Published: February 15, 2018


One of the most common complaints we receive is about mold build-up in HVAC systems. Mold can be extremely dangerous, especially if it isn’t caught early. It can lead to eye irritations, skin reactions, respiratory illness or worse. Spaces with high moisture levels are most susceptible to mold growth, leading air conditioning units to be common culprits.

The first step in dealing with mold is identifying you have a problem. Here are some signs to look for:

  1. Funky smells: mold has an unpleasant musty smell. You may notice this smell worsens when you turn on the A/C.
  2. Visible signs: look for black, patchy residue that may not wipe off easily.
  3. Respiratory issues: if you or someone in your family begins experiencing respiratory issues for no apparent reason, it’s a big warning sign you may have mold build-up somewhere in your home.

If you do find mold and it isn’t excessive, you may attempt to remove it yourself. Follow these steps:

  1. Always wear a mask to prevent the mold and the chemicals from the cleaning solution from entering into your lungs. The EPA suggests wearing an N95 mask, rubber gloves and protective eyewear.
  2. Turn off your HVAC system. You must turn off your unit to access the parts you need to clean. This also prevents the chemicals from cleaning solutions from flowing throughout your home.
  3. Clean the infested areas with mold and mildew removal products thoroughly. Ask a professional for recommendations on products to use or make your own. If you’re making your own, consider these solutions:
    • Mix household detergent with water.
    • Mix 1 tablespoon of detergent with ½ cup of baking soda and 1 cup of water.
    • Mix 1 part borax with 16 parts water.
    • Mix 1 part bleach with 16 parts water.
  4. Scrub and vacuum the affected areas. Use a generous amount of cleaning solution and use a brush, wet rag or spray bottle. Let the solution sit for a few minutes before scrubbing the area in a circular motion. Then get rid of excess solution and finish up by vacuuming the area. You may need to repeat this process if you haven’t gotten rid of the entire mold build-up after one cleaning.
  5. After you’ve eliminated all the mold, dispose of the rags or towels you used by double bagging them and throwing them away outside. If your vacuum has a filter, please take proper precautions regarding disposal or cleaning.

Preventing mold build-up in the future

Once the affected area is completely clean, consider installing filters made to reduce mold growth. Ultraviolet lights work well to sanitize high-risk areas and commercial inhibitors can control mold growth in your HVAC system. Monitor the moldy area to see if it comes back over the next few days and weeks. If you do have a recurring mold issue, it may indicate a larger moisture problem and will require an HVAC professional.

Remember, mold is preventable by maintaining your HVAC system and getting regular HVAC checks on a yearly basis. If you are unsure if you have mold or if you’re experiencing a persistent mold problem, give us a call. We’re happy to take a look and make the proper recommendations.