We are all familiar with the routine of changing out our air filters. A clean air filter helps rid our home of dander, dust, and other debris that is circulating the home. It’s not surprising to see a gray layer of fuzz when we change out filters but finding that it has turned black may be a cause for concern. A black air filter could be indicative of an issue in your HVAC system. Triad Mechanical is here to walk you through some troubleshooting steps and help address the problem.

Black Soot Deposition

Black soot can quickly turn our air filters black. This is usually a result of burning candles. Candles are made of carbon-based materials that don’t all combust when burned. They end up producing tiny soot particles which then get into our carpet, on our furniture, and in our air filters.  Scented candles especially are usually a good culprit for black soot deposition because they contain more “impurities” that don’t properly combust.

The best way to fix this is to stop burning candles. But, we understand the love for candles from their good scents to relaxing atmospheres. Instead, you can try the following to keep the soot to a minimum. Try to stick with natural candles made from soy rather than vegetable oil or petroleum jelly. These will burn “cleaner” and allow more of the material to combust. Keep air movement away from the candle flame. Flames that are regularly disturbed will produce more soot so place them in areas away from fans, the AC, or traffic. Finally, get into the habit of trimming your candle wicks before each use. Keep it at ¼ of an inch to minimize soot.


Mold is a very concerning cause of black filters. The black appearance on filters can sometimes be black mold. This occurs when moisture from air conditioning condensation gets transferred to the air filter. Humid conditions and wet environments invite mold. Mold on air filters is a health risk and can exacerbate breathing conditions like COPD or asthma or cause pneumonitis, mold allergies, and other health problems.

With mold, you will want to change out your filters immediately, or have a technician at Triad Mechanical come out as soon as possible to check out your system for you to make sure the mold hasn’t spread.

Clogged Air Filters

If candles or mold aren’t causing your filter worries, then it may just be that it is severely clogged. When this happens, it means you are not changing out your filter regularly so the fix would be to determine a set schedule to check on your filter and swap it for a new one. Clogging restricts airflow causing your system to work harder and affecting the air quality. Implementing a routine for this will solve the problem quickly.

Steps to Take

When you find a black air filter, the first thing you’ll want to do is figure out the cause and get rid of it. Because you’re unsure whether it is candle soot, dust, or mold, you should handle the filter carefully, or call in a professional. Vacuum and clean the area around the filter and try to keep all particles contained. Replace your filter with a new one, and if you haven’t yet, call an HVAC professional in to help diagnose the problem and offer solutions.

Partner with a Professional 

At Triad Mechanical, we are experts in all things HVAC. We offer HVAC Maintenance Programs to our clients in and around Athens, Georgia that include filter maintenance and replacement. Our clients trust us because we stand behind our work. We are committed to making your home comfortable and your HVAC in good shape. Call us now at (770) 682-0075!