You’ve noticed a difference in your HVAC’s air distribution. Your unit may be blowing less air into your spaces, or you recognize hot and cold spots throughout your home. There are several possible reasons behind these issues, and one of them is HVAC biofilm. Call your AC replacement contractor immediately to have your HVAC system inspected. With their tools and expertise, they’ll be able to tell if biofilm has contaminated the evaporator coil and air ducts.

Biofilm requires immediate and thorough cleaning to improve your HVAC’s energy efficiency and indoor air quality. These dangerous microbes develop in HVAC systems because of their cold, dark, and wet environment.

Keep reading to learn more about biofilm and how you can eliminate and prevent its growth

What Is HVAC Biofilm?
Biofilm grows in HVAC systems because they are often full of moisture and cold enough to act as a breeding ground. It looks like slime and has a slick and slippery texture. This slime sustains all the microbes with the necessary nourishment to grow the colony until maturity. Outside your unit, biofilm can form on many surfaces and environments, particularly in commercial, industrial, and medical facilities.

Unfortunately, biofilm habitats are challenging to spot inside your system. They mostly appear in the HVAC’s most hidden corners. It will require an AC repair specialist to go through the entire system and remove them. That is why routine maintenance and cleaning are important.

Biofilm is harmful not just to your HVAC system but to your family as well. If it grows on your HVAC’s aluminum fins, it means your indoor air quality is no longer good.

A prolonged biofilm infestation also blocks air passage and causes inefficient cooling across your property. It will spread infectious airborne particles and contaminate air-blowing components once it matures.

It’s possible to clean biofilm in your HVAC and entirely remove it. For mild cases, detergents usually work. But for more severe infestation, corrosive cleaning agents will have to be used. Unfortunately, these chemicals can damage your HVAC components, so make sure to discuss your options with your technician.

How Does Biofilm Form?
As we’ve mentioned, biofilm only needs a cold, dark, and wet environment to thrive. Many parts, including your HVAC’s protective casing and chassis, are moist, and dark. A single colony can grow enormously over time and cover your condensate pans, evaporator coils, fans and other components without being detected.

Manufacturers have become aware of biofilm growth and have taken measures to prevent it. One of their preventative solutions includes using antimicrobial coatings on all the components. Unfortunately, biofilm can develop resistance against these coatings over time. Your HVAC is biofilm-free for a certain period, but as your HVAC equipment becomes older, you can expect your technician to spot this problem during AC maintenance and inspection.

How Do I Remove HVAC Biofilm?
If you believe biofilm has infested your HVAC, we recommend calling an expert to help you clean it off safely and remove the microorganisms through tried-and-tested solutions. We urge you not to try opening your unit and cleaning it yourself because you might cause further damage to the components.

Here are some of the ways technicians remove biofilm from HVAC systems:

Thorough Cleaning

HVAC contractors use readily available cleaning products to remove biofilm. They disassemble the unit, inspect the components for biofilm and spray them off with pressurized water and soap. If they detected this issue before the biofilm has established resistance, this simple cleaning method should remove them effectively.

Generally, detergents can be used to get rid of biofilm as long as they are fungistatic or bacteriostatic. HVAC specialists may also recommend other types of detergent that can remove and inhibit the growth of microbes.


Your HVAC specialists may apply EPA-approved antimicrobials to remove the biofilm from your system. It also has the advantage of adding an antimicrobial coating to your HVAC after it is cleaned, improving indoor air quality for a long period. Using these products may not require special equipment.

Some HVAC companies use antimicrobial UV lamps to remove biofilm from the HVAC system. However, these might be impractical DIY maintenance and cleaning because they are expensive tools that might not work as intended on your system.

Unfortunately, antimicrobials won’t work on matured biofilms, which look like hardened gel-like substances requiring manual scrubbing or removal of corrosive substances. Scrubbing and using corrosive cleaning agents can damage several components in your HVAC, so they’re not the most ideal solution.

What Are the Best Ways to Prevent Biofilm Growth?
Prevention is always better than cure. Here are several methods to ensure your HVAC system is safe from biofilm growth and your indoor air quality remains good:

Regular Maintenance

Routine HVAC inspection and cleaning can reduce the chances of biofilm growth. HVAC specialists can check the growth of biofilm and grime in your coils. The biofilm might be at its growth stage in a year, which can still be cleaned using detergents and pressurized water. This ensures they don’t reach their dispersal stage when they start polluting your indoor air. The spores in the dispersal stage go directly into the air you breathe indoors, triggering allergies and possibly causing acute or chronic diseases.

Drain Pan Cleaning

Biofilm can also grow on the drain pan under the coils. The condensation from cooling your property’s rooms heads straight to your drain pan. This makes it an ideal environment for biofilm to grow. Blocked condensation pans will cause damaging spillage and the spread of microbial growth. Your HVAC cleaning company might use antimicrobial pan tablets to prevent biofilm, algae, mold, and grime growth in your condensate pan.

Air Filter Replacement

Filters play a huge role in removing microbes from the air and reducing the chance of biofilm growth in your system. Regularly changing them ensures microbes won’t have a breeding ground and source of nutrition. Washable filters need regular cleaning. They may also require replacement if they become worn and inefficient in filtering contaminants.

If you need top-notch solutions to remove biofilm and prevent it from growing inside your HVAC system, Cool Zone Air Conditioning and Heating can help. To request a service appointment, call us at (623) 253-1018 or fill out this contact form.

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