Black Mold on AC Coils: The Dangers and How to Prevent Them

Here's plenty of information on black molds, including how to remove and prevent the issue.
By
Carolina Evans
Carolina Evans
Research Writer
Holds a Master’s degree in Engineering and is keen on her own home’s climate. Sometimes we think that Carolina owns every single product she writes about – that’s ho read more
reviewed
Reviewed By
Richard Powell
Richard Powell
Expert Consultant
For 8 years, Richard had been working as an HVAC specialist and AC unit installer since his student years. Now, he’s our main consultant on every technical aspect that may read more
Last updated: December 27, 2022
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A moldy air conditioner is one of the problems that most homeowners usually experience. Mold likes growing in damp areas which are shielded from direct sunlight. Therefore, it’s not surprising to discover mold in your AC’s evaporator coils.

When mold invades your AC unit, the effects usually go beyond poor performance. The mold can spread throughout your home, causing extensive damage to your property. Additionally, mold can cause respiratory issues. This post highlights factors that cause black mold on AC coils, how to remove it, and prevent the problem. Let’s get cracking!

What Causes Black Mold on AC Coils?

Your air conditioner contains evaporator coils which usually cool and remove moisture from the air that passes through it. The moisture then passes through a drain and flows out of the unit. During the entire process, dust particles from the air also accumulate the in the unit. If your air conditioning unit is dirty, the evaporator coils will not drain off the moisture properly. When the dust particles and the moisture combine, black mold may grow on your coils.

How to Remove Black Mold from the AC Coils

Black Mold on AC Coils: The Dangers and How to Prevent Them

  • Switch off your air conditioner at the thermostat
  • Turn off the power to your indoor unit or furnace
  • Open the duct work’s access panel to expose the evaporator coils, which are usually located in the blower motor housing or furnace
  • Sometimes, the panel could be held in place by screws. Remove the screws with a screwdriver if necessary. One of the best screwdrivers to use is the SKIL Rechargeable 4V Cordless Screwdriver with Circuit Sensor Technology since it’s easy to use.
  • To get rid of the dust covering the coils, use the brush attachment on a shop vacuum. Brush slowly to avoid damaging the delicate fins and coils.
  • Use a soft brush to remove the dirt if you don’t have a vacuum with a hose attachment
  • Spray an alkaline coil cleaner on the coils and fins.
  • Allow the cleaner to set and drip for the time specified by the manufacturer
  • Use a spray bottle filled with water to wash away the cleaner. The drippings will pass through the condensate line
  • Give the fills and coils enough time to dry completely
  • Apply biocide or any other mold-inhibiting substance to kill microorganisms like mold and mildew
  • Replace the duct work’s access panel cover
  • Turn your air conditioner on at the  thermostat Trusted Source How People Actually Use Thermostats Residential thermostats have been a key element in controlling heating and cooling systems for over sixty years. However, today’s modern programmable thermostats (PTs) are complicated and difficult for users to understand, leading to errors in operation and wasted energy. www.osti.gov and test its cooling performance

How to Prevent Black Mold on AC Coils

Preventing mold growth on your AC coils s easier compared to cleaning them. There are various steps you can take to prevent black  mold Trusted Source Mold A microorganism and type of fungus, molds are part of the natural environment and can be found everywhere, outside and indoors. Health-related reactions in people depend on mold type, the amount and duration of exposure, and individual characteristics. www.niehs.nih.gov from growing on your evaporator coils, as discussed below.

Clean the Coils Regularly

Dirty coils usually encourage mold growth. To prevent this problem, clean your coils regularly. For best results, clean the evaporator coils annually.

Cleaning the evaporator coils is not a complicated process. All you need is warm water, mild detergent, and a soft brush. However, you should be extra careful to avoid damaging fragile aluminum fins covering the coils. Ask an  HVAC technician Trusted Source What Does An HVAC Contractor Do? At some point during your time as a homeowner, you’ll need an HVAC (Heating, Ventilation and Air Conditioning) contractor. But what exactly should you expect when you hire one? We’re here to explain. www.forbes.com to help you clean your evaporator coils since they have the proper cleaning tools and knowledge to handle them.

Change the Air Filter Regularly

Your air filter is responsible for trapping dust particles and removing mold spores from the air that passes through the AC, preventing mold from growing on the coils. After some time, excessive dirt may accumulate on the air filter, preventing it from effectively trapping dust or mold spores from the air that passes through the AC unit. As a result, mold may grow on the evaporator coils.

The best way to prevent this issue is by changing the air filter regularly. On average, you should change your AC filter monthly or once in three months, depending on your needs. Also, consider buying a high-quality air filter. The BNX 20x20x1 MERV 13 Air Filter 4 Pack is a good example of a high-quality air filter. This filter can capture microscopic particles and has a single-sided frame technology which helps in reducing environmental waste.

Black Mold on AC Coils: The Dangers and How to Prevent Them

Reduce the Moisture Levels in Your Home

An excessively humid indoor environment can encourage mold growth in your AC. Therefore, it’s important to reduce the humidity levels in your home. The best humidity level for a home is between 30-50 percent.

Use a UV Germicidal Light

Another way to prevent mold growth on your evaporator coils is by installing a UV germicidal light over the evaporator coils. The UV light kills mold spores and reduces their movement, preventing them from spreading throughout the unit. According to most reviews, the best UV Germicidal Light to use is the U/V/C Light Lamp 185nm with 253.7nm Bulb since it has a strong lamp and a long cord.

Final Thoughts

Dealing with black mold on AC coils can be frustrating. The mold can affect your AC’s functionality or even cause respiratory issues. However, you can avoid these issues by preventing mold from growing on the coils. If the mold has already grown on the coils, you can clean them using warm water and mild detergent. For best results, hire a professional HVAC contractor to help you clean the coils.

References

1.
How People Actually Use Thermostats
Residential thermostats have been a key element in controlling heating and cooling systems for over sixty years. However, today’s modern programmable thermostats (PTs) are complicated and difficult for users to understand, leading to errors in operation and wasted energy.
2.
Mold
A microorganism and type of fungus, molds are part of the natural environment and can be found everywhere, outside and indoors. Health-related reactions in people depend on mold type, the amount and duration of exposure, and individual characteristics.
3.
What Does An HVAC Contractor Do?
At some point during your time as a homeowner, you’ll need an HVAC (Heating, Ventilation and Air Conditioning) contractor. But what exactly should you expect when you hire one? We’re here to explain.
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