How To Clean Mildew From AC Vents: Easy 4-Step DIY Guide

As molds, mildew, and spores can everywhere by hitching a ride on the air moving around your estate, you need to know how to clean mildew from AC vents — and we’ll present it in four steps. They can surely reach anywhere air goes, and those vents are set up so well, you won’t even notice there’s a lot of them already.

AC vents may be hidden, but they are vital to a particular structure’s complete functionality. As they are the ducts that serve as roads for fresh air from the outdoors to reach your rooms, they also require periodic attention, that is, if you want to breathe high-quality air.

how to clean mildew from ac vents

High-rise buildings and massive towers usually employ a team to put that attention on schedule, which most of the time is their only concern for their paycheck. Small-scale businesses, leasing users, and practical homeowners shoulder this job alone, especially the need to check such AC vents in a specific time frame. 


Steps For Cleaning Mildew In AC Vents

Aircon vents relay air from the outside to you, so they can carry even undesirable minute things to get suspended. Fungi and their spores fall under such a category, so they can infiltrate your vents, and if the filter in those ducts is in poor shape, mildew can start amassing.

Regular cleaning for HVAC vents is typically scheduled on an interval of years(about 3-5 years). For irregular and emergency cases of smelly rooms, especially musty ones typical with mildew infestations, we have some steps to remove them.


Step #1. Prepare equipment and cleaning tools

Preparation should be your first step in cleaning something as unusual as AC vents, which would mean collecting everything you need. You need a vacuum(preferably HEPA) capable of sucking and filtering the spores and mildew, a mildew-killing solution, detergent, sponge, and rags for drying.

After taking all these items near the vents you’re cleaning, you need to effectively prepare a cleaning solution that would work against the mildew. While there are many commercial products available for mildew, a bleach solution will suffice for home or office levels of use.

Mix the bleach with water to have a 10% solution (10 mL of bleach for every liter of water). Make sure to pour the bleach into the measured water and not the other way around.


Step #2. Turn off the AC and vacuum through the vents

After adequately mixing the solution, make sure you turn off your air conditioner and unplug it from the socket since electrocution and short circuits are possible later on when you work with water. Let the AC be for at least 15 minutes before you start cleaning.

Pick up your vacuum and work it through all the mildew and mold you see in the unit. You can unscrew a few bolts if you’re familiar with how your unit works and vacuum inside too.

Note the parts you remove for returning later and put the vacuum away after use.


Step #3. Wipe the vents with bleach solution

The vacuum should now have reduced the mildew mass in your vents. The next part is wiping off the vent’s surface with a mildew-killing solution.

Soak your sponge with the solution you prepared earlier and wipe the inner and outer surfaces of the vents. Remember to limit the water exposure of your AC, especially if this is your first time doing it, to avoid causing any damage.

Always squeeze excess liquid out of the sponge before and after wiping.


Step #4. Wipe with soap and dry

Mix the detergent with water and use it to wipe the surfaces of the vents again. This will help reduce the stench of the bleach from the unit and avoid any disturbing smell in your room later on.

After which, dry the whole AC with rags you’ve prepared early on. You can run the AC with another round of vacuum to ensure no dirt and fungi are left in it.

If you’re aiming to get a new AC unit, here’s an article on how much does it cost to run a 10000 BTU air conditioner.


What causes mildew in AC vents?

Mildew growth on any surface can usually be trickled down into availability of all its survival criteria, which is commonly presented by ACs and therefore, their vents. Vents are dark spaces that can collect organics for the spore to thrive through, and if such spores get carried there, moisture is all that’s necessary for occupancy.

Unfortunately, these ACs get moisture to help condition the air, which can also go to the ducts, supporting mildew growth. Condensation also happens in these vents that help prolong the stay of the mildew.

To fully combat this, read this article on what causes condensation on air conditioner vents.


Do cleaning services clean mildew in AC vents?

Cleaning services specializing in aircon and AC vent clean-up typically cover mildew cases on their full sweep. Some of them would appreciate you calling them ahead and informing them of the mildew presence earlier to prepare a professional cleaning solution to assure the fungi doesn’t return.

Cleaning services are typically tasked with a full sweep for areas you couldn’t reach. This is why they can name fees worth all the years you can spend without worrying about fungi.



It’s not simple to learn how to clean mildew from AC vents since there can be danger regarding the electricity. Despite that, successfully doing it yourself is something to brag about.

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