In a humid climate, little is more frustrating than having your dehumidifier freeze and stop working.
Why does this happen – and what can you do to prevent it?
Excessive humidity can cause damage to your furniture, dampness, promote mold and fungi, and worsen some health conditions and allergies.
What Causes a Dehumidifier to Ice Up?
How to Prevent Your Dehumidifier from Freezing
There are several things that you can do to keep your dehumidifier from freezing up—and to defrost it if it does.
The most common culprits include:
If your dehumidifier coils are freezing while room temperature is higher than 65°, then you may have a problem with the unit’s humidity control unit, also known as a humidistat.
A humidistat is a lot like a thermostat, in that it constantly monitors the level of humidity in the room so the unit can turn itself on and off to maintain a set level in the room. The electrical contacts of a humidistat cause the compressor of your dehumidifier to turn off and on. If the humidistat is not functioning properly, your compressor stays on too long and causes the coils to freeze.
In addition, the electrical contacts in a humidistat can get deformed or covered with a conductive layer of dust, which leads to the same issue.
In order to troubleshoot your humidistat, you’ll want to first disconnect the power to your unit.
Then, turn your humidistat dial and listen for the clicking noise that indicates it is functioning properly.
In addition, you can test for a short in your humidistat using a multi-meter. When you rotate the control, the contacts need to at some point make an open circuit (no current flowing). If they do not, you need to replace the humidistat.
Blower Wheel / Fan Blades
If the humidistat is not the issue, then you may have a problem with your blower wheel/fan blade.
These parts control the flow of air through the unit that is required to prevent the condenser coils from freezing up.
If you’ve cleaned/replaced the air filter, but there is no air flowing through the grill, you should remove the fan cover to inspect the coils.
Take the time to clean off any dirt/debris on the blades that could be preventing air flow.
Then, check the fan blade/blower wheel to make sure that there’s nothing preventing free movement. If wheel or blades appear to be damaged, you’ll want to replace them.
If not, then take the time to carefully clean them.
If neither the humidistat nor the fan are damaged, then the issue may be a faulty or dying fan motor. When a fan motor is damaged, it will often make a high pitched noise indicating mechanical failure and/or a burned electrical smell indicating a short inside the unit.
In both cases, the only fix is to replace the motor entirely – do not attempt to fix it.
I’m a degreed ME (mechanical engineer) who is passionate about machines of all kinds. I created MachineWonders.com as a way to connect with others who love machines like me – or need help choosing one for their needs, application, or situation.