cool air is evenly and equally distributed into all rooms throughout your home (no more uneven hot-and-cold spots in the house).


  • Because the fan is always running, you’ll be cooling your home even when it’s not necessary. That can lead to higher energy bills.
  • You’ll be changing your HVAC product filters more often.
  • Because the fan is always running and working, there’s a greater chance it’ll break down and require air conditioner repairs.
  • Increased humidity in the home.
  • If the air ducts in your home are older, they probably have “leak points” in them. By having the fan set to ON, you’re always losing some cool air.

What is the AUTO setting?

AC fan auto

AUTO is short for automatic. The fan only turns on when cooling or heating (in winter) is required.

If you can tolerate most of the summer heat – save for the absolute hottest of days – you’ll want to use the AUTO setting. The AC fan kicks in when needed and stops running when the job is done.


  • Saves energy and lowers your monthly energy bills.
  • Air filters and furnace filters last longer and don’t need to be replaced as often.
  • Greater control over your air conditioner. You specify when the fan turns on (by temperature) and when it shuts off.
  • Better humidity control.


  • Because the fan is always starting and stopping, it’ll probably break down faster than if the air conditioning fan was running in the ON setting.
  • Cool air isn’t delivered evenly through your home, which results in hot-and-cold spots.
  • The indoor air quality in your home may not be as clean and clear as it would in the ON setting.

Thermostat fan ON or AUTO. What’s right for you?


It all comes down to the needs of you and your family.

For example:

  • If you have allergy sufferers in your home, you might want to have the consistent air circulation of the ON setting.
  • On the other hand, if you’re looking to cut down on your monthly hydro bills, the AUTO setting is your best option.
  • Do elderly relatives or parents live with you? The ON setting will keep them comfortable and safe, especially during a heatwave.
  • Not bothered by the summer heat for the most part? Use the AUTO setting to program when the fan turns on and when it shuts off.

Need more info? Looking for advice? Contact your local ClimateCare member

This summer is going to be hotter than normal. That means your air conditioner will be working overtime to keep your family cool.

You want to make sure it runs efficiently and reliably with regular air conditioner maintenance.

After all, you don’t want it breaking down on the hottest day of the year.

Whether you want to schedule a service call, have questions about ON or AUTO, or want to upgrade your current AC, ClimateCare can help.

Find the nearest ClimateCare location to you. When you do, send your comments. They’ll get back ASAP with the answers you need.

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