Does Your Air Conditioner Smell Musty? Here’s How To Solve It
An air conditioner that smells musty could be caused by dirty air filters, mold, or mildew. Should you handle the issue yourself or call a professional?
A musty smell coming from your air conditioner needs to be resolved quickly. Our guide will explain common reasons why a bad smell is emitting from your air conditioning system, how to troubleshoot and fix the issue, and when to get professional help.
Why Does My Air Conditioner Smell Musty?
It’s not normal for an air conditioner to emit a foul smell. When issues are present, an air conditioning system might give off a musty smell reminiscent of dirty laundry, mold, or even spoiled hardboiled eggs. Musty smells from air conditioner units are often caused by water accumulation in drip lines, ducts, and drain pans.
There are other reasons why your air conditioner might smell musty. HVAC units are breeding grounds for mold. Mold can grow in most air conditioning systems, including window units, central air conditioners, and freestanding, portable units. There are thousands of types of molds and fungus. A few common kinds homeowners might find in their AC unit include Aspergillus, often associated with allergies, Cladosporium, and Stachybotrys chartarum, or black mold.
Stachybotrys chartarum is a hazardous mold that produces poisonous mycotoxins that can cause respiratory problems and allergic reactions. Act quickly if you notice a musty smell in your HVAC unit. Mold or mildew growth can affect the indoor air quality in your home and may lead to long-term health implications.
Causes of Musty Smell in Air Conditioners
There are a variety of reasons why you might notice a musty odor from your cooling system. Here are the most common reasons why an unpleasant odor might come from your AC unit.
Mold and Mildew Growth
An AC unit is a breeding ground for mold and mildew growth. Air conditioners and ductwork provide dark spaces where mold can grow, along with organic material such as dust and debris. This environment allows mold and mildew to thrive with the addition of condensation from cooling coils.
Mold and mildew can grow in all kinds of HVAC units. While all types of molds can be a nuisance, black mold is a concern. Black mold can trigger allergy symptoms in some people, but it poses the greatest danger to those with preexisting conditions or the immunocompromised. The AC unit can blow black mold spores into your home, allowing the spores to take root in other parts of the house, including the carpet, walls, and furniture.
While a bad smell from an air conditioning system isn’t always mold, it is one of the most common causes. If your AC smells musty, one of your first steps should be to check for mold. If your AC does have mold, you’ll need professional HVAC services.
A trained technician will have the equipment and tools necessary to check for mold and remove it. Hiring a mold removal expert is the safest way to approach this situation. If you decide to remove mold on your own, wear goggles, safety gloves, and a face mask to avoid exposure to spores. Dispose of mold immediately in an approved dump site, and never keep mold anywhere near your home, people, or animals.
Dirty Air Filters
Dirty air filters can cause a smell similar to dirty socks or even a dead animal. A dirty air filter can lead to water droplets accumulating on the evaporator coils, which freeze as the AC unit’s refrigerant cools the air.
To safeguard against this problem, air filters should be changed regularly. Homeowners can do this task independently since changing an air filter is quick and easy. You can also have an HVAC technician perform regular maintenance on your unit, including air filter changes.
Frozen Evaporator Coils or Clogged Drain Line
Frozen evaporator coils or a clogged drain line can also cause a musty smell from your air conditioner. Frozen evaporator coils are relatively easy to spot. You might notice ice outside the refrigerant line or condensation and moisture around the air handler. If you see either of these, combined with a bad smell, turn off your thermostat and contact an AC repair technician. If you don’t see ice but still suspect that your unit could be freezing up, a technician can help troubleshoot the problem.
Air Conditioner Cleaning and Maintenance
Regular maintenance is essential for any household item to operate at peak capacity. Taking the time to clean and maintain your HVAC unit ensures it will work for a long time. It will also keep musty odors at bay. Here’s how to clean and maintain your air conditioner:
Remove any debris or foliage around the unit. Shrubs, leaves, and twigs can restrict airflow.
Vacuum the coil fins, which wrap around most of the outside of the unit, using a soft bristle brush attachment. Be careful not to bend the fins, which can cause restricted airflow.
After vacuuming the coil fins, clean them with approved chemicals and a garden hose. Disconnect the system from power before using liquid around the unit. Gently rinse away debris.
Clean the drain pan, which is located under the evaporator coil. Check for leakages and that the pan isn’t in danger of overflowing. Water in the drain pan is normal, but extreme overflow isn’t.
HVAC systems have different setups depending on their type. For example, window air conditioners allow water to evaporate in the pan quickly, while a central system has water droplets that drain out through pipes.
Make it a habit to change out the air filters after every routine cleaning. Make sure the filters you use fit your unit correctly and never cram in a filter that’s too large. It’s best practice to clean your AC coils at least once yearly, but some experts recommend twice yearly.
When To Get Professional Help
Some situations warrant professional assistance from an HVAC technician. Call a technician if you notice an unpleasant smell from your AC unit that doesn’t go away even after cleaning the unit and changing out the filter. Call a professional if you need help cleaning the unit. Bring in a technician as soon as possible if your AC makes any strange sounds in conjunction with a bad smell.
A licensed technician will thoroughly evaluate your system, checking parts such as the condensate drain line and AC vents and looking for mold or excess moisture. If the technician notices any mold spores or areas of concern, they can conduct a deep clean and restore your unit to a safe condition. A technician can check for other possible issues with your AC unit and address and fix them before they become significant problems that could compromise the safety of your unit.
Our Conclusion
Dirty air filters and mold or mildew growing around the unit can cause musty odors in your air conditioner. It’s important to diagnose and address a musty smell right away. In some cases, a musty odor can pose a health risk to occupants, such as mold growing in or around your unit. You can clean your air conditioner by following a few simple steps, but if you feel uncomfortable doing DIY maintenance on your HVAC unit, it’s time to call a professional. An HVAC technician can diagnose the musty smell in your AC unit quickly.
Perform regular AC unit maintenance, including changing the air filters regularly. Experts recommend doing a deep clean at least once a year, but you can thoroughly clean your unit before each new season starts. With some care and attention, your AC unit will last for years, ensuring your home remains comfortable and safe.
FAQ About Musty Air Conditioner Smells
How do I get the musty smell out of my air conditioner?
If your air conditioner has a musty smell, you can perform a few troubleshooting steps. First, check the air filter. A dirty air filter can often cause an unpleasant odor to come from an HVAC unit. Mold or mildew, which is common in most air conditioning units, can also cause a foul smell to circulate.
Why does my HVAC smell musty when I turn it on?
An HVAC system can smell musty when you turn it on due to mold or mildew, a dirty air filter, or some other issue with the internal components. If you notice a musty smell, address it immediately by inspecting the system or calling a licensed HVAC technician.
What is that bad smell coming from the air conditioner?
Many things can cause a bad smell coming from the air conditioner. Dirty air filters, mold or mildew in the unit, or an underlying issue with one of the components could be the culprit. Call an HVAC technician to evaluate your unit or look into it yourself.
What does mold in the AC smell like?
Mold in the AC smells musty, with many homeowners describing it as like old socks, standing water, or garbage. In some extreme cases, mold in the AC might smell rotten, like a dead animal or spoiled hardboiled eggs. If you notice a smell like this coming from your air conditioner, contact an HVAC technician immediately.
How often should I clean my air conditioner to prevent a musty smell?
Clean your air conditioner at least every year to prevent a musty smell. You can also clean it at the start of every season by cleaning the components and changing the air filters. If you feel uncomfortable cleaning your HVAC unit on your own, call a trained professional.
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