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How to Get Rid of Musty Odors in Your Air Conditioner?

Ty Schaedel • 29 May 2024
A woman is covering her nose in front of an air conditioner.

Does your air conditioner smell musty?  

We’ve all been there — walking into a room only to be greeted by a musty smell that seems to cling to the air. It’s not just unpleasant; it makes your entire home feel less inviting. 

If you face the dreaded air conditioner smells musty situation, you are not alone. This is one of the common AC air flow woes. Its origin can be traced back to the key culprit – lack of regular maintenance. Whether it’s from trapped moisture, mold growth, or accumulated debris, a musty smell demands immediate action.

But don’t worry, we’re here to help you. 

Let’s find out what causes your air conditioner to smell musty and how you can prevent it.

Understand the Causes of Musty Odors in Your AC Unit

Air conditioners are not supposed to have an unpleasant odor. If your air conditioner smells musty, smoothing is wrong with it. There is no need to freak out if your air conditioner smells musty. It’s possible to eliminate these musty odors and get your AC back to blowing cool and fresh air.

As the saying goes, “Prevention is better than cure.” So, why wait until your air conditioner smells musty? You can easily prevent those unpleasant odors in your air conditioner.

Here are the top five reasons for this unpleasant smell and what you can do to fix it:

1. Clogged Air Filters

Two air filters are sitting on a wooden floor next to each other.

Your air conditioner uses filters to maintain a clean airflow throughout your home. However, these filters accumulate dirt, dust, and other debris over time. Without regular cleaning, these air conditioner filters get clogged and lose their efficiency. The more your air conditioning system works, the faster these filters can get clogged. 

A clogged air filter reduces the airflow, which makes your air conditioning system work harder. Worse still, clogged filters are a home for dampness. As the dampness settles in the filters, your air conditioner smells musty. In other words, filters are the first thing you would want to check if your air conditioner smells funny.  

Here’s what you can do:

Clean or Replace Filters

A man is standing on a ladder cleaning an air vent.

If your air conditioner smells musty, first check your filters. Dirty filters often circulate unpleasant smells when you turn your AC on. If they are dirty, clean the filters thoroughly using a mixture of vinegar and water or a plumbing snake to clear the blockage. But if they are damaged, replace them with new filters. Other than eliminating musty smells, this also improves airflow significantly.

2. Stagnant Water

The drip pan or condensate drain line often gets overlooked during regular maintenance. However, it has a critical job – removing the moisture from your air conditioning unit. But when it gets clogged , the drain line quickly becomes a breeding ground for mold, mildew, and bacteria.

These three elements are notorious for making air conditioners smell musty. The only way to overcome this problem is to check your drainpipe regularly. Also, check the insulation and sealing around your air conditioner. Remember, a properly sealed and insulated AC unit keeps moisture buildup at bay.

A close up of a pipe with water dripping from it next to an air conditioner.

Here’s what you can do:

Clear Out Stagnant Water

As mentioned, a clogged drainpipe is one of the main causes of musty odors. Check your drain line carefully for clogs or pooled water. Clean it out immediately. You can use a mixture of warm water and vinegar to flush out any blockages. Be careful not to use too much force, as this can damage the pipes. Keep the drain line dry and clean throughout the year to prevent musty odors. 

Address Leaks or Malfunctions Promptly

Address any leaks or damage in your air conditioning unit as soon as they are detected. Timely repairs not only prevent musty odors but also increase the lifespan of your AC. Have an HVAC pro check and repair your air conditioner at least once every six months. However, get professional help immediately if your AC suddenly stops working.  

3. Mold and Mildew Growth in the Evaporator Coil

Mold and mildew thrive in moist environments. During the fall and winter, when you don’t use your air conditioner as much, it gathers dirt, dust, and other debris. This bio growth, combined with a clogged drain line or unnoticed leaks, is perfect for moisture buildup. Mold and mildew lay down their roots as soon as moisture starts to build up in your AC. 

A man is spraying water on an air conditioner in the grass.

These microorganisms produce spores, which are one of the common causes of musty air conditioning smells. These spores also have potential health risks , especially for people with weakened immune systems or respiratory conditions.

Regular inspections for excess moisture buildup and leaks are critical in preventing mold and mildew. These steps will safeguard both the indoor air quality and your health.

Here’s what you can do:

Monitor Humidity Levels

Florida’s humid climate, with average relative humidity levels exceeding 70% , creates ideal conditions for mold growth.  That means you need to monitor the indoor humidity levels. It’s best to keep indoor relative humidity between 45%- 55%. Bacteria, viruses, mold, mildew, and some pests, like dust mites, often begin to thrive outside this range.

4. Dirty Air Ducts

Like the drain line, it’s easy to overlook the condition of your air ducts. However, they are integral to the overall performance of your air conditioning unit. Over time, dust and debris accumulate in your air ducts. If there are leaks, the ductwork turns into a haven for mold and mildew.

This can make your air conditioner smell musty. The Environmental Protection Agency (EPA) recommends that homeowners consider having their air ducts cleaned by a qualified professional, as improper cleaning can actually worsen indoor air quality. This can help you fix and prevent AC bad smells and boost the overall efficiency of your air conditioning system.

Here’s what you can do:

Inspect and Clean Air Ducts

A man is cleaning an air vent with a brush.

This may seem like a daunting task. However, your air ducts need to be clean. Air ducts deliver the cooled air from your air conditioning unit. Over time, these ducts can accumulate dust, debris, and even mold. Without regular cleaning, these ducts can lead to musty odors. They will carry this odor and the fungal spores everywhere. 

You can inspect and clean the ducts yourself. However, we recommend hiring a team of professionals. For one, this will save you from a lot of hassle. Secondly, professionals can do a better job without compromising safety. It is particularly important if your air ducts were last cleaned months or years ago. 

5. Broken AC Components

All components in your AC must work in sync. There is no other way to fight the scorching Florida summers. But like anything else, ACs also undergo wear and tear over time. If one or more of your AC comments are damaged, it can lead to moisture buildup and make your air conditioner smell musty.

For example, a Freon leak can prevent your air conditioner unit from dehumidifying the air. That may lead to higher moisture levels, mold and mildew growth, and unpleasant musty odors. Regular maintenance is necessary to keep these air conditioner smells in check. 

A man is working on an air conditioner with a hose attached to it.

Here’s what you can do:

Schedule a Professional AC Repair

Sometimes, your air conditioner smells musty, even after changing filters or cleaning the drain. This might indicate a deeper issue, which only a professional AC repair contractor can fix. Regardless, you should schedule a professional tune-up at least once a year. 

Qualified and trained technicians can typically find issues your untrained eyes might miss. They also check your system thoroughly. It helps you identify the problem quickly and accurately. And more importantly, professional tune-ups can help extend the life of your AC. So, this is as much about eliminating musty odors as it is about running your AC smoothly for years.

Two men are working on an air conditioner outside of a house.

Schedule Regular Maintenance

AC maintenance is not expensive, but neglect is. Ignoring regular maintenance can turn small issues into major and costlier problems down the line. It might cause your AC to freeze suddenly on a hot summer day. You should check it regularly to avoid this discomfort and musty odors.  

These routine inspections involve visually checking the mechanical parts. Look at different parts of your air conditioner for potential wear and tear. Check if all components are working at their peak. If not, call a licensed HVAC contractor to have a look. 

The Wrap Up

With the summer ringing all its bells and whistles, the last thing you want is an air conditioner that smells musty. It’s not just uncomfortable but a potential health hazard. The musty smell comes from fungal spores and other microbial growth in your AC, which can lead to many health issues. The good news is regular maintenance can help you eliminate this unpleasant smell. So, try these tips to keep your AC from smelling funny. 

And if you need help, we are just a phone call away. B&J Heating and Air offers top-notch AC repair services. Contact us online or call (727) 281-8718 to schedule a visit.

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