How to Remove Mold From Air Conditioner Ducts

  • Cleaning mold in air ducts isn’t only a matter of visual appearance. The health problems symptoms that we experience while being in the apartment may be a sign of mold in your air and may further worsen the health of inhabitants. It’s the reason why you must remove mold as fast as possible. 
  • There are several ways to get rid of the mold and mildew in air vents. You can reach out to professionals or use your DIY baking soda or bleach solution.  This article will focus on mold removal to take our health back on the right track. 
  • Getting rid of mold in air ducts is necessary, but it’s even more important to pay attention to prevention. Mold loves to come back, so be sure you do everything to detect signs and kill mold before it could appear.

The invisible enemy in the HVAC system air ducts

The most challenging part of removing mold from the HVAC system, heating, and air conditioner ducts is that we can’t see it! 

It’s never easy to combat an invisible enemy. 

Everything looks good until it isn’t anymore. Then, we start to feel down; the air we breathe loses quality; something is wrong. 

How to recognize mold in your air conditioner? 

For starters, let’s see how to recognize that there is mold in air ducts?

There are signs that you’ve got mold growth within home HVAC systems:

Mildew-like or musty smell 

You notice a strong, disturbing smell throughout the house. 

Other words to describe it would be: musty, damp, wet, stale, or rotten.

Does anything ring a bell?

Well, it’s probably mold that decided to take over your place.  

Also, the odor is more prominent when your heating or air conditioning is turned on.

Important: We appreciate the power that your nose has in smelling dangers, but don’t go up to the air vents sniffing all over the place. You could expose yourself to unpleasant health symptoms. Instead, you better use your hand to waft the air towards you and sniff that way.

Nose, throat, and eyes irritation 

Your body sensors are upset when you switch on the air conditioning or step inside an air-conditioned room. 

The HVAC system that calls for duct cleaning likely causes these respiratory effects in humans:

  • coughing, 
  • wheezing, 
  • asthma-like symptoms, 
  • shortness of breath, 
  • hypersensitivity pneumonitis, 
  • infections, 
  • sinusitis.
  • hay fever, etc.

Allergic symptoms

Things like runny nose, rashes, and watering eyes should make you pay attention to your in-house air ducts.


A sure sign that something is wrong inside your possession is when it stops happening after going outside. 

Unexpectedly appearing headaches are one of the signs of mold at your place. 

Nausea, fatigue, and dizziness 

Yet, these symptoms exclusively appear when you’re inside your apartment. If you go to your MD, everything disappears. Weird, isn’t it? 

Instead of checking with yourself, you better see if your vents and ducts need professional help. 


Mold infestation is one sure sign that it’s cohabiting our place, whether we want it or not.

If you can see the mold growth with your bare eyes, well, it is there indeed. 

Look for it:

  • within ​the intake vents
  • around the air ducts and drip pans

Why is there mold in my HVAC system air ducts?

It’s all related to several natural effects of the ductwork functioning. 

Not to focus too much on physics, let us say that it all boils down to five factors:

  1. Moisture
  2. Warmth
  3. Poor ventilation
  4. Oversized AC unit
  5. Your AC is too cold

The ultimate air ducts cleaning solution 

There are plenty of ways for mold removal and air ducts cleaning. 

Some mold removal detergents are available for purchase, so you don’t have to make it yourself from scratch.  

With the suitable detergent (whether it’s a ready one or DIY), you can get to work; but be careful! 

It’s all about thoroughly conducting the process while protecting your health doing it. 

Keep in mind that it’s always better to prevent mold from appearing than to deal with it afterward.

Professional mold removal services are there to help, so don’t force yourself into this ductwork enterprise if you don’t feel like it. 

The DIY solutions are most suitable for minor mold problems and isolated cases that don’t involve the entire ductwork. 

Mold removing solutions

There are a few homemade ways to deal with mold spores in HVAC systems. 

Baking soda and detergent

To create this solution for mold removal, you’ll need: 

1. one tablespoon of household detergent

2. half tablespoon baking soda

3. one cup water

So, let’s get our hands-on experience. 

How to get rid of mold in air ducts?

Equip yourself with:

  • a mask, 
  • thick industrial grade gloves, 
  • coveralls, and 
  • safety goggles. 

It’s not only mold but also chemicals protection.

1. Turn off the heating/cooling vents.

2. Reach the spot where you can see the mold growth.

3. Scrub the moldy areas thoroughly. Use a wet rag or a light brush.

4. Repeat if the mold infestation is robust.

5. Dispose of the rags in airtight trash bags (use six mil or thicker trash bags).


Another home remedy that you can use is saturated bleach. 

1. Mix together one part bleach in 16 parts water. It will do the trick on non-porous substances. Keep a little of the solution aside for later.

2. Turn off your air conditioning or heating.

3. Vacuum the air vents.

3. Dip a rag into your bleach solution and scrub the air vents.

4. Unscrew the air vents and dip them into the bleach solution.

5. While they are soaking, use your reserved bleach solution to clean the inside of the air vents. Then, use a clean rag to dampen it with the solution and clean the inside.

6. Let the ductwork dry thoroughly.

7. After about 15 minutes of your air vent soaking, use a scrubbing brush or rag to scrub it clean.

8. Let the air vent dry thoroughly before reattaching.

Important: How to make sure that mold spores never come back to your HVAC ducts? Look for EPA registered mold growth inhibitors. They are made to prevent mold from growing again after mold remediation. Without applying it, you can be sure that the fungus comes back within a few weeks.


There are several ways to take care of the HVAC system so the black mold doesn’t show up and the air remains clean. 

How to keep the mold spores away?

Regular check-up 

To keep your heating and air conditioning HVAC from signs of mold grows, check the ducts regularly. 

If you notice there may be issues (spores related or not), look for a way to get rid of them or call for professionals.

Remember that molds are persistent beasts. They are likely to come back to a conducive spot even after rigorous cleanup regimes.

Replace the HVAC system filters

To prevent your HVAC machinery, take care of filters by changing them regularly before mold can even show up.  

Get rid of moisture 

It’s crucial to keep the moisture away if we want to avoid black mold in air vents. 

The thing is that HVAC systems work in a way where water is involved. That’s why it’s so susceptible to mold in vents and ducts, and in consequence, mold in your air.

How to control the moisture in air vents?

1. Reduce condensation within the ducts by insulating the air ducts.

2. Clean the drip pans regularly. Water in the drip pan nurtures mold colonies.

3. Seal condensation and leaks to keep the entire duct system dry. 

Tip: Be careful while approving the use of sealants. The EPA recommends the use of sealants only if other alternatives are unviable.

4. Buy a good dehumidifier and switch it on near the moldy areas. The low water vapor content in the air will help faster evaporation of water from the ductwork. This, in turn, will prevent the further growth of mold.

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Frequently Asked Questions

If the mold issue isn't overwhelming, you can search for DIY solutions online and try them out. However, if the black mold infestation starts to take over the place, don't hesitate and call for professionals to make your vents clean again. The EPA recommends the employment of professional mold removing services when mold cover spreads over ten sq ft.
Mold problems in HVAC systems and air ducts occur for two main reasons: humidity and water accumulation. Remember that seeing a small amount of mold doesn't mean that the problem is minor. Molds spread through spores, and a small colony will lead to an infestation in no time.
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