Why Does My AC Smell Musty? Common Causes and Fixes for Tampa Homes
Musty AC smells are common in Tampa, especially during our humid summer months. If your air conditioner smells stale, damp, or earthy, it’s likely due to moisture buildup that’s allowing mold or mildew to grow in your HVAC system.
That odor is more than just unpleasant—it could be affecting your indoor air quality and your family’s health. In this article, we’ll cover what causes a musty AC smell, when it’s a serious issue, and how to get rid of it for good.
What Causes Musty Smells in Your AC?
Musty odors usually stem from one or more of the following moisture-related issues:
- Clogged or Dirty Drain Pan
The drain pan beneath your evaporator coil collects condensation. If it's dirty or blocked, standing water can lead to mold growth and unpleasant smells. - Dirty or Damp Air Filter
A neglected air filter can trap dust and moisture, turning it into a source of musty odors each time your system kicks on. - Stagnant Air in Ducts
Poor airflow or leaky ducts can trap humid air. Without proper circulation, mold and mildew can develop inside your ductwork.
Is It Just Annoying—Or Potentially Harmful?
Sometimes, a musty smell is just trapped moisture and may go away on its own. But other times, it’s a warning sign of mold inside your HVAC system. Here's how to tell:
- Mild Moisture Issues
If the smell only appears briefly when the AC first turns on, it might just be humidity or standing water in the coils or pan. - Mold Contamination
If the smell lingers, intensifies, or is accompanied by allergy symptoms (sneezing, coughing, irritated eyes), mold is likely the culprit. Mold spores can negatively impact your respiratory health.
DIY Tips to Eliminate Musty AC Smells
Try these simple fixes before calling a professional:
- Replace the Air Filter
Dirty or damp filters are a leading cause of musty odors. Swap it out with a clean one. - Check for Standing Water
Inspect the area around the drain pan and coils. Clear any visible water and make sure the drain line isn’t clogged. - Use Fan-Only Mode
Running your HVAC fan without cooling helps dry out moisture that may have built up inside the system.
When to Call Millian Aire
If the musty smell keeps coming back—even after replacing your filter and checking for moisture—it’s time to bring in the professionals. Call us if:
- The odor persists or worsens
- You spot mold in or around the system
- The air quality in your home feels stale or triggers allergy symptoms
How UV Lights Eliminate Mold and Odors
UV lights are one of the most effective tools for stopping mold and bacteria before they spread.
- Installed inside your AC—typically near the evaporator coil
- Shine continuous ultraviolet light on moisture-prone components
- Neutralize mold, mildew, and bacteria before they cause musty odors
At Millian Aire, we install advanced UV light systems to help keep your AC clean, fresh, and mold-free. Learn more about our UV Light Services →
Control Moisture with Whole-Home Dehumidifiers
Florida humidity creates the perfect environment for musty odors. A whole-home dehumidifier removes excess moisture from the air before it settles into your HVAC system.
- Built into your HVAC for full-home coverage
- Keeps humidity between 40–60%
- Reduces mold, mildew, and musty smells
Add Oxidation Units for Next-Level Air Purification
Oxidation units go beyond basic filtration by neutralizing odors and airborne contaminants at the molecular level. When paired with UV lights and a dehumidifier, they offer full-spectrum odor protection.
Don’t Let a Musty AC Smell Linger
Musty smells won’t go away on their own—and they often signal deeper issues inside your HVAC system. Millian Aire offers:
✅ UV light installation to kill mold
✅ Whole-home dehumidifiers to control humidity
✅ Duct cleaning & AC maintenance to keep air fresh
📞 Call (727) 233-5566 or schedule your service online to enjoy cleaner, fresher air year-round.