Funny Smell Coming from Your Air Conditioner? Here are 4 Likely Culprits

April 22, 2014

Does your air conditioner smell dirty or musty whenever it turns on? It can be difficult to locate the source of these funny smells if you don’t know where to look. 
 
In our experience, there are 4 common culprits of smelly air conditioners. Here they are!

Air filter

One of the most common causes of dirty or dusty smells in air conditioners is a dirty air filter. If your air conditioner smells funny and it’s been awhile since you changed the filter, do that first. 

 
Dirty filters do more than just cause unpleasant smells. They also make your air conditioner work harder, decreasing its lifespan and increasing your energy bills. 
 
So change it now.

Air conditioning coils

Many homeowners report a moldy smell coming from their air conditioner when they turn it on. Usually, this is coming from your air conditioning coils. The coils inside your A/C attract condensation, creating a moist environment where mold, mildew and other contaminants can thrive.
 
To get rid of the smell, consider getting a tune-up from a qualified air conditioning specialist who will clean the coils. Also, consider installing UV lights around your coils to prevent mold and bacteria from growing there. 

Drain pan

Your air conditioner removes humidity from the air as it cools. This moisture goes into a drain pan where it is then drained outside your home. However, if this drain gets clogged, water can back up. This backup not only causes mold growth and bad smells, but it can also lead to a much larger problem—a collapsed ceiling and water damage in your home.

Air ducts

Were none of the above the source of the smell? You may want to have an air conditioning professional inspect your air ducts. 

 
We’ve seen multiple things in ducts that can cause nasty smells including:

  • Large amounts of dirt and dust
  • Mold and mildew growth
  • Pest infestation

 
In these cases, consider a duct cleaning.