Why Does My AC Smell Musty? Causes & How to Fix It

Indiana gets a fair amount of snow, but summers are when homeowners see the most precipitation. With summer rain and heat comes humidity, which means your AC might start to smell musty.

The experts at Dugan Air Heating & Cooling have some helpful tips and information if your AC smells musty, so you can enjoy a clean-smelling, healthy home before the summer hits. Discover some common causes of musty smells, how to eliminate musty AC unit odor, and more.

Common Causes of a Musty Smell in an AC

The musty smell from your AC unit may be caused by a variety of issues. Here are some of the most common causes of a musty odor.

Mold and mildew

An accumulation of moisture creates the perfect breeding ground for mold and mildew to grow and thrive. AC units remove moisture from the air, which can start to accumulate in your drain pan, air ducts, or evaporator coils.

If your air conditioner isn’t properly maintained or cleaned regularly, mold and mildew can start to grow, creating an unmistakable musty smell. Mold in your AC is a health hazard that requires prompt attention.

Dirty filters

The air filter in yourHVAC system is designed to trap particles like dust, pollen, and pet dander. However, a clogged or dirty filter can cause moisture buildup, leading to musty smells. A clogged air filter also restricts airflow, which affects your air conditioner’s efficiency and increases your energy costs. Over time, dirty filters can lead to a stressful system breakdown.

Other common causes

Moisture and mold/mildew are the most common causes of a musty smell in an AC, but inadequate ventilation can also contribute to the unpleasant odor. Constant temperature fluctuations may lead to excess condensation and mold growth. If your blower wheel is dirty, grime will build up, creating a musty smell. A dead rodent or other pest stuck in your ductwork or HVAC system will cause a musty odor. 

Steps To Eliminate Musty Odors From Your AC

How do you get rid of an AC smell? Follow these steps to help eliminate unpleasant odors from your air conditioner and home: 

• Step one: Clean or replace the air filter to increase airflow and prevent moisture and bacteria buildup.

• Step 2: Clean your evaporator coils by removing dirt and debris with a mixture of warm water, mild detergent, and a soft cloth or soft-bristled brush.

• Step three: Inspect your drain pan and drain line for clogs, and empty the drain pan if it’s full of water.

• Step four: Make sure your air vents are clear of obstructions and remove furniture or other objects blocking them to improve airflow.

• Step five: Seal leaky ducts and repair cracked or broken ductwork to fight moisture buildup and musty odors.

• Step six: Contact the pros at Dugan Air to schedule professional duct cleaning to remove dirt and persistent musty odors. 

• Step seven: Use a mixture of vinegar and water to deodorize your AC unit and place an open container of baking soda nearby to absorb excess odors.

• Step eight: Use a dehumidifier in your home if the humidity levels are too high and are contributing to a musty smell.

• Step nine: Run your fan on low for a while to dry out your system after cleaning.

Health Risks Associated With Musty AC Smells

Most musty AC odors are caused by mold or mildew, which may be dangerous to your health. Health risks associated with a musty AC include: 

• Respiratory issues: Mold spores and mildew can irritate the respiratory system, causing symptoms such as coughing, wheezing, and shortness of breath.

• Worsens allergies: If you have allergies, exposure to mold can trigger an allergic reaction and worsen your symptoms.

• Affects those with asthma: People with asthma may experience more intense and frequent breathing issues due to mold or mildew in the air.

• Increased infection risk: Mold creates a friendly environment for bacteria and other microorganisms, which increases the risk of respiratory infections, especially if you already have a weak immune system.

• Chronic issues and other symptoms: Exposure to mold over a long period can lead to chronic respiratory conditions and cause symptoms such as dizziness, headaches, fatigue, and nausea. 

Preventing Musty Odors in Your AC

One of the best ways to avoid dealing with musty odors is to prevent them from occurring in the first place. Follow these tips to help prevent musty odors in your AC.

Practice regular maintenance

Routine maintenance — including changing your HVAC air filter every 30, 60, or 90 days — is a good way to prevent moisture buildup and musty odors. Have your system and air ducts inspected and cleaned every season to remove dirt and buildup. Clean your evaporator coil regularly to remove excess grime, and keep your condensate drain line clear and free from clogs. Doing this prevents water from pooling, which contributes to mold growth.

Address moisture issues

If you have a high humidity level in your home, use a dehumidifier to keep it to a minimum and prevent mold and mildew growth. Make sure your home has proper ventilation, especially in the kitchen and bathrooms, to keep moisture levels low. If your air ducts are leaking, have them sealed and repaired to stop moisture buildup and unpleasant musty odors. 

Use tools to remove odors

Several products help to keep the air inside your home fresh and clean, including air purifiers that use activated carbon filters to remove contaminants and odors. Place baking soda in a bowl near your AC unit to absorb moisture and odors. Clean your air vent slats regularly to remove debris and dust, which may contribute to musty smells.

Contact Dugan Air for a professional AC odor removal service, such as a special UV light installation that helps kill mold and mildew spores. 

When To Contact a Professional

While the above tips are helpful for preventing and removing musty AC smells, there may come a time when it’s best to contact a professional. Consider calling Dugan Air for help with your musty AC odor issues when you notice the following:

• The odor won’t go away: If the musty smell remains long after you’ve tried our troubleshooting tips, you might have a more serious underlying problem that requires professional help.

• Visible signs of mold: If you can see mold growing in or around your AC unit or air vents, you have a mold problem that requires professional removal and remediation.

• Low airflow: Weak or no airflow after changing the filter may indicate a more complex issue that requires help from a trained HVAC professional. 

• Strange noises: Unusual sounds, such as rattling, hissing, or groaning, accompanied by a musty smell, may indicate a problem with the AC system components.

• Health issues: If you or someone in your family experiences ongoing mold-related health issues, have the problem addressed as soon as possible to keep everyone healthy.

Contact Dugan Air for AC Services

The team at Dugan Air Heating & Cooling blends high standards of service with a friendly, community-centered approach. We aim to be the go-to choice for Indiana homeowners seeking both comfort and a personal connection. Contact us today if you need help addressing musty AC smells or want to schedule an HVAC service.