skip to Main Content

Steps to Prevent Mold Problems in Your HVAC System and Air Ducts

Mold Problems in HVAC System and Air Ducts

Unfortunately, mold is all around us. It’s in the air we breathe and resting on all our home surfaces. Add a bit of moisture, and you’ve got fuzzy green or black spots staring you down. Plenty of areas around your home are bastions for mold growth. Your HVAC system, unfortunately, is one of those perfect spawning grounds for stubborn molds.

If you want to learn more about combating mold in your HVAC system, we’ve got the strategies you need. Read on for more information.

Are you still struggling with mold issues and looking for quality Sterling HVAC repair? Cardinal Plumbing, Cooling and Heating has the HVAC experts you need to tackle even the most stubborn HVAC problems. Give us a call at 703-645-4528.

What Causes Mold Problems in HVAC Systems?

Mold spores are prevalent in the air. If you were able to shrink down to the microscopic level, you’d see the atmosphere filled with spores of all kinds. To the naked eye, spores are invisible. If they happen to land on a nice moist spot in your home, then the real growth starts.

Mold can be dangerous, so you need to take its growth seriously. Some molds can cause nasty health side effects. Other molds may not be noticeable. 

People who are sensitive to molds, have asthma or other respiratory issues are the most likely to experience adverse health effects. If you or someone in your home fits this description, it’s imperative to keep a watchful eye on your HVAC system for any signs of mold growth.

When it comes to air conditioners, mold tends to be a fairly common problem. Dealing with and preventing mold is a part of proper air quality control. Understanding what causes mold growth and how to handle it when it pops up is essential to keeping your home’s air clean.

You should be aware of a few problem areas when mold issues start to bother your HVAC system. 


Mold needs moisture. If you can control moisture in your home, you’ve got a good shot at keeping mold at bay.

Handling humidity is easier said than done, especially if you live in a particularly humid environment. When the summer months come, and the rain starts to fall, dealing with the mugginess from the outside is almost impossible.
Humidity is going to get into your home. If you don’t do anything about it, humidity can be the catalyst for mold growth inside your home and HVAC system.

Indoor showers, baths and saunas are common producers of humidity, so keep that in mind.


Thermodynamics is tricky, but condensation is common. While some of us might not understand how it happens, we can all be victims of the results of condensation in your ducts and your main unit.

The cooling process that your HVAC system goes through each day produces condensation. Normally, this excess moisture is moved away from the system through the condensate pan. However, clogs or other issues can prevent proper draining.

Clogged condensate lines create standing water. Standing water creates mold. 

Poor Ventilation

If moisture is the issue, then proper ventilation is the solution. Ensuring that your home is adequately ventilated and that moisture has somewhere to move is integral to battling mold.

Without ventilation, stagnant air pockets can form in your home. Moisture that has nowhere to go is the perfect scenario for mold growth. Bathroom fans and range hood exhaust systems are some common problem areas where ventilation is an issue.

Signs of Mold in HVAC Systems

Since mold spores are virtually invisible to the naked eye, how can you spot mold growth in your HVAC system? Severe mold infestations are usually easy to spot. In cases where mold has been left unattended, you can spot speckles on air registers and vents.

Another tell-tale sign that mold is living rent-free in your home is the odor. If you are experiencing a particularly funky smell, it could mean you’ve got some new moldy neighbors — think wet dog with a touch of old cheese.

HVAC specialists are no strangers to mold, and they will know what’s what when it comes to your system’s mold issues. So if you are on the lookout for mold, Sterling HVAC specialists Cardinal Plumbing, Cooling and Heating are here to help.

How to Prevent Mold Problems

If you are sufficiently afraid of mold at this point, you may be wondering: “how can I prevent mold?” Good question. Humans have been dealing with mold as long as we’ve been living indoors — even further back if you count cheesemaking and other moldy endeavors.

The one thing we have gleaned from years of battling stubborn molds is that if you control moisture, you control mold. Therefore, moisture control should be your strategy to prevent nasty mold infestations.

Here are some tips to help you prevent mold growth in your HVAC system:

  • Replace your HVAC filters regularly
  • Insulate air ducts to help reduce condensation
  • Check and clean your condensate/drip pans
  • If you find leaks, handle them promptly to prevent moisture build-up

The above steps are the low-hanging fruit of mold control. They cost next to nothing and can have some significant effects. If you are in a humid environment, or mold issues are common in your home, you can enlist a little extra help.

The first thing you might want to try is a dehumidifier. Placing dehumidifiers in key areas in your home can help pull moisture from your ducts and other HVAC components.

Another tactic you should employ is to hire heating and AC repair specialists. Cardinal Plumbing, Cooling and Heating offers duct cleaning services that can help stop mold growth before a serious infestation occurs.

Steps to Remove Mold from Heating and AC System

If you are looking at the moldy spots near your vents with frustration, here is how you can channel that rage toward tackling that nasty infestation.

First, remember that mold can be dangerous. You need to don the proper PPE when handling mold problems.

This means:

  • An N95 mask
  • Industrial grade gloves
  • Safety goggles

You may even want to invest in a painter’s suit that you can dispose of after finishing. Next come the tools of the trade. Keep in mind: whatever you use to clean mold, you will need to throw it away. If you don’t, you could be inviting mold right back into your home.

You will want a soft brush and some rags to do the dirty work. You can use a few cleaning solutions to tackle mold. The first is a home remedy.


  • One tablespoon household detergent (dish soap or detergent)
  • Half tablespoon baking soda
  • One cup water

If you are dealing with severe mold growth, consider using an EPA-approved mold detergent.

Now, onto the actual cleaning process:

  1. Turn off your HVAC system and make sure all the heating/cooling vents are not pushing air.
  2. Start by spraying moldy areas with cleaner and scrubbing gently with a brush or rag.
  3. Repeat until you’ve reached all the spots where visible mold is present.
  4. Dispose of all rags and PPE in trash bags and immediately take them outside.

The last step is important. All your hard work goes right down the drain if you let the spores come right back. Proper disposal ensures that the mold is far away from your home.

Finding Affordable Heating and AC Repair in Sterling, VA

Mold can be a challenge even for experienced professionals. To have the best chance at living in a mold-free home, you need to get all the help you can.
If you are searching for the best Sterling HVAC repair, look no further than the team at Cardinal Plumbing, Cooling and Heating. Reach out online to schedule an appointment.

Share this article

Back To Top