Whether it is the first time each season, or a daily occurence, your AC should never emit a musty odor! If you associate the click of your HVAC system turning on with a damp and earthy smell….then it is time to assess your system!
High humidity levels or a drainage leak could be causing excess moisture in your ducts and vents. This moisture building up where it shouldnt be can lead to mold and mildew growth. Exposure to mold can cause upper respiratory health complications, so if this scent is lingering in your space a duct cleaning service is definitely in order.
Another culprit could be a frozen evaporator coil. Air conditioning units take warm indoor air, remove the humidity, cool it on the coil, then cycle it back indoors. If your filter is dirty, dirt and debris block airflow through the filters which causes water drops to collect on the evaporator coil. These droplets then freeze onto the coil itself.
When not caught on the evaporator coil, moisture and droplets fall into the drain and drip pan. If this pan has worn over time it can accumulate mold, which can also be smelled when the unit is in operation.
Near the outdoor portion of your AC, is a line running from the drip pan to your landscaping. This is to drain the water from your drip pan, which makes it another prime option for housing mold. This line should be removed from its attachment once a month and cleaned with vinegar to remove debris and mold.
Avoiding mold in your equipment keeps your HVAC running it’s longest, but also keeps your family safe and secure.