Why Does Your Air Conditioning Smell Bad?

When cool air comes out of your vents, you want that air to smell fresh and clean. So, what if it's stinky? Should you be alarmed if your air conditioning starts to smell bad? That depends on the nature of the odors you're noticing. Here's a look at common AC odors, what causes them, and how you (or an HVAC contractor) can address them.

Musty Smells  

Does your air conditioner air smell like a humid basement or mold? Chances are, there is mold growing somewhere either in the air conditioner.

One common place where mold grows is in the condensate drain tube, which carries condensed water away from the AC unit. This is a clear tube, and you can usually find it quite easily. If you see lots of mold inside of it, you can try pouring some bleach into the condensate drain. The bleach will travel through the pipe and kill the mold. If this does not keep the mold under control, you can instead have your HVAC contractor replace the condensate line. It's an inexpensive part and this is an easy repair for them to make.

Car Exhaust

If the conditioned air smells like car exhaust or like chemicals in general, you may have a refrigerant leak. Some of the refrigerants used in air conditioners have a pretty strong, exhaust-like odor. You can check for a refrigerant leak by putting white paper under your AC unit. If you notice drips of colored fluid on the paper, you have a leak. 

An HVAC contractor can usually fix a refrigerant leak and then top up your AC unit's refrigerant levels. However, if your AC unit is older, this may not be worth doing. Replacing your AC unit may be more affordable in the long run.

Feces or Death

It can be pretty alarming to have your air conditioner air smell like feces or a dead animal. The good news is that this rarely points to an issue with the AC itself. Instead, it's more likely an animal found its way into your ducts and either defecated or passed away. An HVAC contractor can send a camera into your ducts, locate the culprit, and then remove it and sanitize your ductwork.

Don't ignore strange odors coming from your air conditioning. They are not usually caused by anything too serious, but they should be addressed by a trained HVAC contractor to prevent future issues.

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