Why Is The Dehumidifier Freezing Up?

What a pain in the keester.

The temperature is soaring.  The humidity is through the roof.
Now the Dehumidifier is icing over.

How does this even make sense?


 The middle of Summer. 100 Degrees and the AC and dehumidifier keep freezing over.

What gives?

Why is the dehumidifier freezing up?


1. The room temperature is too low.
2. Blockage. The air flow is interrupted.
3. Malfunctioning humidistat.
4. Fan is not working

Dehumidifiers and air conditioners work on the exact same principle.
If you have an air conditioner that is freezing up, then you can figure out, using the same logic, why your dehumidifier is freezing up.

Air conditioners and dehumidifiers both pull warm air over refrigerated coils that cause humidity in the air to turn to condensate.

In the case of an air conditioner it’s to exchange the warm air for cool air in the room.

In the case of a dehumidifier it is to reduce the moisture content of the air in the room.

1. The Room Temperature is too Low


Usually the most obvious reason a dehumidifier is freezing up is that the temperature in the room in which its operating is too low.

Dehumidifiers are meant to run at temperatures 65 degrees and over.

Imagine if the air that is being pulled over the refrigerated coils is hot, then the result is going to be condensation like on the outside of a glass of water sitting in the sun.

But if the air that is being pulled across the refrigeration is not hot, then the liquid in the air is not going to turn to condensation, it is going to turn to ice.

That doesn’t mean that the whole machine is going to be a block of ice, it just means that there may be areas in your coil system that are icy or even in some cases completely iced over.

The fix is easy. Turn the machine off and let it thaw out. Then make sure you’re not running your dehumidifier in cool air unless you bought a dehumidifier that is specifically made for winner air.


humidifier freezing

2. Blockage

Another thing that can cause your dehumidifier to freeze up is a blockage that is not allowing your air to flow freely across the refrigeration coils.

In other words you have something either clogging up your filter or you have the unit too close to the wall where the air cannot enter and exit easily. In some instances you may have debris actually get inside the machine and and prohibit the air from flowing through it.

It’s the same concept as running the dehumidifier into low of a temperature.

If the air that is over the refrigeration coils is not allowed to flow freely it will eventually freeze.

The fix for this is easy also. Clean the filter. Make sure the placement of the machine is not in an area where air cannot Flow in and out freely. And open it up to make sure that there is no trash or debris inside that could cause the air to be slowed.

Even though most problems with dehumidifiers and air conditioners freezing can be solved very easily using the methods we stated above, there are also going to be times when the problem is mechanical.

If you have a dehumidifier that it is freezing up and you have ensured that you’re not using it in a room that is too cold or that you have a blockage that is prohibiting the air from flowing through the machine easily,

3. Humidistat Malfunction

There is always a chance that your humidistat is not working.

The humidistat on a dehumidifier is basically the thermostat that tells the machine when to turn on and turn off based on the temperature in the room.

If the temperature in the room drops too much and the humidistat does not communicate with the machine to tell it to turn off then the machine will continue running when the air in the room is too cold and the refrigeration coils will freeze over.

The fix for this is not going to be as easy.
If you’re mechanically inclined, then you may be able to take a tester and test out the humidistat easily enough. And the part itself is held on by a couple of screws usually.

But if you’re not mechanically inclined then you’ll probably want to hire a technician to do the job for you.

4. Broken Fan

Another mechanical problem that can happen that would cause your dehumidifier to freeze over is the malfunctioning of the fan.

Related to the airflow being prohibited when you have a blockage is the function of the fan moving air through the machine evenly and often.

If the fan is not working then the air will not flow through the machine as designed and can end up lingering over the freezing refrigerated coils too long and cause your unit to freeze over.

The fix for replacing a fan or fan motor is the most difficult thing to fix when your dehumidifier is freezing over.

It is recommended that you call a technician to check and replace the fan motor if needed.

Depending on the price that you paid for the dehumidifier and the price of the part and the cost of the service, you might be looking at the cost of a new dehumidifier as well.


Why does the dehumidifier keep freezing up

Why does the dehumidifier keep freezing up?

There’s only a few things that can go wrong when a dehumidifier is freezing up.

A couple are very easy to deal with and a couple not so much.

Typically if the dehumidifier is freezing up it’s because the temperature in the room is too cold and instead of the air that is passing over the freezing refrigerated coils turning to condensation, it turns to ice.

And easy enough fix. Turn it off and let it thaw. Then make sure you don’t run it in a cool room below 65 degrees.

Similar to the first problem is airflow. If your filter is too clogged or if you have something in the way of the machine causing the air not to flow freely then the air cannot move easily across the refrigerator coils and the humidity inside of the air will freeze instead of turning to condensation.

Another easy fix. Remove the blockage, clean the filter, make sure the placement of the machine is not inhibited by a wall or any other thing.

The humidistat is a mechanical problem that if it goes out or is not working properly will keep your dehumidifier from turning off at the right time, allowing your dehumidifier to keep going when the air is too cold. Which causes freezing.

Replace the humidistat. Fairly easy job that even a novice technician can accomplish easily.

Lastly and related to the issues with air flow is the fan itself. If the fan has gone out, then they are going inside of the machine will not be forced out evenly and can eventually freeze.

This is the most difficult fix. It is also one that you’ll probably want to call a service man or get someone that is mechanically inclined to deal with.
Parts and labor might be comparable to buying a new machine at this point.


Published by

Dennis Reed

Dennis Reed Owner and Author @ BreatheBetterAir.org