What Is AC Float Switch & Why It Is Important?

Dominic Mitton
By Dominic  • Reviewed by Ben  • Updated:   October 26, 2023
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One of the most important safety features of any AC unit is the float switch.

While many people don’t know what it does or where it is located, I can assure you that it’s part of every unit and it’s not for no reason – it ensures your air conditioning system will stay safe and prevent serious damage.

In this article, you’ll learn more about the AC float switch, where it is located, and how you can test it to make sure it’s working properly.

Let’s jump straight to it.

What Is An AC Float Switch? 

The AC float switch is an electronic water sensor that gets triggered if it detects overflow that the drainpipe can’t resolve on its own.

Essentially what the AC float switch does is it automatically shuts off the whole unit if it detects a clogged drain or water leak. 

By doing this, it prevents much larger leaks or serious damage to the unit.

You can learn how to quickly fix AC water leaking inside.

Where Is The AC Float Switch Located?

AC float switches can be located in different places depending on the model you have.

This depends on the orientation of your unit.

Usually, it’s located in the condensate drain line and condensate drip pan.

If your unit is placed horizontally, the float switch will be inside the secondary drain pen.

While vertically placed units usually have a float switch inside the drainpipe. Also, some older models don’t have the secondary drain pen, so the float switch is located in the drainpipe as well.

However, some smarter air conditioners have more float switches to eliminate any risk of water leaks.

Purpose of AC Float Switch

While you should know by now what is the float switch, let’s explain it a bit deeper.

When your unit is working, it will collect moisture from the air, but smaller amounts of moisture will be left behind.

To ensure that this water is collected too, every unit must have a drain pan.

Because of this process, sometimes an overflow of moisture in this drain pen causes water to spill out of the unit. While it might sound non-harmful, this might accelerate mold growth in your unit which can even cause health issues.

That’s where the AC float switch does its thing.

When the water collected in the drain pan goes above safety levels, your unit will automatically shut off and prevent any further damage.

The Best Way To Test an AC Float Switch

I have tried almost every possible way to test the AC float switch.

In my opinion, the best way is to plug the drain downstream of the float switch and keep your unit running until the float switch trips. This shows you how your float switch would react if it was a real scenario.

If you don’t have patience with this method, you can always pour water into the condensate drain pipe and see immediately how the float switch performs.

I’m not a big fan of this second method because you can miss a small, yet important water leak in your system.

A lot of newer air conditioners have a test mode button on the float switch, simply press it and it will test it.

If you’re worried about your unit’s water leaks, I encourage you to take a look at 6 common reasons why your unit is leaking water.

Hey there! I am Benas, the founder and content editor at Home Caprice. Thanks for reading the article. I hope you were able to find what you were looking for. I and my team are here to simplify heating and cooling for everyone. Please have a look at the About page for more details about our website and feel free to check out our editorial process.