Running Your AC Fan 24/7? Here's Why You Should Stop

Air circulation is good. It's what happens when you turn on a ceiling fan. The movement of air across your skin helps you cool off on a hot day. Combined with AC, moving a little air around can go a long way toward helping you feel comfortable.

Unless you're running your AC fan when the system isn't cooling. That will probably make you less comfortable, not more.

If you're running your AC fan 24/7, you should probably stop. You'll usually feel cooler if you let the fan turn off between cooling cycles. Why? Because when the AC finishes a cooling cycle, the unit's fan isn't just circulating air.

It's increasing humidity inside your home.

Your thermostat has two different settings for AC.

To better understand the issue of running an AC fan 24/7, start by looking at your thermostat. Most thermostats provide options for "Auto" or "Fan" whether you're in cooling mode or heating mode.

In the winter, you can do as you please and it probably won't make a difference. Do you like to run the fan in between furnace cycles? No problem. Leave it on.

But you really shouldn't use the "Fan" setting in summer. You'll probably end up using your air conditioner more than you want to, running up your energy bill, and fighting an uphill battle against indoor humidity.

Here's how running the AC fan increases humidity

Consider what's going on as air moves through your air conditioning system. The system's fan brings air into the indoor unit, where it passes over the cool evaporator coil. Heat and humidity are removed as the conditioned air is pushed back into your home by the same fan.

Ok. All good so far. Now let's remove the cool evaporator coil from the picture.

If you keep running the fan after the system finishes cooling, air is still passing over the coil. The problem? The air is moving over the coil and, since the system is no longer removing moisture from the air, the air is actually picking up humidity from the coil as it reenters your living space.

If you're running the fan while the AC is off, you're literally blowing moisture back into your home.

You see, your air conditioner is really good at extracting moisture from the air. But that moisture condenses on the evaporator coil and a lot of it is still there at the end of a cooling cycle. Reintroducing the humidity into your home is counterproductive. It makes the air more stickier, as a result, makes you feel hotter.

You might end up running your AC more often as you fight against the rising humidity!

The solution? Change the setting from "Fan" to "Auto." Now the fan will only run while the AC is on.

But if you like running the AC fan all the timeā€¦

Look, we know you might like to feel that moving air coming through the vents. For those of you who just can't kick the habit, there are three options:

  • Set the AC to "Auto" (not to "Fan") and keep your ceiling fans on. You'll get the sensation of moving air whenever you walk into a room.
  • Get a variable speed air conditioning system. Unlike standard ACs, which turn on to cool your home and turn off at the end of a cycle, variable speed systems ramp up and down to match your exact cooling needs. During the summer, they run pretty much all the time at a low speed, do a fantastic job of removing humidity, and offer superior energy efficiency.
  • Get a whole-house dehumidifier. This piece of equipment, which uses your HVAC system's ductwork, turns on any time the humidity rises beyond a set threshold. You can keep running the AC fan because the dehumidifier removes the extra humidity. Just be sure it's installed the right way.

Everybody likes cool, dry air. But running the AC fan all the time only adds back the moisture your AC worked so hard to remove. Change the setting to "Auto" and see if you agree with us!

And if you're having trouble managing humidity in your Atlanta home this summer, our team is always ready to help. Just give us a shout!