AC Float Switch: A Complete Guide ( What Is It & Pros & Cons)

While air conditioners have been around for a long time, most people don’t really know what components are inside an ac. A float switch, for example, is a small component that aids in the prevention of water damage.

Despite its small size, the float switch plays an important role in an air conditioner and an HVAC system. That is to say, it is beneficial for you to understand it.

This post has included almost all the information you need to know about an AC float switch. Let’s dive in!

What is an AC float switch?

The AC float switch (also known as the safety switch) is a water level sensor that can alarm the ac to shut off when an overflow happens.

Aside from cooling the air, an air conditioner will also dehumidify it. Excess moisture in the air will condense into water droplets, some of which will collect in the drain pan.

However, if the drain pan becomes full of water, an overflow can occur, resulting in a variety of negative consequences. To avoid this issue, an AC float switch is used.

If you have a portable air conditioner, you can manually drain the water. When the pan is full, the float switch will activate, shutting down the machine and alerting us to empty the pan. Hisense models, for example, will display an E5 code.

Other types of air conditioners use a hose to drain the water. The water in the drain pan will drain outside via the hose. The pan will never fill up, technically.

The drain hose, however, can become clogged over time, causing the water to return to the pan. In this case, the ac float switch can detect rising water levels and alert the device to shut down.

Where is the float switch located?

The location of the float switch varies according to the types and brands of your air conditioner and HVAC systems. 

Some air conditioners come with a secondary drain pan, and some don’t. If your ac has a secondary drain pan, the float switch will locate there.

Otherwise, the drain pipe will be connected to the float switch. When the water level in the drain pipe rises, the float switch activates and the machine turns off.

Benefits of using an AC float switches

After reading the sections above, you may have a basic idea of why your ac needs a float switch. This section will talk about more benefits you will get from using it.

Prevent water damage

Water damage and ruining furnishings can occur if the water overflows and leaks all over the floor. Everyone who has dealt with water damage understands how aggravating it is.

It is possible to prevent water damage by using an ac float switch. When you are not at home, you can be confident that no water will leak through the ceiling.

Save money 

Repairing the carpeting, flooring, and walls could be very expensive. Since AC float switches can prevent water damage, they save you thousands of money on preparing your house.

Good for your health

If your ac leaks water, the excess moisture will promote mold growth and make your ac give off a musty smell

Mold spores can find a residence in your body and cause an array of complications. For instance, it can trigger allergic reactions, the difficulty of breathing,  and lung infections.

Extend the lifespan of your AC

Electrical components could be damaged whenever there is a leakage.Because the float switch prevents the machine from leaking water, it protects the electrical components and thus extends the machine’s lifespan.

Drawbacks of using an AC float switches

Strictly speaking, AC float switches don’t have any huge shortcomings. But there are two things you should keep in mind before installing this safety switch.

Spend some extra money 

Some HVAC systems don’t come with an ac float switch. In this case, you need to purchase it separately and get it installed. Luckily, it is not very pricey.

Get stuck

The stuck float switch is a common cause of a leaking air conditioner. The dirt and grime accumulated over time can make it malfunction, and your machine can’t stop working even if the drain pan is full.

Don’t be too concerned! You can clean out the buildup easily.

Float switch vs. wet switch: what’s the difference?

As technology advances, two types of switches detect water levels. The other type of safety switch is called a wet switch. 

A wet switch costs a bit more than a float switch. However, it tends to be more responsible. A drop of water can activate it. Meanwhile, it is easier to install.

Some HVAC technicians will advise you to install both to avoid the problem as much as possible. 

How to make sure your AC float switch function well?

Now that you have a basic understanding of an AC float switch let’s investigate the state of the float switch in your ac. 

If there is water inside the secondary drain pan, you should first address the drainage issue. If not, find the switch and see if the float arm moves smoothly.

Finally, lift the float arm for a few seconds to see if the machine will shut down automatically. Remember to replace the float arm to allow the ac to back to work.


The float switch on the ac unit is important for keeping your machine in tip-top shape. With its assistance, you can avoid most leaks and overflows that could cause damage to your home. 

It can become stuck over time. As a result, you should check its status on a regular basis.

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Liz Yang is the founder of Airsmartly. She has been working at home for a few years and realizes that the performance of the HVAC system plays such an important role in our life. She has tested a lot of products in person, like humidifiers, air purifiers, dehumidifiers, and ACs, and wants to share tips about using or troubleshooting these products with you. Her uncle is an HVAC expert with over 30 years of experience in the field, and often offers assistance when she is unsure how to handle a situation. He is also in charge of reviewing the articles on this site.

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