Should I Use My Thermostat’s “On” or “Auto” Setting?

Thermostats come with a number of different customization options that go beyond just controlling the temperature in your home. One option found on almost every thermostat is the fan “on” or “auto” switch. Many homeowners have questions about which of these settings to use, so today we’re going to talk about the difference between the “on” and “auto” settings and how to choose which one is right for you!


Thermostat fan “on” or “auto” setting: what’s the difference between the two?

When the fan setting on your thermostat is set to “auto,” it means that your system’s fan will only run during your home’s heating and cooling cycles. Once the desired indoor temperature is reached, the fan shuts off until the next cycle.

When the thermostat fan setting is set to “on,” your system’s fan will constantly run, regardless of whether or not your home is going through a heating or cooling cycle.

What are the pros and cons of the fan “on” or “auto” settings?

The “auto” setting.

  • Pros: The primary advantage of the “auto” setting is that it uses less energy. Because the fan only runs when your home is in a heating or cooling cycle, there are times when the fan is completely off and doesn’t consume any energy.
  • Cons: The main problem with the “auto” setting are that it goes through many stops and starts which can wear on the fan over time and lead to increased repair costs. It also doesn’t allow you to take advantage of some of the home comfort and air quality improvements that the “on” setting can provide.

The “on” setting.

  • Pros: When your fan is constantly running, air is always cycling through your filter. This allows for better air quality because particles are being removed from your air at all times. In addition, the “on” setting more evenly distributes conditioned air throughout your home, which helps minimize hot and cold spots as well as improve comfort levels.
  • Cons: The main problem with the “on” setting is that your fan is always using energy, which will increase your monthly utility bills.

Variable speed air handlers provide a compromise between the “on” and “auto” settings.

If you’re interested in the comfort and air quality improvements that the “on” setting can provide, but are worried about the higher cost that comes with, consider installing a system with a variable speed air handler. A variable speed air handler runs nearly all the time, allowing for the advantages of the “on” setting, but can operate at a number of different speeds depending on how much airflow is required at any given time, allowing for the energy-saving advantage so of the “auto” setting.

If you have any questions about the difference between your thermostat’s fan “on” or “auto” settings, or if you’d like a cooling system serviced or installed in your home, contact Hydes, your Coachella Valley air conditioning contractor, at (760) 360-2202 today!