5 Toxic Smells Coming From Your AC Unit

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5 Toxic Smells Coming From Your AC Unit

Smells coming from your AC unit are never a good sign.

Your AC unit is one of the most used appliances in your household, and it can become inconvenient when it doesn’t work properly. We’ve talked about how to improve your air quality, as well as knowing when the air filter needs changing or the unit needs replacing, but what about when your unit begins to smell? 

Here’s a breakdown of the odors you should look out for, as they are potentially dangerous to you and your family:

Mouldy or Musty Smell

One of the most common AC unit odors is the smell of mold or mildew. When the air condition unit runs, condensation builds up inside, and if it doesn’t drain properly, the leak can escape in the ducts and create mold and mildew. Cleaning the build-up is easy, but fixing the issue requires a professional. Mold and mildew create poor air quality, resulting in inflamed respiratory issues, but overall it’s not terribly dangerous and the system can still be used while you wait for a technician.

Chemical Aroma

If your AC unit starts giving off a chemical smell, similar to paint thinner or bleach, you should immediately call an HVAC technician to check it out. Your AC unit requires certain fluids to function, but when a chemical odor is emitting from your AC unit, it could mean a system malfunction has occurred. This could mean a refrigerant leak or chemicals around the unit are causing fumes to circulate. None are good options and it’s best to have a professional repair the issue. 

Burning Odor

When your AC unit produces a burning odor, it could mean there is an electrical issue with the wiring. If you’ve just installed the AC unit and are noticing this smell, it could be dust coming off the unit and should dissipate when the fan kicks on a couple more times. If it persists, long-term exposure to these electrical fumes is not healthy or safe. A professional would need to repair the motor or the wiring of your unit.


If you start smelling gunpowder or something metallic in the air, it could be associated with the burning odor of an electrical component. Your unit is made of up metal parts and chemical fluids, and a fried circuit board or faulty fan motor could be equally as dangerous to you and your family. 

Rotten Eggs

If your AC unit has started to emit a rotten egg smell, it could be a natural gas leak in your system. Most utility systems add a gas leak feature to alert residents of a dangerous leak. Over time, high levels of exposure could result in a loss of consciousness and death. The gas itself is also extremely flammable and explosive, so if you notice this smell, act immediately. Open all your windows to your home, get out of the house, and then call the gas company.

When you smell something out of the ordinary with your unit, check the area for noises or excess water. Usually the smells coming from your unit are normal like mold or mildew, but rotten eggs or gas are very serious and you should immediately turn the AC unit off and call a technician.