Fan On vs. Auto: How Should I Set My Thermostat?

Many homeowners here in the Coastal Bend have questions about their cooling systems. One of the most common inquires has to do with setting the thermostat. Should the fan be switched to “Auto” or to “On?” What’s the difference between the two anyway? These questions will be addressed in this post.

Fan “On” vs. “Auto”

The two most basic things that an A/C does is cool and move air. Setting the thermostat to a specific temperature controls the cooling of air, while adjusting the fan settings allows it to flow throughout the home. A fan switched to “On” runs nonstop, even when the air isn’t being cooled. When the fan is switched to “Auto,” though, it only moves air when the cooling or heating cycle kicks on.

Pros and Cons of Setting the Fan to “Auto”

The primary benefit to setting your fan to “Auto” is energy savings. Your filters will also become clogged less often, decreasing the need to change or clean them. Finally, fans set to “Auto” can control humidity much better. The downside to setting the fan to “Auto” causes the fan to cycle on and off frequently, which can contribute to wear and tear. However, the pros far outweigh the cons.

Pros and Cons of Setting the Fan to “On”

When you set your fan “On,” your air will constantly flow throughout the home. This can increase costs as the system will use more energy. Running the fan continuously can also reintroduce humidity to the home. When the weather is dry, you may be able to boost A/C efficiency by keeping the fan on for a few minutes after the completion of the cooling cycle, but avoid leaving it on all the time.

The experts at CCAC are happy to answer any other questions you may have about setting the thermostat. We’ve served residents of South Texas  since 1979.

Our goal is to help educate our customers in Corpus Christi, Texas about energy and home comfort issues (specific to HVAC systems). For more information about thermostats and other HVAC topics, download our free Home Comfort Resource guide.

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