In Florida, we know and dread the thick blanket of warm air that hits us when we open our front door.
And we also know that humidity should NOT be something we feel in our own homes.
But you might be inviting humidity into your home without even knowing it.
By setting your AC thermostat fan to ON instead of AUTO.
Let’s take a closer look so that you know how and why to avoid this common mistake.
ON and AUTO are the two settings for your AC fan.
The difference between ON and AUTO boils down to when the fan blows:
So, what does that have to do with humidity?
To better understand how a fan affects indoor humidity, let’s first look at what the AC fan does and where it’s located.
If you have a split system AC, you actually have two fans in your AC unit: one fan for your outdoor unit and one fan for your indoor unit.
But for the sake of this article, we’ll only be looking at the fan on the indoor unit (we’ve pointed it out in the picture above).
Your fan sits directly behind the cooling coils and is responsible for pushing air through the ducts and into your home.
Basically, the ON setting is not allowing your AC to properly dehumidify your home.
That’s right, your AC actually has 2 jobs:
Here’s how your AC normally dehumidifies your home: When warm air from inside your home is pulled into your indoor unit, it passes over very cold refrigerant coils.
Those cooling coils absorb the warmth and moisture from the air. Then that cold, dry air is pushed back into your home.
What happens to the moisture? Where does it go?
Well that completely depends on the setting of your fan:
If the fan is set to AUTO, that moisture collects and sits on the refrigerant coils. And once the fan shuts off in between cooling cycles, that moisture has time to slide off the coils and drain away outdoors.
But if the fan is set to ON, the moisture on the refrigerant coils does not get the chance to drain away. Because the fan blows constantly, most of the moistures evaporates and gets blown right back into your house!
So, quick recap:
Yes, the ON setting should never be used if you want to prevent high indoor humidity.
But there are still some situations in which the ON setting comes in handy.
Here are a few ways the ON setting can be helpful:
Posted in: Tips