3 Possible Reasons Your AC Is Blowing Out Smelly Air

28 July 2015
 Categories: , Blog


Air conditioners are meant to improve the quality of your indoor life during the hottest months of the year. But sometimes problems inside the unit can make your indoor life smellier than normal. Musty or sour smells coming from the air conditioner can make you miserable even if the air conditioner is still producing cold air.

Here are a couple of the potential causes of stinky air coming out of your air conditioner. Call an HVAC installation and repair company for professional assistance if your do-it-yourself attempts aren't working.

Dirty Filter or Coils

A clogged air filter is one of the most common causes of both smelly air and lowered air conditioner efficiency. Dirt and airborne mold in the air gets stuck to the filter when the air is sucked into the unit for cooling. That dirt and mold can fester and cause the air passing through the filter to take on a musty or sour smell.

Changing or cleaning the filter is an important maintenance step. Consult your owner's manual to find out where the filter is located, how often it should be changed or cleaned, and the type of filter you need to purchase for replacement.

While you consult the manual, also look to see the location of your evaporator coils. The coils are inside the air handler portion of the unit that is located inside your home. Evaporator coils are where liquid refrigerant is transformed back into a gas, which causes the coils to become cold. A blower fan then passes warm air across the coils for cooling.

Dirty or grimy coils can add an unwanted scent to the air as its being cooled. You can clean the coils using a no-rinse cleaner according to package directions. Make sure all power is off to the unit before using the cleaner.

Condensate Drain Issue

If the air filter and coils seem clean, there might be an issue with the condensate drain, which is located in the air handler.

The refrigerant phase conversion in the evaporator coils causes condensation to form. That condensation drips to the bottom of the air handler where it is evacuated through either a direct drain pipe or a condensate pump, which sends it down a drain pipe. If there's a problem with that condensate pump or the drain pipe, stagnant water can form and create a musky or rotten smell.

You can try to unclog the drain yourself using a plunger, but it's best to leave any drain or condensate pump issues to a trained HVAC installation technician.