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Air Conditioning Checking

Why Is My Home’s Air Filter Turning Black?

Updated: Feb 10, 2023

We all (hopefully) know we should be changing the air filter in our HVAC system about once each month. Your air filter works to trap dander, dirt, dust and the like from dispersing throughout your home, so it’s only natural to see dust buildup. But while some dust accumulation on the air filter is normal, if you find your air filter is black, it could be indicative of another issue with your heating and cooling system.

No matter which way you slice it, when you change your air filter, it shouldn’t be black. There are two main culprits that can cause your air filter to take a much darker appearance (hello there, soot and mold) and neither are good! Fortunately, figuring out what is causing your air filters to be black is the first step in addressing the problem. Here’s how to start.

Black and White Air Filter

3 Reasons Your Air Filter is Black

Black dust in your air filter could be caused a number of things, such as:

1. Black Soot

Soot can quickly turn your air filters black, leaving you surprised when you remove to filter to replace it with a clean one. Soot is typically caused one of two ways: candles or gas water heaters.

Black soot is a byproduct of burning candles. For the most part, burning candles is harmless, but the buildup of excess candle soot can make your air filter less efficient overall. While the best option is to stop burning candles, you don’t have to give up your love of candles just yet.

– You can prevent candle soot from turning your AC filters black by trimming candle wicks to one-quarter inch before lighting the candle each time

– Opt for all-natural candles made from soy and avoid using candles made from petroleum jelly or vegetable oil

– Avoid excess airflow around the candle to help reduce soot production

Gas water heaters can also produce black soot. If you have a gas water heater make sure the color of the flame is blue, which indicates a clean burn. If the flame is flickering, there may be an issue.

2. Mold

While black soot is not a welcome sight on your air filter, mold is worse. When you run your air conditioning system, condensation collects on the evaporator coil (especially in humid conditions like the good ol’ Sunshine State). This moisture can transfer to the air filter where black mold can begin to grow.

If you find mold growing on the air filter, it’s important to dispose of the air filter immediately and replace your AC’s air filter. Besides worsening allergy symptoms, mold can cause asthma, fungal sinusitis, pneumonitis and more, so it’s important to take care of the issue right away. Find the source of the mold and call a technician to inspect your HVAC system to ensure that mold isn’t growing within the air handler.

3. Your Air Filter is Severely Clogged

If neither soot nor mold is causing your air filter to be black, it is likely severely clogged. When your air filter is clogged, it can restrict airflow, hindering your home’s indoor air quality while damaging your HVAC system in the process. A clogged air filter won’t be able to effectively stop pollutants, such as pet dander, from infiltrating your home, which can lessen the air quality you and your family breathes. Also, because air can’t pass easily through the filter, your system will run for longer periods of time, putting unnecessary wear and tear on your system.

What to Do After Finding a Black Air Filter

1. Remove the dirty filter and immediately dispose of it 2. Vacuum around the area where the filter sits and make sure you don’t see black particles or debris in the air 3. Replace your filter with a fresh, clean filter 4. Call a professional HVAC expert to inspect your HVAC system

AC Maintenance Services In Orlando

Your air filter is one of the most important components of your air conditioning system. After all, the air filter is what helps keep the air in your home clean for you and your family to breathe. If you’ve noticed your air filters are black, give the professionals at Energy Air a call. Your family’s safety is our top priority, so our trained technicians will determine what is causing the discoloration and how to fix it. Contact us today to learn more or conveniently schedule an appointment online.

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1 Comment

Jul 30, 2023

It is due to the reason that your HVAC unit has not been cleaned on regular basis which turns the filter to trap dust and dirt on it for a long time.. This results in turning filter black. It is important to get it cleaned regularly by contacting an HVAC contractor to keep it clean so that you will have a clean and fresh air.


Contact Energy Air

Whether you need a single air conditioning unit installed or a complete air conditioning system retrofit, our team of HVAC experts will handle it. Have questions or would like to discuss your project? Give us a call today to talk to one of our friendly team members, or schedule your appointment online.

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