Why Does the Air Conditioner Smell?


Many people often note that when they turn on their air conditioner, an unpleasant odor comes out along with the cool air. This odor may be temporary, dissipating within a few minutes of running the machine, or it may continue to smell the entire time you run it. There are several explanations for why an air conditioner may smell, and all of them are fairly easy to take care of yourself.

Five Reasons Why Your Air Conditioner May Smell

Air conditioners can to have an odor for a few different reasons. You may need to do a little investigating to determine what your particular cause is.

Dirty Filter

Your air conditioner filters the air to remove things like pollen or dust as it runs. Because the interior of your air conditioner is a fairly damp environment, this can cause spores or other things caught in your filter to multiply and grow, causing an unpleasant odor. Likewise, if something with an odor has been caught in the filter, this could cause the air passing through it to smell. Most air conditioning filters should be changed on a regular basis regardless of odor issues. if your air conditioner smells, your first step should be to change the filter and see if this eliminates the problem.

Stagnant Water

Air conditioners need to drain well to eliminate the excess water that forms by condensing the air. If your air conditioner isn’t draining, the excess water could back up and become stagnant over time when the unit isn’t running. This stagnant water can be a breeding ground for algae and mold, which in turn will cause an odor when the machine is running. To fix this, clean out the bottom of the unit, and make sure it drains properly to prevent it from happening again.

Mildew in the Cover

Air conditioning units are typically housed outdoors year round. This outdoor environment combined with the moisture they produce is the perfect breeding ground for mildew on the inside of the cover. Try unscrewing the cover and taking a look inside it. If you see mildew, clean it out with some white vinegar. This should eliminate the smell.

Algae on the Blower and Coil

The blower and coil area can also become clogged with algae and mildew because it is continuously damp when the unit is on. (It doesn’t always get the chance to dry out again once the unit is off.) This leads to algae and mildew growth that can get quite thick, particularly around the base. Take off the front cover and the filter to expose the coil and let the unit run while you spray it down inside with a mix of vinegar and water in equal parts. If the algae are particularly thick in places, you may need to scrub it down with an old toothbrush to get rid of it all. There is no need to rinse the vinegar off when you are done; when the vinegar dries it will remove the musty smell with it.

Dead Rodents Inside

While it’s not fun to think about, sometimes small rodents can get trapped inside your air conditioning unit. When this happens, and they can’t get out to find food, they die inside and their decaying corpses create a very strong, unpleasant smell. When this happens, you need to take off the cover and filter to expose the interior and remove the carcass. Spray down the interior with a water and vinegar mix to get rid of any lingering odors before putting the cover back on.

Keep Your Unit Running Well

Changing the filter and cleaning your air conditioner on a regular basis will help to prevent any unpleasant odors from forming. Perform regular maintenance on your unit, and help keep the air flowing freely without any accompanying odor.

Precision Air & Plumbing September 29, 2017


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