Dehumidifier freezing up – Steps to fix it and causes

Written by Jason Hutchinson
7 Min read
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Dehumidifiers freezing up are a more common problem than you might expect, in fact, 1 in 5 people who use dehumidifiers say that they have experienced this issue. If you currently have this issue we understand how frustrating this must be, especially if you live in a very humid climate. So in this article, we will explain the potential reasons why your dehumidifier is freezing up and how you can fix it.

And if you have a dehumidifier and it has not frozen up, it may be worth reading on anyway. Because maybe one day your dehumidifier will freeze up and you will be wishing you just took the time out of your day to read this incredibly informative article!

For you to understand why your dehumidifier has stopped working it is probably easier if we first explain how a dehumidifier actually works. That way you will have a better understanding of where the problem is and what you will have to do to fix the problem.

How does my dehumidifier work?

The role of a dehumidifier is to take air from a room and remove the moisture from it, decreasing the relative humidity in the room to anywhere between 30% and 50%. During this process, the air temperature in the room should not be changed as that is not the job of a dehumidifier.

  1. The first thing the dehumidifier needs to do is bring air into it so that it can take the moisture out of it. It does this by sucking in air, creating an airflow.
  2. The first step in the actual dehumidifying process involves the air that has just been sucked into the fan passing over some cold coils. Because the cold coils are significantly cooler than the air in the room, the moisture in the air will condensate on the coils and is removed from the air. For this part, it is important that the air being sucked into the dehumidifier is warm enough (at least 65 degrees Fahrenheit) that it will heat the cold coils up so that they don’t just get cooler and cooler. So the air in the room being too cold could be the root of your problems, as we will explain later.
  3. After the moisture has been removed from the air at the cold coils, the air then needs to be returned to room temperature as it will have been cooled when passing over the cold coils. To heat it back up, it passes over a network of hot coils.
  4. Now that the air has been warmed up it can be blown out of the dehumidifier by a fan and returned to the room drier than before but at the same temperature.

Now that you understand the inner workings of a dehumidifier we can explain what the potential issues are that are causing the dehumidifier to freeze up.

Low room temperature

This is both the most common problem and the easier problem to fix. As we mentioned in our when explaining how dehumidifiers work, the temperature of the air being sucked into the appliance needs to be over 65 degrees Fahrenheit. If the temperature is any lower the cold coils will get too cold, causing the condensation left on the coils to freeze. Ice will build up meaning the coils will stay at too low a temperature.

Now, the main solution to this problem is fairly obvious. You either need to increase the temperature in the room or move the dehumidifier to a warmer part of the room. Maybe your room is over 65 degrees Fahrenheit but the dehumidifier is sat really close to the air conditioning or an open window, meaning it’s is receiving air that is significantly cooler than the rest of the room.

If you can’t get the room that you want to be dehumidified to above 65 degrees you can just put the dehumidifier in another room as it will take the humid air from that room and remove the moisture from it anyway even from another room.

Doing this will prevent the issue from happening again. However, you will probably want to clean the dehumidifier before using it again. To do this unplug the appliance and then remove the frontal plastic panel and the filter behind it. You may need a screwdriver to do this. You will then have access to the cold coil, which you can clean by using a clean rag to wipe off any remaining ice and dust.

Man standing beside a dehumidifier

Broken fan motor

Airflow is vital for a dehumidifier to function because if the warm air stops being sucked in from the outside then there will be nothing to heat the cold coils and ice will start to build up. The same as when the air temperature in the room is not high enough.

The component of the dehumidifier that drives the airflow is the fan and this is powered by the fan motor. If there is a problem with the fan motor the fan will either slow down or stop running entirely. This will cause ice to begin to build up due to the lack of airflow and the ice can even spread to other components lower down on the dehumidifier.

The spread of ice throughout the dehumidifier can cause irreversible damage to the appliance so it is important that if you suspect that there is an issue with the fan motor you check it out and then get it replaced if necessary.

If you do believe that you need a replacement fan motor (or entire fan) it is probably best if you get professional help to replace it as people that specialize in the field will know the type of motor needed for your dehumidifiers fan.

Issues with the humidity and temperature sensors

All dehumidifiers will have components that measure the humidity and temperature of the surrounding area. They do this because they actually have systems in place to prevent the freezing over of the cold coils. If the dehumidifier’s temperature sensor does not work it will not be able to identify when de-icing needs to take place and the cold coils will regularly freeze over with nothing to stop it from happening.

The humidistat or humidity sensor not working can also lead to the dehumidifier freezing over. This is because if the appliance thinks the humidity is much higher than it is it will tell the cold coils to get colder than they need to be. They will reach a temperature at which the air cannot heat them up enough to prevent ice from building up.

Unfortunately, it can be very difficult to identify if the humidistat or temperature sensor is not working, and again, it may be easier for you to do so with the help of a professional. The professional would also be able to assist in replacing the equipment. If you did want to replace them yourselves then you can buy the parts from the majority of hardware stores.

Dirty or old air filters

This problem is similar to the issue with a broken fan, it causes the airflow of the dehumidifier to be far too low leading to it icing over.

The role of the air filter is to protect the rest of the components from all of the harmful particulates and pollutants in the air. If these filters get really dirty and filled with debris they can obstruct the airflow enough that sufficient warm air is not getting to the cold coils and they freeze over.

Now, you should be changing your air filters once a year as a bare minimum but preferably twice. So if your filter is blocked and it is older than 6 months old then it’s not worth trying to clean it, just replace it with a new one. However, if it has been in use for less than 6 months then you can clean it by running it under soapy water and leaving it to dry before vacuuming off any excess debris.

Dirty coils

Hopefully, it should be very obvious to you by now that the coils are very important components of the dehumidifier and if they are not operating at the peak of their powers things start to go wrong. Therefore, if your dehumidifier has frozen over (or overheated for that matter) and you cannot find any other issues with any of the components and the room temperature is 65 degrees or higher, then it could just be that your coils are dirty.

We explained how you can gain access to your coils in the section on room temperature, in this section we also explain how to clean them. Simply use a clean rag to wipe them down, ensuring that any debris, dust, or ice has been removed. Cleaning your coils regularly is good practice anyway as it will ensure that your dehumidifier is always running optimally.

Summing it all up

Hopefully, you now understand that they are two main reasons your dehumidifier may have frozen up. Either the temperature of the air being brought into the appliance is not high enough (65 degrees or over), or the dehumidifier is not receiving enough airflow. There are a number of reasons .why these conditions may not be being met and we have explained these to you in this article so that you can identify a solution.

Therefore, if you read our article through you should have identified the problem and will have your dehumidifier back up and running in no time!

How long should a dehumidifier last?

A good dehumidifier should last you between five and ten years. In order to maximize its lifetime, it is important that you give it the care and attention it needs! This involves regularly cleaning the coils and replacing the air filter every six months.

Should I run my dehumidifier in the winter?

Dehumidifiers should not be run below temperatures of 65 degrees Fahrenheit, if they do they are prone to freezing up. Therefore, if your room temperature is above 65 degrees in winter and you are not happy with the level of humidity inside your house then they are fine to run.

Why is my dehumidifier not collecting water?

If your dehumidifier is not collecting water it means that it is not extracting any moisture from the air. This means that either the air is not humid enough for any moisture to be removed from it or it means your dehumidifier is not operating correctly and is failing to reduce the humidity.

Appliances made simple. 

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