5 Reasons the Air from your AC System Smells Dank and Mildewy

Does the air coming from your air conditioning system smell dank, mildewy or just plain stinky? If the answer is yes, then you may want to contact a HVAC professional to determine the cause and provide a solution for this unpleasant issue.

In the meantime, here are 5 potential reasons why the air from your AC system may smell bad

Too Much Moisture in Your Air Ducts/Vents

The accumulation of small amounts of water inside your home’s air ducts and vents may be the result of a few possibilities…a high level of humidity or an undetected water leak. This is usually evidenced by a dank or mildew smell in the air when your AC unit is running, which in turn may mean that there could be a growing mold issue within your ducts and vents. Why might this be bad? Exposure to mold exposure may be harmful because it can lead to serious upper respiratory health problems.

Your Evaporator Coils are Frozen

Your AC system uses a refrigerant to absorb heat and moisture from the air within your home, then cool it and send it back inside your home. This process of heat exchange occurs at the evaporator coils.

When the warm air passes over these refrigerant filled evaporator coils, the coils will absorb some heat to prevent freezing. However, if not enough warm air passes over the evaporator coils, moisture from the air will be deposited onto the coils, leading to the accumulation of ice.  Some common reasons for frozen evaporator coils include dirty/clogged AC filters, a refrigerant leak or blocked or closed return vents.

Overflowing Drain Pan

Your AC system has a drain pan (typically in the attic) that is designed to capture the moisture that is removed from the air within your home. Over time, the drain pan can gather mold which may be why you smell dank or mildewy air.

Clogged Condensate Line

Your AC system has a small plastic pipe (a condensate line) that moves water from the drain pan to the exterior of your home. This can result in the growth of mold, mildew and sludge build-up that can cause the small drain pipe to become obstructed. Once that happens, you may begin to smell an unpleasant odor.

Incorrect AC Unit Size

Sometimes, just having the incorrect/improper size AC unit can cause odor issues in your home. Why? In order for your AC system to operate efficiently and correctly, it must not be too large, or too small. In fact, when your AC system is oversized (too big for your home), air throughout your home gets cycled too fast, which results in air that is not properly dehumidified or the presence of excess moisture.  This in turn can lead to a damp/mildew smell in the air within your home.

What Should I do if the Air in my Home Smells Stale or Damp?

When you notice the air in your home smelling stale, damp or otherwise unpleasant, we recommend you contact the HVAC experts at Eagle Air Heating and Cooling today at 480-748-1781.



Categories : HVAC Systems