May 11, 2021


Dirty AC in St Louis, Missouri -->

Air conditioning systems eliminate moisture from living space and filter air pollutants before they can get indoors. However, if you don’t schedule routine maintenance or clean your air conditioning unit frequently, it can cause your indoor air to become stinky. If your AC unit emits a foul odor, there could be several issues at play. Here are some reasons why your air conditioner smells and how to alleviate the problem in your home.

1. Frozen Evaporator Coils

An air conditioning unit works by absorbing the warm air inside your house, removing moisture from it, and cooling it down before cycling it back into the house via the return vents. Good airflow is essential for the entire process, which means your unit should have clean air filters.

Debris, dirt, and other pollutants usually block airflow through air filters, forcing the water drops from moist indoor air to accumulate on the coils. The water collecting on the unit’s evaporator coils will then freeze as the refrigerant cools down the air. That is where the significance of changing filters at home is realized. Replace or clean your filters more regularly to prevent the evaporator coils from freezing and emitting unpleasant odors.

2. Central Motor Leaks

Although central air conditioning units do not depend on gas to function, you might experience an exhaust smell due to damage to the unit’s inner motor. This AC odor might also indicate a wiring problem or an overheating motor.

If you notice a smell, deactivate the power to your AC unit in the breaker panel to prevent further damage to your system. If the exhaust odor does not disappear, contact a certified AC technician immediately. Unpleasant smells might also indicate hardware or parts in your HVAC unit that need to be replaced.

3. Condensate Drain Clogs

Unpleasant smells in your AC can also be caused by clogs in the drainage system of the condensate. The cooling process generates condensation as the air gets dehumidified. The condensate drain handles that moisture and eliminates it from the air conditioning unit.

Clogs can easily form in the unit’s drip pan as dirt, dust and other pollutants accumulate. Mold and algae can also develop in the drip pan, clogging it and stopping drainage. Blockages can also develop down in the drain line. Clear the condensate drain line and the drip pan to eliminate all clogs and treat them with algaecide to avert future growth.

4. Excess Moisture in Vents or Ductwork

Drainage leaks that go unnoticed or high humidity levels can cause excess moisture to accumulate inside vents and air ducts. If you turn on your air conditioning unit and notice a musty odor, there is a high probability that mildew and mold have spread inside the air ducts.

Keep in mind that exposing your family to mold can lead to upper respiratory health complications. Therefore, you need to contact a certified HVAC technician immediately to have the vents and ductwork repaired and cleaned to eliminate the musty smell.

5. Circuit Panel or Motor Short

The chances of circuit panel or motor shorts increase as your air conditioning unit ages. If your AC emits an odor that resembles gun powder or fireworks, contact an AC technician immediately. Early intervention can help prevent costly repairs to AC components.

6. Incorrect Sized AC

You need the right-sized AC for it to work properly. If the unit is extremely large for your house, the air will cycle fast throughout your home. That means dehumidification won’t take place completely, leading to excess moisture in your home.

The wrong size AC system might also make it susceptible to turning off and on regularly, causing premature failure and wear and tear. HVAC sizing depends not only on the square footage of your house but also on the insulation type, local climate, ceiling height, and the total number of persons living within the home. Have an AC-certified professional check to ensure your AC is the correct size for your home.

Final Words

Like any other AC issue, one of the best ways to prevent your unit from emitting foul odors is to schedule routine maintenance every year. Contact Scott-Lee Heating Company today if your AC is producing an awful smell. Whether you need AC replacement, repairs, or servicing, our technicians can get the job done fast to restore a clean scent and comfort level to your household.

We also offer new construction, air quality services, furnace services, and commercial services to the residents of St. Louis, MO, and the surrounding regions.

If you have more questions about why your AC unit smells, contact us today. Our technicians will be glad to help.