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Can Mold Grow in Your Air Conditioner?

Moldy air vent

At one time or another, you’ve probably experienced that musty, mildewy smell when an air conditioner turns on. It can leave you wondering just how healthy the air is that you’re breathing. Mold is everywhere, even if we can’t see it. So, just how dangerous is it, and what can you do if you suspect mold in your air conditioner? Keep reading to learn all about it and if you have additional questions, don’t hesitate to call WM Buffington of Highspire for all of your heating and cooling needs.  

The Issue With Household Mold

Mold can be found just about anywhere – in your bathroom, in the refrigerator, and sometimes, in your air conditioner. In some cases, mold is something desirable (it’s used to make life-saving medications as well as tasty cheeses!) However, in other cases, mold can cause health issues including nasal stuffiness, throat irritation, coughing or wheezing, eye irritation, or, in some cases, skin irritation.

If mold is growing in your house, it can release spores that can be easily inhaled and people with mold allergies may have more severe reactions. For immune-compromised people and people with chronic lung illnesses, such as obstructive lung disease, mold is an even bigger threat. That’s because when exposed, they can become more prone to a serious infection in their lungs.

Signs of a Mold Infestation  

The dark moist environment of an air conditioner and ventilation ducts can provide the perfect environment for mold to grow. So, how do you know if you have a mold problem in your house? Here are a few signs to watch out for:

  • Noticeable musty smell near air vents 
  • Increased musty smell when AC is running
  • Black “dust” around air vents
  • Visible mold patches around vents, evaporator coils, or near drip pans.

What Causes Mold in an Air Conditioner or Near Vents?

Mold needs two things in order to grow: moisture and an organic food source. Moisture can come from high humidity or a leak or spill that is not cleaned up properly. Condenser and evaporator coils are the main contributors to condensation, and therefore have potential for water leakage if not properly drained. 

The food source can be the surface the mold is growing on, like wood or carpet, or organic particles found in dust, if there is enough of it. Under most circumstances, air conditioners and HVAC ducts are not hospitable places for mold to grow. Sheet metal ducts and styrofoam channels inside window units do not offer mold as a food source. However, dust often collects in these places, which can allow mold to grow.

Mold growing in an AC unit is not necessarily more dangerous than mold growing elsewhere in your house, the concern is that it could become more widespread throughout your home. Since the purpose of your HVAC ducts is to distribute air throughout the house, if they become contaminated with mold, they will efficiently distribute mold spores across an entire room or the entire house. If the concentration of mold spores is high enough, you will have a mold problem everywhere, rather than in just one location, and you will be inhaling mold spores in every room, even while you sleep. 

How to Get Rid of Mold in Your AC 

If you have confirmed that you have mold growing in your AC system, you’ll want to take the necessary steps to eliminate as much as you can, as soon as possible. The process of cleaning mold out of an air conditioner is dependent on the type of unit. If you have a smaller window unit or portable system, you can try to tackle this project on your own. If you have a central air conditioning system, however, it’s best to call in the professionals. 

General Process of Removing Mold

Before beginning the process, you’ll want to make sure that you’re in a well-ventilated area (open the windows!) and have the necessary protective equipment. You should wear non-porous gloves and a face mask with goggles – especially if you are sensitive to mold.

Armed with a household cleaner and a cloth or sponge, you’ll want to manually remove any visible mold. Keep in mind that mold may be located inside the unit or behind the grill so take care when trying to access these parts and always make sure your unit is unplugged first. If mold has grown on a porous surface such as wood, plaster, carpet or upholstery, you will probably not be able to get rid of all the mold. The moldy item or section will need to be removed, thrown away, and replaced. 

You’ll also want to address the filter in your AC unit. For filters that are not disposable, remove any visible mold and debris and submerge the filter in a mix of 10 parts water to 1 part bleach. Allow it to soak for 10 minutes, then rinse and air dry. In case of significant mold growth, replacing a unit would cost much less than removing the mold from it. This is especially true for smaller and less expensive free-standing or window units.

Mold Removal By Unit Type 

Window units

By the time you see small mold spots forming on the air direction vanes or grate of your window air conditioner, it is probably too late. The mold you see is just the tip of the iceberg. You can disassemble the unit and try to clean mold from the internal air ducts, coils, evaporators, and other parts, but there is always a chance you will miss some and the mold will simply grow back. A moldy window unit likely needs to be replaced.

Central AC

Mold growing in the ductwork of your central AC system will almost certainly require professional remediation. The EPA suggests you shut off the system as soon as you notice mold to prevent it from spreading. The ducts will need to be vacuumed and cleaned, which could become very expensive and difficult if it has spread throughout the entire system. Sheet metal ducts are much easier to clean than fiberglass, plastic, or lined ducts. The EPA does not recommend applying biocides or surface treatments to kill or prevent mold in ductwork.

Portable AC Units

Clean the drain line and then remove the lid of the portable AC unit and inspect the coils. Clean it thoroughly with a damp cloth soaked in a mild bleach solution to ensure that nothing is sticking to it and then replace the air filter. 

Tips to Prevent Future Mold Problems 

Controlling moisture is the key to preventing mold in air conditioners. Unfortunately, air conditioners can also be a source of moisture. Here are a few tips that you can follow to keep your air clean and mold-free!

  • Window units should fit the window tightly to prevent rain and humid outdoor air from entering the room.
  • Window units should be tilted slightly toward the outside to allow this condensation to drain properly.
  • Grates and filters in window units should be cleaned regularly to prevent dust build-up, which can provide a food source for mold and impede airflow.
  • Whole house AC units should have a drainage system
  • If you have a drainage system, make sure it’s working properly so moisture does not collect around the unit or get introduced into the ducts
  • HVAC ducts tend to self-regulate moisture because the airflow dries them out. Keep all grates and air returns unblocked and clean to allow air to flow properly to all parts of the system.
  • Replace air filters regularly. Clogged filters not only provide a food source for mold, but they can impede airflow.
  • Use a dehumidifier to rid your home of excess humidity, especially if you live in an area with high moisture levels.
  • Never introduce moisture to your HVAC system. Duct cleaning should use dry vacuuming or dry wiping, never water.
  • Portable AC units need to be emptied periodically. Make sure they are emptied and dry before storing them for the winter. 
  • Keep up with regular maintenance. HVAC professionals can catch issues early and help mitigate any problems.

Need Professional Help? Call WM Buffington!

If you are concerned about mold growth in your air conditioner or need help getting rid of it, call an experienced HVAC company that can help. WM Buffington has been serving Southeast Pennsylvania residents for over seven decades! Give us a call and let us know how we can help you.

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