Signs of Mold in Air Ducts

South End Plumbing, Heating, & Air Expert Tips

Signs of Mold in Air Ducts

A Musty Odor When Running Heat or AC

When mold exists in the ducts in your home, it will start to emit a distinctive smell. Many people explain the odor of mold as moldy or earthy. The smell of mold may be unpleasant, but the good news is it is a signal you should catch before you’ve got a much larger mold problem on your hands.

When you have mold buildup in your HVAC ducts, the scent will be stronger when the system is running. This is due to the fact the air coming from your ducts will bring more mold spores through the air throughout your home. When your system isn’t running, spores will grow inside the air ducts but the mold is less likely to be noticed.

Illness and Allergic Symptoms

By far one of the most serious effects of having mold in your air ducts and in the air you’re constantly breathing is the health and wellness effects it can trigger for your family. While breathing mold and mildew spores can create symptoms in anyone, some people have a more serious sensitivity to mold. Similarly, mold can exacerbate the symptoms of anybody in your family with pre-existing respiratory problems.

Allergy symptoms such as itchy, watery eyes; coughing and sneezing; and trouble breathing can be signs of mold. If it is present inside your home, mold specifically is a lot more serious in cooler spaces. In even more significant cases, breathing mold  and spores can cause fatigue, nausea, vomiting, diarrhea and cause many health complications for people with already existing health issues. Stop using the HVAC system up until you have had it evaluated for mold if you see these signs in your house.

Noticeable Mold in Air Ducts

Considering that the air from your HVAC system comes in contact with your vents before going into the rooms in your house, it is common to see substantial mold buildup in the vents. Spores will settle on vents and appear as tiny, black or white spots. Even if you do not see mold outside of your vents, you need to remove and inspect them to look for mold growth on the duct-facing side. Cleaning the mold off of vents will make them look better. More important, it will stop illnesses and allergic reactions from mold.

To remove and clean mold off of an air vent register, remove it and immerse it in water, and use laundry cleaning agent and let it soak. This is a great time to vacuum out the open air duct to remove as much mold, dust, pollen and dirt as possible.

Mold Growth in HVAC Units and Parts

The same problems that promote mold growth in your air ducts are additionally present inside your heating system and AC unit. Mold can grow on practically any type of surface as long as it remains in a dark and damp setting. The mold in your ducts may have originated from mold growth in these devices that were spread out through your ductwork as you used your heating and cooling.

The most typical places to see mold development in an air conditioning system are the evaporator coils or the drain pan under them. These parts are frequently covered with condensation that can provide plenty of moisture for mold to grow. You might see mold throughout a furnace as it heats up and humidifies the air inside it.

White Mold in Air Ducts

White mold, or Trichoderma, may likewise have a gray or green color to it. Trichoderma needs a stable supply of water to take root. It grows in spaces where there is excellent air flow, such as a duct. Unfortunately, AC units spread the mold in the air and let expand very quickly in an air duct system.

Black Mold in Air Vents

If you see black dirt settling on your air vents, it may be black mold. Black dirt from mold can be tough to remove, so this is a prospective warning sign that you may have an issue.

An additional sign of black mold is the mildewy odor. Black mold is hazardous, so you must contact a specialist for evaluation if you think your air ducts might have mold. Do not simply try to clean black mold.

According to the EPA, mold expands fast and can be hazardous as it expands. It can additionally be harmful since it can create allergic reactions or breathing issues, so you’ll need to get it evaluated.

Avoid Mold Issues in Air Ducts

To help keep ducts clean and keep mold away from inside ducts, and then your home’s air, use these preventative actions:

  • Replace the filter each month
  • Reduce condensation within the ducts by insulating them
  • Buy a dehumidifier and use it in mildewy or wet areas that might collect mold
  • Clean the drip pans regularly
  • Check for any kind of leaks around the ducts and condensation locations, then seal areas so moisture doesn’t accumulate

Professional Maintenance

If you believe you have black mold or any type of mold in your air ducts, the best step is to contact a professional duct cleaner. Air duct cleaning will make sure there are fewer places for mold and contaminants to continue to exist and grow. Cleaning should not mean you need duct replacements unless there’s been damage.

Duct and HVAC maintenance will be an expense, and it should take a few hours or so to complete in most circumstances. The impact of no upkeep or maintenance, however, will be much more expensive and problematic.

This can additionally be a preventative action to guarantee your vents remain mold-free. Talk with an expert to know what’s best and what your system is due for.


At South End Heating and Air we are Charlotte’s affordable AC experts. Call us anytime for a free consult and free estimate. We’ll evaluate your system and help make recommendations for optimum value. After all, we want to keep you cool all summer long and warm in the winter. Just schedule a visit with one of our technicians to talk about how we can help. Would you like to learn more options our techs can help you with? Give us a call 704-684-5339.

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