How To Clean Black Mold From Air Conditioner Vents And Ducts

Here is how to clean a moldy air conditioner.

Mold spores can travel almost anywhere and settle in areas that are conducive enough.

This is why you can find them on your basement walls, shower tiles, sink drains, and even in your HVAC ducts.

This AC mold removal guide provides all you need to clean and prevent infestation of your HVAC systems.

Air Duct Mold Removal Guide

In this article, we’ll be discussing how to remove mold from your air conditioner ducts, as well as the causes and signs.

Keep reading!

What Causes Mold In Ductwork?

When an area is warm and filled with moisture, mold spores can easily settle there.

Your air conditioning system can produce water vapor inside the duct system when cold air moves through. And when the water vapor levels are high in the outer environment, the droplets gather up instead of evaporating.

When this happens, a perfect environment is created for mold spores to settle and grow.

As for nutrition, mold can get that off all the dirt, dead skin cells, animal dander, and pollen that has built up over time inside the duct with the aid of water.

Is Air Conditioning Mold A Problem?

Mold has been proven to be a serious health hazard. Even the World Health Organization (WHO) has acknowledged this fact.

The spores can complicate respiratory issues, cause allergies, headaches, and other forms of irritation. As if that isn’t enough, it also has a musty smell.

Having mold in a room is quite different from having it in your HVAC system.

Mold in AC units is a big problem. This is because the vents spread the spores to as many rooms that are connected to the system.

This can be catastrophic if you have your family living with you, as the mold can spread and contaminate as many areas and people around your home.

The musty smell can also be spread through the HVAC system and leave several rooms smelling terrible.

How Do I Know If I Have Mold In My HVAC System?

Mold lodged in your HVAC system may not be visible, but there are other ways to tell if they are growing in there.

Their musty odor is one of the major pointers to mold growth in your air conditioning system. If you notice this awful odor in several adjacent rooms, then you most likely have mold in your HVAC system.

For more severe Infestations, you can spot the mold growing around the ducts and vents.

Black Mold in AC Unit Symptoms

Other signs of mold growth in your AC ducts include the following –

  • Irritated eyes, throat, and nose when AC is turned on, or when you walk into an air-conditioned room
  • Allergic reactions when in an air-conditioned room (rashes, watery eyes, and runny nose)
  • Unexplainable headaches that stop once you step outside
  • Nausea
  • Fatigue
  • Dizziness
  • Visual confirmation (seeing the mold grow around your drip pans or air ducts)

If you live in an area where the climate is warm, and your home is constantly smelling musty, then you should suspect that mold is growing in your AC ducts.

Upon suspicion, begin to take steps to eradicate mold from your ducts before the matter worsens.

How To Remove Mold In HVAC System

Do you know how to get rid of mold in air ducts of ACs and other HVAC units?

You can tackle the mold infestation in your HVAC system if it is minor. However, you would need to call a professional service if the infestation is in more complicated sections of the system.

The EPA advises that you call an expert if the mold has covered a span of 10 square feet and above.

If after careful inspection you find that the infestation is not severe, then you can use several common household products to remove them.

Follow these steps to remove mold in the air conditioner unit.

Step one: Protect yourself from air vent mold

We have already mentioned how much of a hazard mold can be, but that’s not the only reason you need to protect yourself during cleaning. The cleaning solution you are using is also toxic, so you need to guard yourself against it as well.

You need a pair of rubber gloves to protect your hands from touching the mold and cleaning solution. You will also need protective glasses to keep the flying mold spores from hitting your eyes and mouth.

Last but definitely not least, you should put on a facemask to block off the musty smell, as well mold particles from your nose and mouth.

Step two: Make your cleaning solution or buy a commercial cleaner

For those who are not interested in making a solution themselves, you can simply buy an EPA-approved commercial mold cleaner.

But if you don’t mind the DIY approach, you can make a solution all by yourself.

  • Air Conditioner Mold Spray

Baking soda is a great product for HVAC mold removal. A bleach solution can also do the trick.

To make your solution, take a tablespoon of household detergent and mix with half a tablespoon of baking soda into a cup of water.

Alternatively, you can mix one part bleach with 16 parts water to treat non-porous surfaces.

This recipe is often used for mold in air ducts treatment.

Step three: Turn off the AC system

Place the cleaning solution in a safe space, one where pets or children cannot reach. When your solution is safely put away, turn off the HVAC system.

Cleaning with the system still turned on could be hazardous!

Step 4: Mold removal from air ducts by scrubbing

Grab the bucket containing the duct mold cleaner as well as a brush. Dip the brush in the solution then begin scrubbing the affected areas of the duct.

Dip your hands in as far as it can reach to get as much mold as you can.

The dip and scrub should be repeated several times until you can no longer see the mold.

Step five: Wipe the ducts with a dry cloth

Grab a dry cloth and wipe away the leftover moisture in the ducts. Ensure your hands go as deep as possible into the ducts to get more mold out.

After the first wipe, you can get another dry cloth and wipe the area again to remove any remaining mold particles.

Run the wipe one more time if need be.

Step six: Throw the rags away

Once you are done cleaning the mold, dispose of the rags safely. Place them in an air-tight trash bag and throw them in the outdoor bin.

Don’t make the mistake of dropping the rags on the floor after cleaning. This will deposit some of the spores on the ground, and that’s a problem.

The spores may be dead, but research has shown that dead mold is just as dangerous as living mold.

Make sure you have the air-tight trash bags beside you as you wipe the ducts with the rag. This will make disposal faster.

That’s it, you’re done!

you’ve successfully cleaned off the visible mold from your AC ducts.

Remember to call a professional mold cleaning service for mold infestation around inaccessible areas of the duct.

How To Prevent Mold In Air Conditioner Unit

Cleaning mold is one thing, preventing them from growing back is another.

Don’t forget that the HVAC system is perfect for mold growth, so they can grow back in a matter of weeks if preventive measures are not taken.

One of the best ways to keep them from coming back is to use an EPA registered mold growth inhibitor immediately after cleaning.

Mold infestations are persistent, which means you need to act fast before they grow again and cause you untold expenses.

Luckily, there are many steps you can take to prevent mold from growing back into your HVAC system.

We will list them out below.

  • Replace the HVAC system filters
  • Insulate the air ducts to reduce the condensation levels inside the ducts
  • Practice regular cleaning of the drip pans (when the drip pan collects water, it becomes a perfect breeding environment for mold)
  • Seal condensation and leaks (although the EPA doesn’t recommend using sealants unless there is no other option)

You can also buy a dehumidifier from a home improvement store (that’s if you don’t already have one). The humidity level should not go beyond 60%, as this is the ideal range for mold growth.

Place the dehumidifier close to the areas close to mold growth for better results.

When the aerial water vapor content is low, the water will evaporate faster from the ducts, thereby reducing the chances of mold growth.

Another thing you can do to prevent future mold growth in your ducts is to inspect them regularly. If you don’t know what to look for during inspection, then call on the professionals to do it for you.

As we have mentioned before, mold can be very persistent, and it can grow back if proper care is not taken.


Mold in your HVAC system is more problematic than mold in any other part of the house. This is because the HVAC system can spread it to all the rooms connected to it and cause health problems to those that are exposed.

Most experts advise that you call a professional mold cleaning service to handle mold in AC systems. But you can handle it yourself if the infestation isn’t severe.

Take care!

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