How can I Remove the Mold in my Home’s HVAC System?

An HVAC system having mold in it is a common complaint. Mold is a cunning little pest. It can significantly worsen indoor air quality, grow and spread, and make building inhabitants ill without ever being observed (IAQ). And a forced-air HVAC system is the fastest way to spread mold throughout a building.

Visible mold on your basement walls, carpet, or drywall is a problem. However, the presence of mold in HVAC (heating, ventilation, and air conditioning) systems poses a serious risk to you, your family, and even your pets. When your furnace or air conditioner runs, the fan turns on, and the airflow disperses mold spores throughout your entire home if your HVAC system has mold. Every room will be contaminated with mold spores.

When there is moisture inside the ductwork in your home, mold can grow there. On hot days, the humidity in the air can condense in the ductwork when your air conditioner circulates cool air through it. On the ducts’ walls, the moisture in the air condenses into beads. This dampness makes it possible for mold spores to spread and establish a colony inside the ducting.

What Causes The HVAC Air Ducts to Get Infested with Mold?

Mold growth inside the ducts is especially prone to occur in warm, humid environments. When cold air moves through the duct system, water vapour can occur, and when the outside air has a high water vapour concentration, the water droplets typically gather rather than evaporate. It creates the conditions that mold may thrive in the best. Typically, the dust, dirt, dead skin cells, pollen, and animal dander that accumulates over months inside the duct with the water serves as the mold’s food source.

An further frequent cause is incorrect AC system sizing. Your system can be too big or too little, which allows for inefficient system performance and could cause condensation problems.

Condensed moisture accumulating in the condensation line or drain pan of the HVAC system results in yet another issue. Sometimes a small obstruction will make this trapped moisture a problem.

Why Are My Air Vents Covered in Mold?

If you’ve seen mold growing on your air vents, you might be wondering why. This is due to a number of various factors.


Mold loves to thrive in moist areas, and air vents are regrettably quite humid places (4).

⇒ Humidity

You should anticipate to find mold in your air vents because humidity is a major factor in the growth of mold. This may be found on the air vents of equipment such dryers, stoves, refrigerators, and central heating and air conditioning units.

⇒ Warmth

Mold prospers in warm conditions as well. This is particularly true in situations where heated air meets cooler surfaces, like the air vent itself. Condensation is a result of this, and it can

How to Remove Mold

Here are some suggestions you may provide your HVAC contractor for cleaning it up if you routinely inspect your system but you still receive complaints about it (mold starts to spread in as little as 48 hours):


  • Deactivate your HVAC system.
  • Wearing at least an N-95 respirator is required for all participants in this cleaning.
  • Any porous materials that have been wet, like filters or insulation, should be changed. Use plastic bags that are at least 6 mil thick to double bag the trash.
  • Rent a fogger for mold removal.

A hardware store will have a mold fogger available for rent or purchase. Mold spores have been found to be killed by high doses of the chemical used to control mold. For even surface application, the fogger atomizes a mold control solution into a thin mist.

  • Apply the mold preventative.

Apply the mold inhibitor to each component of your HVAC system as directed by the manufacturer after cleaning the ducting. This will lessen the spread of any new mold.


In the end, a mold infestation in your ductwork and HVAC system is a major health issue. Mold eradication is a big project for do-it-yourselfers and is frequently ineffective. The issue won’t go away if you have an unidentified leak in your ductwork or a problem with your HVAC components that is causing moisture to build up and cause mold to grow.

Consult a knowledgeable HVAC contractor before attempting to diagnose or fix the problem. These specialists are skilled in removing mold and working with ductwork. They can examine your system, identify the origin and severity of any mold infestation, and then quickly and securely remove all of the mold from it.

News Reporter