Get a FREE Quote Today!
(661) 452-8707

Close this search box.

How to Clean Moldy HVAC Ducts and Equipment

Over time, dust and dirt can collect in HVAC ducts, creating an environment where mold spores can settle and grow. Mold can spread in ductwork and release spores throughout your home. Routine duct cleaning can have many benefits. Making your ducts inhospitable to mold is one of them. But when you suspect a problem, we’ll explain how to clean moldy HVAC ducts and vents.

Mold is a common issue in AC ducts and can cause allergic reactions. Some molds are toxic and can have long-term impacts on your health. Common signs of mold in your AC and/or ducts include:

  • A musty odor that’s strongest near vents
  • Black or green patches on or near vents
  • Airflow from vents is weak
  • Your AC unit has excessive condensation
  • Ductwork looks discolored inside
  • Sneezing, coughing, and other allergy symptoms when the AC is on
  • Headaches, dizziness, or nausea while at home
  • Your energy bills have gone up

How to Remove Mold from Ducts

First, determine if you can remove it yourself. If there are black spots or dust particles around air vents, mold may be growing deep inside the duct system. A wet, slimy material is likely black mold, which is a more serious problem. 

But assuming the issue is manageable, here are some options you can try:

    • Bleach: A mixture of one part bleach with 16 parts water can get air vents clean. First, use a HEPA vacuum on the vents, and then soak a rag with the bleach solution and scrub any moldy spots. Carefully remove the vent cover and soak it for a few minutes. Using a brush, scrub it clean, and wipe down the inside of the vent. Replace the grill once the vent dries.


    • Vinegar: It’s common to see mold on ceilings near moldy HVAC vents. To clean it, pour vinegar into a spray bottle, spray the moldy area, and wait one hour. Soak a clean cloth in plain water and wipe away the mold. If you find hardened fungus and stains, use a scrubbing brush with firm bristles. Then using a dry, absorbent cloth, dab lightly on the areas you cleaned. Open windows to allow for faster drying and to eliminate the vinegar smell.


    • Dish Soap: Mix a few drops of soap with warm water and add it to the vent. After a half hour, vacuum the inside of the vent. Soak a rag with soapy water and wipe the vent grill and duct. Once the grill cover dries, reinstall it over the vent.


  • Detergent: One way to use detergent on moldy HVAC ducts is to soak the grill in water mixed with laundry detergent. Rinse with water after 10 minutes, then remove any remaining dust with a HEPA vacuum. Wipe down the inside again and replace the grill when the area has dried. 


Detergent can also be mixed with baking soda. To create the mixture, use one cup of water, one tablespoon of baking soda, and one tablespoon of laundry detergent. Submerge the grill in the solution for 10 minutes and vacuum the interior of the vent. After soaking a rag in the solution, wipe down the vent and scrub if necessary. Wait until the area is dry before replacing the cover.

  • Bleach and Water: If mold has gotten into the AC, turn off the unit and breaker. Open the unit and inspect the filter; if it has mold, remove and dispose of it. Vacuum out any dust and debris. Then soak a cloth with a mixture of one cup of bleach and a gallon of water. Wipe wherever you see mold. Let the solution sit for 20 minutes, rinse with clean water, and let the AC unit dry before reassembling and turning it back on.

Should I Hire a Professional?

Mold grows in warm, humid places like HVAC ducts. It can also be a sign your AC unit is oversized, preventing it from running long enough to dehumidify the air. Or, if a duct is leaking, warm air may be intruding and creating a mold-friendly environment.

Cleaning mold can be hazardous without the proper tools, knowledge, and protective gear. A professional is equipped to provide a permanent solution. They can also find issues that may be promoting mold growth and correct them to prevent a recurrence.

Monarch Home Services Cleans Moldy HVAC Equipment

Homeowners in the San Joaquin Valley rely on our NATE- and EPA-certified technicians for professional duct cleaning and indoor air quality solutions. Our team always ensures the job is done right. If you suspect mold in the system or wish to schedule regular duct maintenance, call (661) 215-6737 and receive your free quote.

Related Posts