Mold in Air Ducts: Causes, Symptoms, Cleaning, Prevention & All That You Need To Know
Summer can be difficult to survive without a properly functioning air conditioning system. Hot and humid environment drains all our energy, preventing us from functioning properly. But thanks to HVAC systems, we’re able to make the most of this wonderful season and get going!
Unfortunately, though, increased humidity during the hot summer months can affect your HVAC unit. A hot and damp environment can lead to the production of mold in air ducts. Therefore, it is necessary that you start taking precautions before you find yourself troubled.
Let’s take a look at what you can do to deal with mold growth!
What Causes Mold to Grow in Air Ducts?
If the environment is favorable for this undesirable fungus, mold can grow and settle in your air ducts. It can even easily spread across your entire home or building through your HVAC system.
The components of an HVAC unit contain moisture from all the dehumidification, which can lead to the production of mold in air ducts. If you don’t maintain the humidity levels inside the ducts, it becomes a source for mold to thrive easily. Since air ducts are closed, dark, and don’t get checked often, it only continues to grow if it’s present. The ducts provide a conducive environment for mold as they collect dust particles, dander, pollen, dead skin cells, etc., which become their source of nourishment.
If you own an oversized AC unit, it can also lead to mold growth. A unit too large for the area won’t run much longer to dehumidify the air. Hence, leaving enough moisture for mold to grow on the metal surface of the ducts. Please read our guide to find the perfect air conditioner size for your room.
In addition to this, any leaks in your roof or the attic area can make your AC ducts wet, providing room for mold growth. Moreover, poor ventilation in the bathroom causes the steam to travel into your rooms and eventually enter the air ducts, creating a perfect environment for mold growth.
Symptoms of Mold in Air Ducts
The only way to verify the presence of mold in air ducts is by sending a sample to a lab for a test or by checking it via a mold testing kit. However, if you’re wondering how to detect mold on your own, then lookout for a few things that are early indicators pointing out the presence of mold in AC ducts. Let’s take a look:
1. Musty Odor
The first thing that can point to the presence of mold in air ducts is a musty odor. It’s difficult to see mold at first as the area inside the vents isn’t very visible; therefore the step to detect mold growth is through bad odor. A mildew-like musty smell when your air conditioner is turned on should alert you at once. Since the air flows through ducts, the bad odor can also spread across all your rooms.
Even though a musty odor won’t always lead to the presence of mold, it narrows down the cause to mold growth.
For more information on air conditioner smells, see our article on why AC smells bad.
2. Black Dust
The presence of black dust around air conditioner vents indicates the presence of mold in ducts. This dust is extremely toxic and is not easy to wipe off. It may also lead to the circulation of mold spores along with conditioned air into your rooms. Immediately contact a professional and turn your HVAC unit off to prevent it from spreading any further.
3. Allergy-Like Symptoms
People who are exposed to mold spores can have adverse health-related issues. If your breathing air is infected with mold, you may suffer from headaches, nasal congestion, itchy eyes, coughing, sneezing, and skin irritation. If you’re facing allergy-like symptoms when you turn your AC on and they go away when off, you should take a look inside your air ducts. The longer you ignore the problem, the worse your symptoms will get.
Learn more about air conditioner allergy and how to prevent it.
4. Visible Mold
You should often take a look around intake vents, ducts, and drip pans because they provide the perfect environment for mold growth. Mold flows through the air in the form of spores that are microscopic particles and you cannot see them with a naked eye. So, when you see any visible signs of mold, it indicates that the infestation is serious and you need to deal with it promptly. It’s best that you contact a professional at this point who can deal with the problem and make sure it doesn’t make its way back.
How to Remove Mold in Air Ducts?
If you suspect mold in your HVAC unit, the EPA suggests not running your AC as it could cause the mold to spread across other parts of your home. It’s best to deal with the problem as early as possible to minimize damage, health hazards, and expense.
Before starting a DIY mold cleaning project, you need to properly dressed. You should be wearing a protective mask with filters since breathing in mold can lead to several health issues. Keep wearing gloves during the cleaning process, and make sure you don’t touch an affected area with bare hands. You should also wear a goggle to prevent mold spores from entering your eyes.
DIY Mold Cleaning Project
To start off with a DIY mold cleaning project, follow the steps below:
- Turn off your HVAC unit and make sure it’s not getting any power from the main switch.
- Next, unscrew the grills on your air vent.
- Use a detergent or a dishwashing liquid and dissolve it into the water to make a cleaning solution. You can also add a spoonful of baking soda. If the surface you’re cleaning is non-porous, you may mix one part bleach with 16 parts water. Soak the vent grills in the solution for 15 minutes.
- Meanwhile, use a HEPA filter vacuum and clean the area inside the air ducts.
- Use the solution and a cloth to clean the surface of the air ducts. You may need a mop to reach the deeper areas inside your ducts.
- Take a scrubbing brush to scrub out any mold, debris, and dirt from your ducts.
- Now, take a clean, dry cloth to dry the area inside the ducts. You must make sure the area is dried out properly and there is no moisture left inside.
- Finally, wipe the air vents grilles clean with water, dry them and reattach using a screwdriver.
- You may also choose to replace the grilles if they have been in use for too long.
- After the cleaning process, discard all cloths and brushes that came in contact with mold.
Looking for more information? Here is a detailed AC ducts guide for cleaning and maintenance.
If the affected area is large and there is a huge amount of visible mold present, you should contact a professional instead of dealing with it yourself. Mold can be dangerous, or at times careful cleaning is required to avoid damage to your HVAC system.
Preventing Mold Growth in AC Ducts
If your HVAC ducts aren’t suffering from mold at the moment or you’re done cleaning and are looking for tactics to prevent it from ever occurring again, here is what you need to do. Add these steps to your regular HVAC maintenance routine, and your air ducts should remain mold-free for a long time!
1. Use Good Quality Air Filters
Air filters play a vital role in keeping harmful particles from getting into your rooms. You should clean them after every two weeks, i.e., 250 hours of use. It is best to replace them after every three months.
Read our AC filter guide to learn more.
2. Clean Drip Pans Regularly
You should take a look at the drip pans of your HVAC unit. Water can collect in the drip pans and become a starting point for mold growth. Clean them and make sure they are dry.
3. Look Out for Leaks To Prevent Molds in Air Ducts
Look out for any leaks around the air ducts and seal them. Any leaks in your attic or roof can also damage your ducts and lead to mold production. Do not delay to fix any leakage problem in your house.
4. Maintain Indoor Humidity Levels
Since moisture is the root cause behind mold production, pay special attention to maintaining the humidity levels inside your home. It is recommended to keep the humidity level below 50% to prevent the growth of mold. You can use a dehumidifier to bring the humidity levels down.
Head to this article and take a look at the ideal indoor humidity chart.
5. Inspect Your Air Ducts Regularly
Since air ducts are closed, you don’t see what’s happening inside. Hence, any development of mold there can go unnoticed. While changing/cleaning air filters, take a quick look inside the air ducts to look for any signs of mold. If you notice any wet area, dry it out without further ado. You can also use EPA registered mold growth inhibitor products while considering your HVAC manufacturer’s guidelines. UV lights or ionization air purifiers can also be installed to kill harmful particles inside the ducts.
We hope the prevention tips mentioned above will help you stay away from the mold growth problem in the future.
Types of Mold in Air Ducts
Mold can be found in different forms and colors. If you’re interested in going to the depths of your mold problem, you may be interested in knows the types of mold that can infest your air ducts. Following are some of the common types of mold found in AC ducts:
It is a type of mold present in white powdery form. Acremonium is mostly found in wet and damp areas around your air vents. It grows over months or even years.
Another commonly found mold strain, Alternaria, has a velvet-like texture. It is usually of green or brown color. This type of mold needs a significant amount of running water through air ducts for its growth.
It is one of the hardest types of mold to deal with because of the various forms that it can take. Aspergillus can appear in many colors, but the most common ones are green, white, or yellow.
Fusarium commonly lives on the surfaces of walls that have been affected by condensation. It can make its way inside air ducts if the water damage to walls also affects the air ducts.
You commonly find this mold in air conditioning units. It spreads to the air ducts and can enter your home with the conditioned air. Mucor is a very toxic type of mold and you need to deal with it immediately.
If you see black mold in air ducts, then it is Stachybotrys. Even though it is easy to spot because of its black color but can go unnoticed as it forms deep inside air ducts. It is very toxic and needs a good amount of moisture to thrive.
Trichoderma lives in air ducts because it needs a constant supply of water to grow. It grows rapidly and it is in the form of spores.
Chaetomium is a brown cotton-like structure. It is difficult to distinguish from other types as it tends to change its color over time.
It is one of the rarest types of mold to be found in air ducts. It is commonly found in kitchen or bathroom corners in the form of black layered substances. Ulocladium is also very difficult to deal with hence requires professional assistance.
Due to the different similarities and many types, mold is difficult to deal with on your own. It is always a good move to talk to a professional before you start to clean your air ducts.