Dehumidifier Problems: Cleaning and Maintenance Tips

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People who live in moist, humid climates and who are prone to allergies can increase the comfort and health of their homes by using a dehumidifier. 

A dehumidifier removes excess moisture from the air, condensing it into liquid water that is collected in a tank or expelled outside or down a drain, making the surrounding indoor air less humid.

Reduced humidity in the air is helpful and healthful for many reasons. In homes and offices, less humidity in the air means:

  • Less condensation on windows or water pipes, reducing drips that may lead to water damage
  • Less mold and mildew, which are common allergens that thrive in moist environments
  • Less dust and fewer dust mites, which are common allergens, and also a source of dirt and debris that needs to be cleaned
  • Reduction of stale, unpleasant smells and odors in carpets, curtains, and linens

For these reasons and more, many people benefit from having a dehumidifier in their indoor environments, and appreciate the improved air quality.

In order to gain the most benefit from a dehumidifier, it must be properly placed. There are conditions under which a dehumidifier will not work well, so taking these into account when first setting up a dehumidifier will help prevent issues from the beginning:

  • Make sure the dehumidifier is the right size for the space. While a 30-pint unit may be rated for 1,500 square feet of space, if the environment is extremely humid, or there are lots of open doors and windows, a larger unit may be required
  • Consider the temperature of the space. Dehumidifiers won’t operate in temperatures below 60° Fahrenheit, and the coils will freeze. Even low-temperature dehumidifiers won’t work properly in temperatures below 40° Fahrenheit. If a space is damp and also cold, the dehumidifier is not likely to work properly and will require a warmer temperature
  • Place the unit correctly. Dehumidifiers require unrestricted airflow at the intake and exhaust points. It is best to place them with at least 12 inches of unobstructed space around the unit for maximum efficiency
  • Increase the humidistat setting. Although it’s natural to want to set the humidity as low as possible, particularly in the beginning, the dehumidifier will work better for longer (and still keep you comfortable) at settings of 40-50 percent humidity

Even under optimal conditions, like any other appliance, eventually a dehumidifier is bound to have problems. 

Over time, a dehumidifier is likely to stop working as efficiently, or may stop working altogether.

Cleaning and maintenance

Many dehumidifier problems can be prevented with regular cleaning and maintenance. 

Here are some tips on how to maintain your dehumidifier and prevent common problems

As needed

  • Empty the water collection tank and replace it properly within the unit.

Every two weeks (or when the filter light comes on)

  • Remove the air filter and clean it with warm water, mild soap, and a small amount of bleach. Let the filter thoroughly dry before replacing it in the unit
  • Clean the water collection tank with warm water, mild soap, and a small amount of bleach. Mold and mildew can build up in the water tank, and from there, the spores can be dispersed into the surrounding air. Regular cleaning and disinfecting will prevent mold problems. Make sure the water tank is seated correctly when it is replaced in the unit.

Twice a year (or seasonally if needed)

  • Twice a year (or following manufacturer’s instructions), replace the air filter with a new one
  • Clean the air intake and exhaust. Using a vacuum with a soft brush attachment, clean dust and debris from the air intake and exhaust to prevent accumulation and blockage of air flow through the dehumidifier

Regular cleaning and maintenance will prevent many dehumidifier problems and failures, but there are also few common issues that are easy to diagnose and correct on your own.

If the dehumidifier won’t turn on

  • Check the basics. Is the unit plugged in correctly and the power switch on?
  • Empty the water tank. If the water tank is empty, make sure it is properly seated in the unit. If it is empty and correctly seated, feel for the flow switch and make sure that it is able to move freely and correctly; if it’s become blocked or stuck, the unit will think the tank is full when it isn’t, and not turn on

If no air exhausts when the dehumidifier is running

  • It is likely a problem with the fan inside the unit. Use a screwdriver to open the case, and a vacuum cleaner with a soft brush attachment to clean dust and debris inside the dehumidifier. Try to turn the fan by hand and make sure that it turns freely without impacting or rubbing on any internal components

If there is frost on the coils

  • The dehumidifier won’t operate at extremely cold temperatures. If there is frost on the coils, turn the unit off and allow it to defrost. Maintain an adequate temperature in the room, and correct air flow around the unit to keep it operating well. Consider elevating the placement of the dehumidifier; since warm air rises, placing it on a table or shelf may give it access to warmer air in the room

Related: How to Fix Dehumidifier From Iced Up

If it runs but doesn’t reduce the humidity

  • If the dehumidifier is on, but the water tank doesn’t fill or the room remains humid, check the humidistat to set it between 40-50% humidity.
  • If the humidistat is set correctly, but the tank still doesn’t fill, it may be a problem with the refrigeration system. Clean the unit thoroughly and see if that helps the problem.


Most dehumidifier problems can be prevented or diagnosed by thorough cleaning and regular maintenance. 

If you have cleaned the inside of the unit and don’t see any broken parts or problems, it is a good idea to take it to an appliance repair shop for further diagnosis. 

Often the cost of repairs is higher than the cost of replacement, so consult a technician and use your best judgement.

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