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Why You Shouldn’t Run Your AC Fan 24/7


Good air circulation is an essential part of keeping your home comfortable. On a hot day, the effect of air moving over your skin from a ceiling fan, combined with the cooling action of your AC, can significantly enhance comfort. However, there are ways to achieve this while also saving money as a homeowner.

One common mistake that homeowners make is running their AC fan constantly, even when the cooling system isn’t in operation. Although this may seem like it would increase comfort, it can actually make your living environment less comfortable and increase your energy costs.

Your AC fan could be increasing humidity in your home

When your air conditioning system is actively cooling, it’s doing two main things to the air in your home: it’s reducing the air temperature and it’s dehumidifying the air.

As warm, humid air from your home is drawn over the cold evaporator coil of the air conditioning unit, two things happen: the air cools down and the moisture in the air condenses onto the coil, removing humidity from the air. The cooler, drier air is then circulated back into your home.

However, when the cooling cycle finishes and the AC is off but the fan is still running, the dynamics change. The evaporator coil, while no longer actively cooled, is still wet from the previous cooling cycle. As the fan continues to draw air over the wet coil, it doesn’t cool the air anymore but it does pick up moisture from the coil.

That means the air being circulated back into your home by the fan isn’t being cooled and, in fact, has increased humidity. So, by running the fan when the AC is off, you’re blowing moisture-laden air back into your home, which can make the indoor environment feel warmer and more humid, counteracting the effects of the AC’s previous cooling and dehumidifying cycle.

Your thermostat settings improve efficiency

Understanding your thermostat settings can go a long way in helping you save money and maintain a comfortable home. Most thermostats have an “Auto” and a “Fan” setting for both cooling and heating modes. Using the “Auto” setting in summer will help you save on energy costs and manage indoor humidity more efficiently.

To illustrate why running the AC fan constantly can be a costly mistake, consider what happens when air moves through your AC system. The system’s fan draws air into the indoor unit, where it moves over the cool evaporator coil, reducing heat and humidity before it’s circulated back into your home. However, if you continue running the fan after the system finishes cooling, the air picks up humidity from the coil, reintroducing it into your living space. This not only makes your home feel hotter and more uncomfortable but might also lead you to use the AC more, increasing your energy costs.

If you enjoy having the AC fan running continuously, here are some cost-effective alternatives:

  1. Set the AC to “Auto” and use your ceiling fans: This can give you the sensation of moving air whenever you walk into a room and is a more energy-efficient choice.
  2. Opt for a variable-speed air conditioning system: Unlike standard ACs, variable-speed systems adjust their output to your exact cooling needs. They operate mostly at a low speed, offering superior energy efficiency and humidity control.
  3. Install a whole-house dehumidifier: This appliance uses your HVAC system’s ductwork and turns on when the Florida humidity exceeds a set threshold. With a dehumidifier, you can run the AC fan without worrying about the extra humidity. Ensure it’s installed correctly for maximum efficiency.

By making the shift from the “Fan” to “Auto” setting, and considering the alternatives above, you can enjoy cool, dry air while also reducing your energy costs. Enjoy the comfort of your home without the high bills!


When you work with Tony Kelly Heating & Air Conditioning, you can trust that you are working with professionals who are friendly, efficient, and entirely committed to you. We have gained a stellar reputation among our clients in Tallahassee, FL and the surrounding areas since we first began in 2000. We strive to build lasting relationships with our clients and maintain 100% client satisfaction with each air conditioning and heating service provided. We offer a client satisfaction guarantee and will ensure that you are completely happy with your service each time. Call or text us now at 850-792-4488 to learn more about how Tony Kelly Heating & Air Conditioning can assist you.

published on Wednesday, May 31st, 2023