How to Fix a Humidifier | HomeTips
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How to Fix a Humidifier

Like all appliances, sometimes humidifiers do not function properly and require simple troubleshooting and repairs.Typical problems are that they don’t work at all or that they work but fail to humidify a room properly.

Always check your manufacturer’s instructions first, and understand that some repairs you perform yourself may void your warranty.

repair humidifier multimeter

Multimeter       Photo: Innova

Tabletop and console humidifiers are controlled by a humidistat that turns the unit off and on when the humidity levels stray from a set range. If you don’t believe your humidifier is maintaining the proper humidity for your room or house, check its humidistat.

Though a humidistat allows for more or less “automatic” operation, you will need to dial it up and down as the temperature changes in order to maintain fairly constant indoor relative humidity levels.

Keep in mind that higher humidity levels in cold air will make the air feel colder. If you have a humidifier and your house feels cold in the winter, even when your heating system is working correctly, then your humidistat may be set improperly or may be working incorrectly.

You can test a humidistat with a volt-ohm meter.

To establish whether power is reaching the humidistat when you know there are no problems with the plug or switches, unplug the humidifier, remove the control panel, and lift the lid. Test the humidistat with a multimeter or volt-ohm meter set to the RX1 scale (or to K-Ω or Ω resistance on a digital meter). Clip the meter to the humidistat terminals. The meter should jump if you turn the humidistat from high to low. If it doesn’t, you’ll need to replace the humidistat or return the humidifier to the manufacturer.

Humidifier Does Not Work

When a humidifier doesn’t run, it generally means it isn’t receiving electrical power or the controls have automatically shut it off. Do the following to source the problem:

1Be sure the humidifier is plugged into an outlet that works and that the unit is turned on. Check the electrical receptacle for power using a working lamp, appliance, or voltage tester. If the receptacle seems to be dead, check the circuit breaker or fuse that serves the humidifier’s circuit.

2Check the setting on the humidistat. If it’s set lower than the room’s relative humidity, the humidifier won’t go on; in fact, it may take several hours for the humidistat to respond to the room’s changing humidity.

3Be sure the humidifier’s reservoir is full of water.


4Unplug the humidifier unit. Check the power cord and, if need be, repair or replace it.


5Remove the humidifier’s cover panel. Remove the humidistat and check it as described above. Replace it if necessary.

6If the humidifier still doesn’t work, call an appliance repair person, take the unit into an appliance repair shop, or replace the unit.

Humidifier Works But Not Well

If your humidifier doesn’t do a good job or runs constantly, it may be undersized for the space or humidified air may be escaping from the room. Perform these diagnostics:

1Check the unit’s specifications to be sure it can handle the room size.


2Be sure your home’s doors and windows are closed; also check the fireplace damper.

3Be sure the reservoir has plenty of water.


4Be sure walls or curtains are not blocking the unit.


5Disconnect the power cord and clean the unit according to the owner’s manual.


6Lubricate the fan motor bearings with a couple of drops of light oil if the motor has oil holes (some units are oil-less).

7If the humidifier still operates poorly, call an appliance repair person or take the unit into an appliance repair shop.

Humidifier Makes Noise, Leaks or Smells Bad

Though humidifiers can work reliably for several years, they can take on certain problems with time—most of these are issues that have to do with wear and tear or maintenance. Here’s a look at how to diagnose and treat some of the more common issues.

Working Parts of a Humidifier  ©

Working Parts of a Humidifier ©

Humidifier Makes Noise

A noisy humidifier may be the result of a fan motor or a drive mechanism that is not lubricated or is clogged with debris. Periodically clean the water reservoir, fan, and nozzle to ensure they are working properly.

Lubricate the fan motor bearings with SAE #20 oil. Be sure to consult your owner’s manual for other proper care and maintenance procedures to keep your humidifier functioning smoothly and efficiently.

Another cause of noise can be vibrating parts. To check for this:

1Unplug the unit, remove the cover, and look for any loose parts. Tighten any loose screws.

2Wiggle the fan to see if it is loose on its shaft. If it is, tighten the mounting fasteners.

3If the humidifier continues to makes noise, call an appliance repair person or take the unit into an appliance repair shop.

Humidifier Leaks

If water drips or pools at the base of your humidifier:

1Disconnect the power. Check the pan or reservoir, and empty it if necessary.


2Be sure the wick, hose, or other water-delivery system isn’t kinked or fouled.


3Be sure there are no cracks or broken seals in the water reservoir.

Humidifier Smells Bad

Odors are common because water stagnates in the tank. Over time, this grows mildew, mold, and bacteria that can stink. Cleaning a humidifier usually eliminates odors.

Don’t use chemical household cleaners or bleach to clean a humidifier—they can leave a residue and be caustic to parts. Instead, use vinegar (its odor will dissipate quickly) and hydrogen peroxide to clean the reservoir and filter. Use these two non-toxic cleansers in sequence, first applying and removing the vinegar, and then repeating with the hydrogen peroxide (this helps remove the vinegar’s smell). Work with two spray bottles—one filled with full-strength white vinegar and the other filled with full-strength hydrogen peroxide.

1 Unplug the unit, empty the reservoir, and mop up any damp areas.


2Clean the reservoir. Spray the inside with vinegar, allow to sit for 10 minutes, thoroughly rinse with clear water, and wipe with a clean rag or new sponge. Repeat the same process with the hydrogen peroxide.

3Clean the evaporator belt or pads. If you have manufacturer’s recommendations for cleaning the inside of the humidifier, follow them. If you can’t find directions, remove the cover to access the evaporator belt or pads, spray these surfaces with vinegar, and brush with a soft brush. Allow this to sit for 10 minutes, and then rinse thoroughly. Then repeat with hydrogen peroxide, let it sit for 10 minutes, rinse again, and wipe clean with a clean rag.

4Wipe or vacuum the fan blades clean. If the fan has a cover, remove it. Then use a damp cloth or vacuum to clean the fan blades and the area around the motor.


About Don Vandervort
Author Image
Don Vandervort developed his expertise more than 30 years ago as Building Editor for both Sunset Books and Home Magazine. He has written more than 30 home improvement books and countless magazine articles. He appeared regularly on HGTV’s “The Fix,” and served as MSN’s home expert. Don founded HomeTips in 1996.

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  1. I have 2 full house humidifiers that have stopped functioning right. There are new filters, fan runs, tanks are full of water but they are not empting into the base. They have worked for part of the winter and now nothing seems to help…I loosened the caps thinking I had them too tight….. nothing seems to work .I have had humidifiers for 20 years and this is the first time this has happened to me. The humidifiers are only 2 years old. Any suggestions??

  2. i washed my humidifier i may have gotten the inside wet will it ever work again?


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