Why Does My AC Smell Musty?

Do you find yourself plugging your nose when your Phoenix AC is running? Does it smell like dirty gym socks or some other musty, stale, and unpleasant odor? If your air conditioner is giving off a damp moldy smell, you should not ignore it, something is wrong. We are going to review some of the main causes for the stuffy odor and help you answer the question, “Why does my AC smell musty?”

Why Does My AC Smell Musty?

According to Merriam-Webster, “musty” is defined as “impaired by damp or mildew”. Dictionary.com defines it as, “having an odor or flavor suggestive of mold, as old buildings, long-closed rooms, or stale food”. Cambridge Dictionary provides the definition as, “smelling unpleasantly old and slightly wet”. Basically, no matter how you put it, if something smells musty, it is not an enjoyable smell, especially one that you want to have in your home.

If you have to ask, “Why does my AC smell musty?” and there is no obvious cause, there is likely a problem with your HVAC system. We review some of the most common causes, of the less than desirable odor, below.

  • Leaky or Dirty Air Ducts: Air ducts play a critical role in your Phoenix area home. They circulate air from your HVAC system to all rooms in the house, helping to maintain comfort for your family throughout the year. Over time, mold and mildew, and other odors can get trapped in your ductwork leading them to be redistributed throughout your home. If you smell something unpleasant when your HVAC is running, it can be from your ducts.
  • Unclean Evaporator Coil: Your AC works by removing heat and humidity from your home. Essentially, the evaporator coil absorbs the warm air and moisture, cools the air and evaporates the moisture, and then cycles the dry air back through your home. If your evaporator coil is frozen or unclean, it will not work as intended, and the moisture will not evaporate, causing mold and mildew to develop.
  • Clogged Drain Line: When enough condensation forms on the evaporator coil, it drops into a drain pan and then exits out a drain line. If the drain line gets clogged, then water (usually dirty) can back up into the drain pan and line. Any sitting moisture can be a breeding ground for mold and mildew and be the reason you are asking, “Why does my AC smell musty?”
  • AC System is too Large for Your Home: While you may think bigger is always better, when it comes to your home’s HVAC system, that is not the case. If the system is too large for your home, air can be cycled through your home too quickly, resulting in improperly dehumidified air going through your unit and home, and leading to excess moisture to develop. Contact a local Phoenix AC expert to help you find the right sized unit for your home.

Why Should you Address Your AC’s Musty Odor?

While we have reviewed some of the most common causes for why your AC could smell musty, you may still be wondering why, if you can stand the smell, if you should even be concerned. The obvious reason you should have the problem addressed is because if your air conditioner is putting out a stale aroma, there is likely a larger issue, and if it’s not resolved, it can eventually lead to a costly breakdown and repair.

One main reason to have the musty odor resolved that many people don’t think about, is you and your family’s health. The odor is likely due to mold and mildew being somewhere throughout your central air system and exposure to damp and moldy environments may cause a variety of health effects, or none at all, depending on the person, and the amount of mold in the environment.

According to the EPA, molds produce allergens (substances that can cause allergic reactions) and irritants. Allergic responses include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash. Allergic reactions to mold are common. They can be immediate or delayed. Molds can also cause asthma attacks in people with asthma who are allergic to mold. In addition, mold exposure can irritate the eyes, skin, nose, throat, and lungs of both mold-allergic and non-allergic people.

Phoenix AC Professionals

The best way to avoid having to ask, “Why does by AC smell musty?” is by keeping up with proper AC maintenance. Arizona Comfort Specialists can help with a cooling tune-up or other seasonal HVAC maintenance.

Should you find yourself with a problem, Arizona Comfort Specialists are here for you. With decades of experience under our belts, as a full-service air conditioning company in the Phoenix Area, we put your home and comfort first. Contact us today.

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If you are looking for a reliable, honest A/C company with knowledgeable technicians and great service, this company is the best! So thankful we found them! Thank you for all your hard work!
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My A/C quit working and needed a new part. I was very happy 😃 when the owner came out the next day , found the problem, replaced a wire and the part was under warranty 😃 I now have cool air again 😃
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Arizona Comfort Specialists is top quality with A.C. work. I only needed them for that so far. Bryan did an outstanding job with identifying the problem.
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Az Comfort Services did a great job inspecting our airconditioner. Their technician was very knowledgeable and did not try to "oversell" us. Our airconditioner is 17 years old! He cleaned it and made some minor repairs and said he hoped it lasted another year. I highly recommend Az Comfort Specialists.
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Aaron Came over to one of our houses and got the tree roots out of the drain impressed by his knowledge his candor and just his overall friendliness and professionalism.... We are also having them do our AC install👍👍 Justin has been amazing coordinating everything for all of our needs very impressive😎😎 If you're looking for professionalism friendliness and decent pricing this company is amazing.... please hire them🌴🌴🌴 You won't be disappointed!!
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Great service on our HVAC system. The service technician kept us informed about what issues they identified and what the options were to correct them.
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Aaron was very professional, did the job efficiently, and was friendly and informative of the process. Highly recommend.