While a temporary musty smell from your AC vents after winter in Amarillo is normal, a persistent odor can hint at underlying issues. If your AC smells musty and circulates unpleasant odors throughout your home, it can be a sign that it harbors mold and mildew and sends spores and other allergens into your rooms. Here are some of the possible reasons why your AC smells, what you can do to prevent it, and when to call in the HVAC experts at Frank’s.
5 Possible Reasons Why a Musty Smell is Coming from Your Air Conditioner
When your AC smells musty, a few factors may be to blame.
1. Your condensate drain pan is full
The condensate drain pan catches the humidity your AC removes from your home’s air and sends the excessive moisture through a drain tube. Drain pans can sometimes clog and fail to properly drain water, leading to mold growth, especially if not effectively maintained. If you notice an odor that smells like dirty socks, it might be time to clean, empty, or replace the drain pan.
Depending on the specific model and type, AC systems vary in terms of the number of drain pans, where they’re located, and how to remove them. During routine spring AC maintenance, your HVAC technician will inspect and clean the condensate pan.
2. Your condensate drain line is clogged
The condensate drain line is the pipe that routes water from the drain pan to the outside of your home. Condensate drain lines easily clog with bacteria, dirt, and other debris, and when combined with moisture, they become the ideal environment for mold growth.
You can clean your condensate drain line yourself between routine maintenance with just a few household supplies and the following steps:
- Step one: Shut off the AC’s power at both the thermostat and the breaker switch.
- Step two: Locate the T-shaped pipe fitting attached to the indoor drain line. Remove the cap.
- Step three: Remove any obvious and accessible blockages by hand and pour distilled vinegar or another mild cleaning solution into the line. Flush the line with water to move any residual solution and debris, and return the cap to the fitting.
If a simple cleaning isn’t enough to clear the line, the pros at Frank’s will unclog it in no time.
3. You have excess moisture in your ducts
While a small amount of moisture in your ducts is harmless, excessive moisture can lead to high indoor humidity — the ideal condition for mildew, mold, and musty odors. In addition to a musty or moldy odor when your AC is running, signs of excessive moisture in your ducts include:
- Visible mold or mildew on the duct surfaces.
- Water stains on the wall or ceilings around your air vents.
- Visible condensation on the exterior of your ductwork.
- A noticeable increase in indoor humidity levels.
If you suspect excess moisture in your ducts is responsible for the musty smell, a few DIY fixes might help:
- Regulate humidity levels with a dehumidifier — the ideal home humidity level is 30% to 50%.
- Replace your air filter when it’s dirty — at least every three months.
- Add insulation to metal ductwork to help prevent condensation from building up.
If the problem persists, a professional duct cleaning may be in order.
4. Your air filter is dirty
Without proper maintenance, air filters can clog and eventually accumulate mold. Dirty water can also freeze on the evaporator coils, producing an unpleasant musty smell from your air conditioning unit.
During a routine maintenance check, an HVAC technician can replace your air filter, check for leaking refrigerant, and look for loud noises coming from your AC. If you suspect the evaporator coils are moldy, frozen, or both, it’s time to schedule maintenance.
5. Other causes to consider
Here are some other causes for why your air conditioner smells musty:
- High indoor humidity levels that create excess moisture in the system
- Buildup of dirt, dust, or organic debris inside the air handler, which can lead to bacterial or fungal growth
- An oversized AC unit that short-cycles and doesn’t properly dehumidify the air
- Infrequent AC use or extended periods of inactivity that allow moisture to accumulate
- Aging HVAC components that are less effective at managing moisture and airflow
How to Get Rid of the Smell in Your Air Conditioner
Getting rid of the musty smell in your AC requires identifying and eliminating the source of the odor. Here’s a step-by-step guide to help you tackle the issue:
- Step one: Replace or clean the air filters (check them monthly and replace them every 1–3 months).
- Step two: Clean the evaporator coil (if you’re unsure how to access or clean it, call a professional HVAC technician).
- Step three: Unclog and clean the drain pan & drain line (use a mixture of vinegar and water or a commercial cleaner to clean the pan).
- Step four: Inspect and clean ductwork (if you see signs of mold or smell mildew at vents, schedule a professional duct cleaning).
- Step five: Schedule a professional maintenance visit with Frank’s.
Prevent Musty Smells With Routine Maintenance
After Amarillo’s chilly winters, spring is the best time to schedule your annual tune-up, which includes a thorough A/C cleaning and duct inspection and helps identify moisture issues before they become a problem for your health and your home.
There are many ways you can keep your AC working in peak condition in the summer, but our friendly technicians will replace your air filter and leave you with a supply for the cooling season. Staying on top of preventative maintenance allows your system to perform effectively and efficiently, saving energy costs and promoting a healthier indoor environment.
What To Do if Your AC Smell Won’t Go Away: Call Frank’s!
Nobody likes a musty smell circulating throughout their home, especially when it may be caused by mold. Mold reduces indoor air quality, can reduce system efficiency, and can lead to higher utility bills.
If your air conditioner smells musty, call Frank’s Repair Plumbing. We’ve been serving the Amarillo area for more than 70 years, and our friendly, knowledgeable technicians are happy to address your HVAC concerns and prevent future issues. Contact us today and learn why we’re the go-to choice for HVAC services in the Texas Panhandle.
Frequently Asked Questions
Why does my AC smell musty only when it starts?
If your AC smells musty only when it starts, it’s usually due to moisture or mold buildup on components like the evaporator coil, blower fan, or inside the ducts. This musty smell can also happen if the air filter is dirty or if the system hasn’t been used in a while, allowing moisture and dust to settle. Cleaning the filter, coils, and drain pan — and running the fan regularly — can help eliminate the odor.
Can a musty-smelling AC make you sick?
Yes, a musty-smelling AC can potentially make you sick, especially if the odor is caused by mold, mildew, or bacteria growing inside the system. When mold spores or bacteria are circulated through your home’s air, they can trigger allergy symptoms, respiratory issues, or asthma flare-ups, particularly in people with sensitivities.
How often should I clean my AC to prevent odors?
Basic cleaning (like filter replacement) should happen every 1 to 3 months. Deeper cleaning, including coils and drain lines, should be done yearly.
