Dehumidifier Freezing Up? Here’s What to Do

If your house has excessive humidity, a dehumidifier will help keep the humidity at a proper level. 

However, all that extra moisture has the chance to freeze up into an ice block inside of your dehumidifier. 

What happens when your dehumidifier freezes up and stops working?

In this article, I’ll go over what you need to do if your dehumidifier is freezing up. I’ll also discuss what you need to do to defrost your dehumidifier and get it running properly again.

What to do when your dehumidifier is icing up

If your dehumidifier is freezing up, the first thing you need to do is put it in fan-only mode. Fan-only mode will help defrost your dehumidifier.

How does running the dehumidifier in fan-only mode help defrost it?

When a dehumidifier is in fan-only mode, it will blow room-temperature air through your dehumidifier. As long as your dehumidifier is in a location with warm air, it will start to thaw out.

As your dehumidifier begins to unfreeze you can better assess the situation.

Next, you need to look into why your dehumidifier is freezing up.

Causes of a frozen dehumidifier

There are a few different things that can cause a dehumidifier to freeze up. Below I’ll go over the most common causes of a frozen dehumidifier.

Clogged air filter

One of the most common causes of a frozen dehumidifier is a clogged air filter. Why does a clogged air filter freeze a dehumidifier? One reason: Restricted airflow.

When a dehumidifier’s airflow is restricted, it can’t properly transfer heat between its surroundings.

Dehumidifiers need to get really cold to remove moisture from the air. Specifically, the evaporator coil is the part inside of the dehumidifier that gets cold. If a dehumidifier doesn’t have enough airflow, then its evaporator coil gets too cold and freezes over.

To fix a clogged air filter, you need to remove the air filter and clean it. Most dehumidifiers have reusable filters that can be cleaned out with water. If your filter is excessively dirty, then a little bit of soap will help clean it.

To clean a dehumidifier’s filter, follow these steps:

  1. Turn off the dehumidifier

  2. Open the filter access panel

  3. Remove the air filter

  4. Clean the air filter. Spray the air filter out with water to remove dust build-up. After spraying out the air filter, set it out to dry before replacing it in the dehumidifier.

  5. Reinstall the air filter. After the air filter dries out, install it into the dehumidifier’s filter slot.

  6. Turn on and test the dehumidifier. Plug your dehumidifier in and turn it on. You should have increased airflow with a clean filter. 

Low temperature in room

Another common cause of a frozen dehumidifier using it when the temperature is low. If the temperature is too low, your dehumidifier will freeze up when it runs.

If you need to use a dehumidifier, the room needs to be at least 60°F for the dehumidifier to work properly. If your space is under 60°F, then your dehumidifier will get too cold to work properly. The evaporator coil on the dehumidifier will freeze up when it gets too cold.

Even if your room’s temperature is in the 60s, it’s still not optimal for your dehumidifier. Dehumidifiers work best when the temperature in the room is warm. So you should aim for the temperature of your room to be at least in the 70s for best results.

Broken temperature sensor

Another reason why your dehumidifier is freezing up could be due to a faulty temperature sensor. A broken temperature sensor will make a dehumidifier run constantly—even when it doesn’t need to.

Why does a broken temperature sensor make a dehumidifier freeze up?

First, we need to look at what the temperature sensor is for in the first place.

The temperature sensor on a dehumidifier is used to tell when the coil gets too cold.

Once the dehumidifier’s coil gets too cold, it starts freezing into an ice block.

The temperature sensor lets the dehumidifier know when it needs to turn off and defrost. If the temperature sensor is broken, the dehumidifier doesn’t know when it’s time to turn off. And it ends up running too long and freezing itself.

Most modern dehumidifiers will show you an error code if the temperature sensor is broken. The error code is different for every dehumidifier—so be sure to look at your dehumidifier’s user manual to see what your specific error code is for.

Broken blower motor

A broken blower motor will cause airflow restriction in your dehumidifier. Low airflow ultimately leads to a dehumidifier that ices up.

The purpose of the blower motor is to produce airflow through the dehumidifier. Basically, the blower is the fan that sucks in wet air and blows out dry air.

When the blower motor slows down, the dehumidifier doesn’t get enough airflow through its evaporator coil.

Under normal conditions, the evaporator coil gets cold enough to remove moisture from the air, but not too cold. However, with a broken blower motor, the evaporator coil might not get enough airflow—or none at all. With the reduction in airflow, the evaporator coil gets too cold and freezes up.

There isn’t a quick fix for a broken blower motor. If you suspect that your blower motor is on its way out, the only thing that you can do is replace it. To replace a blower motor, you’ll need to take the dehumidifier apart, remove the existing blower motor, and install a new one.

Replacing a blower motor is a complicated task with a lot of moving parts. So in most cases, it’s better to call an HVAC professional to replace a broken blower motor. 

Dirty or broken blower fan

The blower’s fan wheel is the part that is attached to the fan motor. As the fan wheel spins around, it generates airflow that blows through your dehumidifier.

If your blower fan is dirty or broken, your dehumidifier will suffer from airflow loss and may freeze up.

If you suspect that your blower’s fan wheel is having some trouble, the first thing that you should do is take a look at the fan. Sometimes, the fan can get quite a bit of dust built up on it. If there is an excessive amount of dust stuck to the fan blades, the fan won’t be able to produce enough airflow. 

Broken fan blades can cause airflow loss as well. It’s usually easy to tell if your blower has a broken fan blade. Just listen to the blower when it’s running—if it’s making an excessive amount of noise, that’s a sign that it has some damage.

If your blower’s fan is broken, it needs to be replaced. Replacing the blower fan wheel is a similar process to replacing the blower motor. You’ll need to take the dehumidifier apart, remove the blower fan wheel, and install a new one.

If your blower’s fan wheel is dirty, you’ll need to carefully clean it off. Use a soft-tipped brush or a cloth to remove dust from the fan. Do not use any liquid or chemical cleaners—they may corrode the metal in the fan wheel and reduce its lifespan.

Dirty evaporator coil

A dirty evaporator coil will quickly cause a dehumidifier to freeze up. Why is that?

The evaporator coil is the part of the dehumidifier that gets cold. If the evaporator coil is dirty, then it won’t be able to transfer heat properly. With all that dust and dirt build-up, the evaporator coil gets too cold and freezes over.

How do you fix a dirty evaporator coil? First, you need to check the air filter.

The air filter is responsible for ensuring that dust and debris don’t get sucked into the dehumidifier. If the air filter gets clogged up, then air will get sucked through the tiny cracks around the perimeter of the air filter.

As unfiltered air gets sucked through the tiny cracks and crevices around the air filter, dust will make it past the air filter. Eventually, dust will start building up on the evaporator coil.

To prevent your evaporator coil from getting dirty, clean the air filter at least once a month. You may need to clean your air filter more often if your home is dusty or if you have pets.

Make a habit out of checking your air filter every week—especially if you are running your dehumidifier all day.

Sometimes, you can’t prevent your evaporator coil from getting dirty. The air filter that’s built into your dehumidifier can’t filter out everything. Small microscopic dust particles are able to get by. Fortunately, cleaning your dehumidifier’s evaporator coil is not a very difficult task.

To clean your dehumidifier’s evaporator coil, follow these steps:

  1. Defrost your dehumidifier. You’ll need the dehumidifier to be completely free of ice before cleaning the evaporator coil. To speed up defrosting, run your dehumidifier in fan-only mode.

  2. Unplug your dehumidifier from the power outlet.

  3. Remove the filter access panel from the dehumidifier. The evaporator coil is behind the air filter, so you’ll need to remove the air filter first.

  4. Remove the air filter from the filter slot. Be careful when removing the air filter—if it has dust build-up you don’t want the dust to fall off and get your home dirty.

  5. Clean the evaporator coil. Remove any excess dust build-up from the coil by hand. After that, use a vacuum to suck out the dust from the interior of the coil. If there is any dust or grime build-up inside of the coil, use a coil cleaning solution to clean the coil. Spray the coil cleaner on the evaporator coil and let it soak for 10-20 minutes. After letting the cleaner soak, rinse it off with water.

  6. Put the dehumidifier back together. After the evaporator coil is clean, reassemble the dehumidifier. Put the air filter back in its slot and snap the filter access panel back into place. Turn your dehumidifier back on and see if it works now!

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