How to Dehumidify a Car

If you left your car windows open during a rainstorm or forgot to take out your bathing suit after going to the pool, your car may need to be dehumidified. If your car is soaked, dry it out. You may be even able to prevent musty smells and mildew from forming! If you’ve already got a mold problem, clean out the mildew and take care of any lingering dampness. Then make sure you prevent mildew from invading your car ever again by checking for leaks and removing sources of dampness right away.

Method 1

Method 1 of 3:

Drying out Your Wet Car

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1
Vacuum up lots of water with a wet/dry vac. If your car is soaked or if there’s a lot of standing water, you’ll want to start by getting that out. Use a wet/dry vac to remove the excess water. Take off the top of the vacuum and remove the dry filter. Then plug in the vacuum and start sucking up the water!^{[1]XExpert SourceVictor Belavus
Air Conditioning SpecialistExpert Interview. 6 May 2020.}
- If you don’t have a wet/dry vac, you can rent one from a hardware retailer or an appliance rentals center.
Take out all the carpets and put them in the sun to dry. Using the wet/dry vac, vacuum up any water that was hanging out under the mats. Leave the mats out overnight. Run the vacuum over them if they’re still damp in the morning.^{[2]XResearch source}
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Put several thick towels on the upholstery. This should absorb most of the water. Check back in a few hours to switch out damp towels and replace them with new ones. Remove the towels before you go to bed.^{[3]XResearch source}
If you can, leave all the doors open for at least 8-12 hours. Aim several large standing fans at the interior of the car. Focus especially on the seats. Let the fans run on their highest setting for at least 8 hours, or preferably overnight.^{[4]XExpert SourceVictor Belavus
Air Conditioning SpecialistExpert Interview. 6 May 2020.}
5
Use baking soda to absorb the remaining moisture. If you managed to dry your car out quickly, you shouldn’t get any mold growth or musty smells. Just in case, sprinkle some baking soda all over the seats and mats. Leave this on for 24 hours, and then vacuum it up with the wet/dry vac.^{[5]XResearch source}
- Baking soda can be used on all types of car interiors, including leather.

Method 2

Method 2 of 3:

Cleaning Mildew out of Your Car

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If you can, take advantage of the sun and outdoor air. This will help dry out any dampness that’s causing mildew to form in your car. You’ll also want to dry out your mats in the sun.^{[6]XResearch source}
Since you’re dealing with mold, it’s a good idea to protect yourself. Wear a mask and latex gloves. After you’ve finished cleaning the car, thoroughly wash your hands and change your clothing.^{[7]XResearch source}
3
Remove mats and check for dampness. Mildew often grows in storage areas or on the floors of your car. Check the spare tire compartment, then look under all the mats. Don’t forget the trunk. You should also see if your air conditioner is leaking by feeling for damp spots on the mat that sits underneath the filter.^{[8]XResearch source}
- Leave the mats out and put them in the sun to dry.
4
Scrub off mold with a nylon brush. Once you’ve found your mold spots, tackle them with a nylon brush.^{[9]XResearch source} You don’t need to use any soap or water, as this could actually make the mold problem worse.^{[10]XResearch source} Just scrub at the mold until it’s removed from all the surfaces in your car. Then vacuum up all the broken-down mold particles.
- If the mold has left stains, use a carpet and upholstery stain remover. Follow the instructions on the bottle.
- If you’re cleaning leather, you may want to use a soft-bristled brush to avoid scratching it.
5
Spray the seats with white distilled vinegar. Fill a spray bottle with white distilled vinegar. Spray it on the seats and any affected mats or carpeting. This will kill the mold. Leave it on there to soak in for about 10 minutes.^{[11]XExpert SourceVictor Belavus
Air Conditioning SpecialistExpert Interview. 6 May 2020.}
- Vinegar can be used on leather and cloth interiors. If you’re concerned that it’ll damage your car, however, spot-test a small area of the interior by putting a little vinegar on it and letting it sit for 10 minutes.
Go over the entire interior with the wet/dry vac. Vacuum up the vinegar and any remaining dampness. Pay special attention to the areas where you found mold.^{[12]XResearch source}
Go to your local hardware store to find an anti-mold powder. Sprinkle it on the seats, carpeting, floors, and mats. This will kill off any remaining spores. Let it sit for about five minutes, then vacuum it up.^{[13]XResearch source}
The baking soda will absorb the rest of the moisture. Allow it to sit on the surfaces of the car for about 12 hours or overnight. Then use the wet/dry vac to vacuum it up. Replace the mats and enjoy your mildew-free car!^{[14]XResearch source}

Method 3

Method 3 of 3:

Preventing Mildew and Mold Growth

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Fill a small container with baking soda. Put it on one of the floors of your car to continuously absorb moisture. Check the container every few days and replace the baking soda when it gets damp.^{[15]XResearch source}
Ask a buddy to sit inside your car while you spray it with a hose. They can see if any water leaks through windows, doors, sun and moon roofs, or even the floors. If you’ve got leaks, go to a repair shop to plug them up as soon as possible.^{[16]XResearch source}
Leaving wet clothes, towels, or even a cup of water in your car could cause the air inside the car to become damp. This might lead to the growth of mold and the return of that dreaded musty smell! To keep your car dehumidified, remove sources of dampness when you leave the car.^{[17]XResearch source}
If your car does get damp on the inside, dry it out quickly. Vacuum the carpets and leave the windows and doors open overnight. Sprinkle some baking soda. Addressing moisture quickly will keep you from having to do a deeper clean.^{[18]XResearch source}
5
Clean your car every two weeks. Remove all trash. Wipe down the hard surfaces of the interior. Vacuum the mats and seats. Use upholstery cleaner to address any stains or dirt on the seats, then re-vacuum them.^{[19]XResearch source}
- If your seats are leather, use saddle soap to clean them.

Expert Q&A

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Can you use a dehumidifier in a car?
Victor Belavus
Air Conditioning Specialist
Victor Belavus is an Air Conditioning Specialist and the Owner of 212 HVAC, an air condition repair and installation company based in Brooklyn, New York. In addition to HVAC and air conditioning units, Victor also specializes in furnace repair and air duct cleaning. He has over 10 years of experience working with HVAC systems.
Victor Belavus
Air Conditioning Specialist
Expert Answer
There's no good reason you can't. Just park near an outlet, plug the dehumidifier in, and leave it running in the car. You probably won't be able to do this all the time, but it may be an easy way to suck some moisture out of your vehicle after the interior got wet.
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Wet/dry vacs can be used on all types of car interiors. If you’re worried about scratching leather interiors, just put less pressure on the vacuum attachment when you’re vacuuming the leather.
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