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8 Ways To Fix A Musty Air Conditioner

When your air conditioner is functioning properly, it shouldn’t create any sort of unpleasant odor in your home. If your Riverside, CA home constantly smells damp, dusty, or moldy, your cooling system may be to blame. The good news is that there are eight easy ways to both solve the problem and keep it from recurring.


Clogged HVAC filters inhibit airflow. As a result, air conditioners must work harder to pull air in and distribute it. When paired with limited air movement, this extra stress causes excess moisture in air ducts, and it creates the perfect conditions for mold development.

There’s also the fact that dirty air filters harbor dust, dander, fur, and other allergens and contaminants that they’ve collected over time. If you forget to change your HVAC air filter for too long, thick clumps of this debris can get blown off and distributed with your conditioned air.

HVAC air filters should be inspected once each month. Filter changes should be performed once every one to three months based on your home’s indoor air quality (IAQ), air conditioner use, and other factors. When you’re greeted by a strong, musty odor upon turning your AC system on, always check the air filter first.

It’s also important to make sure that you’re using the correct filter type and size. HVAC air filters are issued with maximum efficiency reporting value (MERV) ratings. The higher a filter’s MERV rating is, the more particulates it’s able to collect. High-rated filters can capture and retain smaller-sized particulates than standard air filters can. However, if you choose an option that’s rated too high, its enhanced filtration abilities could impede airflow, cause humidity problems, and create perfect conditions for musty odors. If you’ve recently upgraded your HVAC air filter, have us check it out to make sure that it’s a good fit for your HVAC system.


As warm air passes over an air conditioner’s evaporator coils, moisture and heat are absorbed, and condensation forms. This condensation drips down the evaporator coil into the condensate pan. It is then routed out of the home via the condensate drain.

If the condensate drain is ever clogged or slow-moving, bacteria, mold, and other pathogens can flourish. When paired with stagnant water, these germs will fill your home with a pungent, lingering smell. We can clear your condensate drain as needed. We can also check the drain pan for cracks, holes, and other structural damage.


Excessively dirty evaporator coils can also lead to funky AC odors. AC coils are where heat transfer takes place and thus, they’re constantly subjected to the unfiltered outside air that gets pulled in. Over time, this can leave them coated in dirt, pollen, and other elements. Given that moisture is constantly being produced here during heat transfer, dirty evaporator coils are often riddled with odor-causing germs. During routine AC maintenance, your air conditioner’s evaporator coil and condenser coil will both be thoroughly inspected and cleaned.


Most homes only need their air ducts cleaned about once every three to five years. However, if you have one or more pressing IAQ concerns, you might want to schedule these services more often. HVAC air duct cleaning eliminates trapped particulates that have bypassed the HVAC air filter, or have found their way in via rips, tears, or other structural damage. During duct cleaning service, all internal build-ups of debris are removed, and structural issues are identified and repaired.


If you have an excessively dirty air filter, you can expect to find the same lint-like build-ups that accumulate on these components at all air registers, vents, or grilles. You can wipe these features off with a soft, damp cloth. If necessary, you can also remove vent covers and grilles, and gently suction out debris with your vacuum cleaner’s hose and attachments.


If you’re handy, there’s a fair amount of AC maintenance that you can safely do on your own. Regularly changing your HVAC air filter and periodically wiping down HVAC air grilles will keep your indoor air quality high. However, air conditioners also require a number of yearly maintenance tasks that homeowners shouldn’t perform. To keep your AC in top condition, you need the help of a professional.

If you’ve been neglecting annual AC tune-ups for quite some time, this may be the source of your trouble. During AC maintenance service, we inspect condensate pans and condensate drain lines, clean AC coils, remove blockages, and ensure balanced humidity and airflow. All these things contribute to healthier and fresher-smelling indoor air, and better overall AC performance. Our AC tune-up service offers the perfect opportunity to identify the underlying causes of unpleasant AC odors and resolve them.


At times, air ducts may be harboring pests or the carcasses of animals that have wandered into these systems before getting trapped. Raccoon, mice, and other small to medium-sized animals frequently enter air ducts in search of shelter and warmth. If your air ducts smell especially rank or if you notice strange noises coming from your ductwork, you should contact a pest control service.

Pest problems in HVAC air ducts are common in homes that are struggling with pests in other areas. If you’re currently battling a rodent infestation in your basement or attic, you can’t assume that your HVAC air ducts are unaffected. Pest control companies can identify viable points of entry in your ducting, remove dead or dying animals, and establish an ongoing pest management plan for prevention. For problems like these, we’re here to help too. We can deodorize and disinfect all affected areas, shore up access points, and repair damaged ducting or other damaged HVAC features.


Among the most common causes of musty AC smells is excess moisture. This could be excess moisture in your air ducts due to a dirty, blocked filter, or excess moisture as the result of an obstructed condensate drain. However, in some instances, high levels of indoor humidity are to blame for the moisture gathering in your system. You may have an especially large household with lots of active bodies, poor ventilation, under-performing exhaust fans, or other moisture-generating issues that are specific to your home or family.

For issues like these, whole-house dehumidification could be the best solution. In instances in which indoor air is notably low in quality and persistently foul-smelling, air scrubbers, air purifiers, or media filters might be required. We can help you find the right integrated HVAC accessories for improving your IAQ. For stubborn AC odors that aren’t responsive to other solutions, call us for an indoor air quality consultation.

We’ve been proudly serving residents of Riverside, CA, and the surrounding area since 2010. We offer heating, cooling, and indoor air quality services. We also provide smart thermostats and ductless mini-splits. If you need help fixing your musty air conditioner, give Dragonfly Heating & Cooling a call.

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