How to Fix a Dehumidifier: Everything You Need to Know

Josh Miller

Josh is a contributing writer to the site and former HVAC specialist.

Last Updated on January 19, 2022

Dehumidifiers are electrical appliances that work to reduce and maintain the levels of indoor air humidity. They are usually used for health reasons, sustain comfort, eradicate musty odors, and prevent mold growth by extracting water from the air. As highly versatile systems, you can use them for household, commercial, and even industrial purposes.

Over time, even the best products experience problems. If you notice your dehumidifier isn’t running like it used to and looks like it needs a helping hand, you’ll need to learn how to fix a dehumidifier. After following these instructions, your system will be up and running again in no time.

How Does a Dehumidifier Work?

A dehumidifier is a device filled with components that extract humidity from the air. Consisting of warm condenser coils, cold condenser coils, a fan, and a drain to catch water, these separate units work together and allow the system to do its job.

The fan sends moisture-filled indoor air over the cold coils. Water then condenses and drips into the drain. The drier air passes across the warm coils and is distributed back into the room.

Note that dehumidifiers do not cool the air in your home and are not a replacement for, or alternative to, air conditioning. Dehumidifiers simply make it more comfortable to breathe and live in as they decrease the humidity. However, if the temperature drops below 65°F, they function less efficiently.

For a dehumidifier fan to work, you must provide it with electric power. The evaporator coils require an adequate refrigerant charge, and the controls must work properly for the unit to function. Like a thermostat controls heaters and air conditioners, dehumidifiers work in the same way by cycling off and on via a humidistat that measures the humidity of a room.

How to Repair a Broken Dehumidifier

Use this method if your unit has broken down completely and is showing no signs of life. Start by plugging your humidifier into a working outlet and turn it on to check the power of the unit. Unplug the unit and check there are no damages to the power cord. If this is the root of the problem, you may need to replace the dehumidifier’s power cord.

Next, look for ice by removing the cover panel. If you notice any ice blocking the components, allow it to melt. Do not use the dehumidifier until the room temperature is higher than 65°F. Then remove the overflow cutoff switch and test it. Do this using a volt-ohm meter, clipping the leads to the outlets on the switch.

Re-press the trip level on the cutoff switch. If the needle on the meter shows no signs of both continuity and discontinuity when the switch is pressed back and forth, it is most likely faulty and will need replacing.

Remove the humidistat and check for damages. These components are relatively easy to test using the same volt-ohm meter. You can also find out if your system’s overflow switch works with these meters. Do this by changing the meter to the RX1 scale setting and attaching its leads to the humidistat terminals.

Revolve the knob of the humidistat as far as it will go and turn in both directions. If the volt-ohm meter reveals a zero-ohm reading through a part of the dial range of the humidistat, the device is working. However, if the zero-ohm reading continues through the entire range, it needs replacing.

If your dehumidifier is still showing no signs of life after applying all these steps, you need to decide whether to purchase a replacement or call a repair technician. This decision rests upon your budget and the quality of your dehumidifier, as it may be cheaper to repair an expensive, top-of-the-line unit.

If your repair technician diagnoses the compressor motor or the relay and overload switch as the main issue, they may suggest you order a replacement altogether.

How to Repair an Incompetent Dehumidifier

Use this method if your dehumidifier is still working but not functioning to its optimum capabilities. In this case, the first thing you should do is check your unit’s specifications and ensure it can handle your room size. If you realize your dehumidifier is undersized for the space, but you don’t want to purchase a replacement, you can try closing the doors and dehumidifying sections of the space at a time.

To fix any other components of your unit, start by disconnecting the power cord. After removing the cover of the unit, clean the condenser and evaporator coils. These are the components that collect the highest moisture levels, so it’s always good to regularly give them a spring clean.

Grease the fan motor bearing with a small amount of lightweight household oil – only if your motor has oil parts, as some units don’t require oiling. Ensure the condenser isn’t clogged with dirt and dust. Test your humidistat to ensure it is functioning properly. Do this with the volt-ohm meter, setting it to the RX1 scale, attaching the leads to the humidistat terminals.

If you notice your dehumidifier still isn’t functioning correctly after this maintenance and service, you should call a repair technician. Professional advice can be helpful, and they may also suggest you take your dehumidifier into a repair shop for restoration.

Benefit from a Fully-Functioning Dehumidifier

When it comes to indoor air, you can’t compromise on quality. Dehumidifiers are the ideal systems for removing humidity in the air and making your home more comfortable. There are ways to measure the humidity of your home. If during the summer months you get a bad reading of your home’s humidity, then you’ll need to get a dehumidifier

Whether your unit won’t turn on or it isn’t running as fast as it should be, learning how to fix a dehumidifier is an affordable way to repair the device and continue regulating the humidity level of your home quickly. A home repair job will enable you to get up and running again in no time, but if you get stuck during the repair process, it’s always safer to call in a professional to perform technical work.

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