Air Conditioner Smells Musty: Causes and Reasons

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August 1, 2022

You notice an unpleasant odor coming from your air conditioner, but you can’t seem to identify its source. Perhaps it’s mold, dust, or your imagination. If your air conditioner smells musty, there are many potential causes.

TemperaturePro Orlando is Central Florida’s leading HVAC company, with decades of experience diagnosing and fixing cooling units in the Sunshine State. Our reliable AC service company in Orlando uses industry-leading techniques to resolve your air conditioning unit problems quickly and effectively. 

Below are some potential causes for that musty smell coming out of your air conditioner. 

Your Air Ducts Have Mold on Them 

If you’ve noticed an unpleasant musty smell coming from your home’s air conditioning, there may be a mold or mildew problem. This odor’s potential cause is the growth of mold or bacteria in the ducts, which can be challenging to detect without proper testing.

A warm, moist environment can lead to the growth of mold and mildew. In addition, these organisms prefer a dark, moisture-rich environment. 

If you have a leaky roof, water will flow into the attic and concentrate there — this is also true for your air ducts. In addition, air leaks and drafts can bring in moisture and mold spores.

Evaporator Coils are Messy

If your air conditioner smells musty, there is a good chance that the evaporator or condenser coils are dirty. HVAC professionals know that air conditioners are prone to dirty coils. The coils are constantly in contact with the condensation that forms outside the unit. The moisture can combine with dirt and other pollutants to create a musty smell. 

Wrong Unit Size 

Having the wrong size air conditioning unit for your home or office can create a musty smell. A more powerful unit may pump cooled air through the system too quickly, failing to remove enough humidity from the air as it enters your inside space.

By contrast, an air conditioning system that is too small may not be able to effectively cool the space, leading to a hot and humid interior environment. If you can’t cool the space, mold, dust, allergens, and other air contaminants can create a musty odor.

Dirty Filters

A dirty filter will cause your AC to work harder to cool down the room, creating an unpleasant smell. Dirty filters can also affect your system’s ability to filter out allergens and other pollutants. If you suspect your filter is dirty, take some time to clean it or call in a professional.

Air Duct Leaks 

A leak is one of the most common causes of a musty odor coming from your AC. Leaks can come from anywhere in the air duct system – from the registers, vents, or even the AC unit itself. If you notice a musty smell coming from your home, call a professional to inspect your unit for a leak. 

AC Maintenance Services 

If your Orlando, FL, air conditioner smells musty or to learn more about the summer AC problems you may encounter, call TemperaturePro Orlando at (407) 225-8903. We can send a repair professional to your home or business in Orange County, FL.