FPL Blog



It's all about you

Featured Posts

Take 3 minutes to help your neighbors in need

You can help your neighbors in need right now by visiting www.SupportLIHEAP.org. In less than three minutes, you can contact your members of Congress to urge their support for continued funding for the federal Low Income Home Energy Assistance Program (LIHEAP).      Relief from the heat isn’t always as easy as adjusting the thermostat, […]


Ensuring Reliability

Getting your life back to normal faster after a storm

As president of Florida Power & Light Company, Eric Silagy leads the thousands of employees who bring affordable, reliable power to you every day. He’s raising his family here in the sunshine state, something that fuels his drive to always look for ways to make tomorrow better for all of us. If you’ve experienced a […]


Old Poles Have New Life as Artificial Reefs

If you’re a local diver, angler and anyone who loves the ocean, I’ve got good news. You can now enjoy two new artificial reefs that were created using a donation of concrete FPL poles, right off the coast of St. Lucie County. Consider it  a new take on recycling! One of the things I love […]


Restoring power -- anytime, anywhere

From time to time, you may see an FPL truck parked near your home late at night, possibly even when your power is working just fine. Don’t be alarmed. Our crews work around the clock to restore power, and they may need to work on equipment located near you to resolve an outage in your […]


Energy Efficiency

Students see solar energy in action

Schools across Florida are using our state’s sunshine to help power classrooms and teach kids about clean energy. Through FPL’s Solar Pilot Program, nearly 100 schools and other educational facilities will be getting special solar-panel displays by the end of 2014. While installing solar panels can be out of reach for many Floridians, these facilities […]


Craig Muccio

About "Ask the Energy Expert"

Craig Muccio runs FPL's Conservation Research & Development Program and crunches the numbers to figure out how you can save by managing your energy use.

Your questions on energy-related topics can be submitted anytime to our Ask the Energy Expert blog. Just click here to submit your question, and if chosen, it will be answered here

A/C fan switch – “on” or “auto”? Which saves the most money?

By Craig Muccio

Asked on: August 28, 2014 by Beverly H., Weston

Which A/C fan setting costs more, “on” or “auto?” My friend believes the “auto” setting uses more electricity.

That’s actually a common, but important question. The on/auto fan switch on your A/C thermostat will affect the price you pay to cool your home. The A/C fan circulates the cooled or heated air throughout your home. Setting the fan switch to “on” will make the A/C fan run continuously, 24 hours a day. Choosing the “auto” setting will cause the fan to shut off with the rest of the cooling system as soon as your desired temperature on your thermostat is reached.

Fan “on” costs more
Advice from friends can be helpful, but in this case your friend was mistaken to think that the auto setting used more electricity. Let’s assume your air conditioner normally cycles off 30 percent of the time. In this example, turning the fan switch to “on” will make the fan run over 200 extra hours a month. For a typical size central air conditioner, that would cost you about $8 more each month. Keep in mind, a fan that runs all the time may also wear out sooner.

Another reason to keep it on “auto”
Setting your A/C fan to auto also helps provide better dehumidification. Have you noticed how moisture from the air condenses on the outside of a cold drink on a humid day? Your A/C unit captures moisture the same way, helping your home feel more comfortable. When the fan cycles off using the auto mode, moisture has a chance to drip from the cold cooling coils into the condensation pan and then drain outside. However, when the fan runs all the time in the “on” setting, less moisture has a chance to drip and drain outside. Instead, some gets blown back into the air again.

Some people prefer the feel or sound of the fan running all the time. If that’s you, at least now you know how much that choice will cost you.

Learn how to save even more
During Florida’s hottest months, we want to remind you that you can save five percent on your monthly cooling costs for each degree you turn your thermostat up. Also, our top summer tips can help you save even more.

You can also take our Online Home Energy Survey to get a personalized savings plan filled with energy-saving tips and recommendations. It’s easy, and can save you up to $250 a year.

Did you find this Ask the Expert column helpful? Get more expert energy saving advice by following our Ask the Expert column monthly and remember you can submit your own question.

Leave a Reply

Join the conversation with FPL on ways to save energy and keep your bill low.

Plus, learn how we are constantly working to deliver you reliable service.

Please note that this blog is not monitored 24/7.

For customer service questions: www.FPL.com/contact

To report an outage: www.FPL.com/outage

Your email address will not be published. Required fields are marked *



Comment moderation is enabled. Your comment may take some time to appear.

Comments [6]

  1. JoAnn Turk

    I enjoy your helpful blog "Ask the Expert"

  2. jim y

    For homes that don't have adequate flow to a room, isn't it cheaper to leave the fan on circ rather than turning the thermostat colder?

  3. Ira Cohen

    What if you have an electro static air cleaner

  4. Don Leonard

    Will our chest freezer use more electricity during the summer if it is in a very hot garage or in the airconditioned house where it generates hot air from the compressorn that will increase our cooling cost.

  5. H Lewis

    We use ac for comfort. At night we leave the fan on "on" to circulate fresh air otherwise the air becomes stale and the humidity goes up when the ac cycles off. During the daytime we put the fan on " auto" so the fan does not draw the warm attic heat when the ac cycles off. Again we use ac for comfort but have you made a cost comparison. Give it some thought

  6. Ed Goldstein

    I would agree that a A/C fan operated in the auto position would be a saving. I wonder if your calculation included the added cost of the inrush current each time the fan is called for . I think it may be small however it is an item. I also think a variable drive and 3 phase motor could save a considerable amount over time. The investment could be paid back most likely in the first year. I would suggest that the speed be adjusted according to when the thermostat calls for cooling and when it commands a shutdown reduce the speed for comfortable air circulation.


FPL reserves the right to edit any user submissions to "Ask the Energy Expert" for brevity or clarity. Publication of readers' questions or comments is at the sole discretion of FPL.