When the weather starts to warm up again, your AC will help the home stay cool and comfortable. However, if you start to notice an unpleasant smell coming from the device, you might contact an air conditioning company to determine what’s wrong with the system. Here are five strange AC odors and what they might mean.

What Is Making Your AC Smell?

1. Rotten Eggs

If the smell of rotten eggs isn’t coming from the fridge, you should treat it as a health hazard, as it can indicate a natural gas leak. The substance is odorless, but utility companies add a putrid smell to alert homeowners of the danger. If it seems to be coming from the AC, the gas has made its way into the ductwork. Turn off your gas supply, open all windows, evacuate the house, and call the fire department or gas company.

2. Mold or Mildew

A musty, stale smell is a common odor complaint that air conditioning companies hear. If you smell mold or mildew, chances are, that’s what is growing in your system. It can develop due to clogged condensate drain lines, dirty evaporator coils or air filters, or excess duct moisture. You can easily replace an air filter on your own, and to prevent the issue in the future, change this part every one to three months. However, the other issues will require the services of an HVAC company.

3. Chemicals

air conditioning company

A sweet, chemical aroma similar to paint thinner or formaldehyde can result from a refrigerant leak. Substances like Freon® cool the air in your home, but they can escape from a damaged line. Not only will this affect the device’s efficiency, but it could also pose a hazard to your health when inhaled. An air conditioning company can safely repair the issue and refill or recharge your system.

4. Burning Plastic or Gunpowder

When your AC releases a burnt plastic or gunpowder odor, there are a few possible causes. If it is the first time you turned on the device since last fall, the dust that settled on the unit over the past few months might be burning off. This is generally harmless and shouldn’t last long. If the odor persists, you may be dealing with an electrical issue. Failing components should only be handled by a professional.


If your AC system gives off strange smells, contact the experts at Ecology Air Innovations in Elverta, CA, for a thorough inspection and diagnosis. Serving homeowners throughout the Greater Sacramento area, this heating and air conditioning company offers reliable HVAC repair, maintenance, installation, and replacement services. They’ll work with any brand, make, and model to ensure your HVAC system provides continuous comfort year-round. Visit their website for more information about AC repairs, and call (916) 640-9464 to request service.