5 Air Conditioner Smells Explained – Dial One Sonshine

Your home’s central air conditioning should operate with a relatively low amount of noise and without any strange smells. If your AC system starts to produce unpleasant odors, unfortunately, this means that the system is either dirty or malfunctioning in one way or another. Here’s a quick rundown of the most common smells that come from HVAC systems, as well as the likely causes behind them.


Mold or Mildew

The unmistakable aroma of wet, neglected laundry is arguably the most prevalent odor you’ll see in any home with a modern HVAC system. This stinky situation is the result of excess moisture causing mold or mildew growth. These are some of the most common areas for this issue:

  • Air Filter: If enough moisture gets trapped in your HVAC system’s air filter, it can allow mold to start growing amongst the particles trapped there.
  • Ductwork: Your air ducts collect dust and other airborne particles over time. Damp, dirty air ducts can become the ideal breeding environment for mold and mildew.
  • Evaporator Coil and Drain Pan: Your AC’s evaporator coil creates condensation during the cooling process. That moisture drips down into the condensate drain pan, where it’s supposed to drain outside. If the coil and the drain pan are dirty, mold spores will have the food and temperature they require to grow in these locations.

Mold and mildew growth in your HVAC system can compromise your indoor air quality and cause you to experience symptoms like headaches and allergic reactions. To prevent these growths from occurring or to get rid of existing growths, it’s essential to invest in yearly maintenance for your air conditioning system. If mold or mildew growth is in your ductwork, you will need professional duct cleaning services to remove it.

Rotten Eggs

A sulfuric odor coming from vents is another typical AC smell you might encounter. Frequently, a dead animal in the ducts is the source of the problem. Having your ducts cleaned by an expert will save you the trouble of fishing out the smell’s source yourself, and while they’re at it, they can also clean the dust or mold that might be forming inside the ductwork.

A gas leak in your heating equipment can also cause a rotten egg smell. This is a serious issue that should be addressed by a professional immediately.

Burnt Rubber or Plastic

Generally speaking, the smell of torched synthetic materials is the result of electrical problems. More often than not, a clogged air filter will force fans and compressors to work at maximum capacity. The result is equipment failure and burning smells. This is just one of the reasons why it’s critical to check on your HVAC system’s air filter frequently to make sure that it isn’t clogged with dust.

Raw Sewage

This one is a bit of a no-brainer for those who know how modern residential plumbing works. Often, if a sewer line breaks close to AC ducts, it will cause the interior air to reek. You might also smell sewage if something is blocking a vent pipe in your drain-waste-vent system. If this is the case, have a plumber check for pipe ruptures or other plumbing issues.

Spent Fireworks

The smell of bottle rockets coming from the heart of your HVAC system is a strong indication that an electrical problem is in the works. This odor is usually the result of a short circuit somewhere within a circuit board. Bad fan motors can also smell like gunpowder under the right circumstances. When the fireworks odor crops up, don’t wait to call a licensed and insured HVAC contractor.

Nip Your Orange County AC Issues in the Bud Today!

If your HVAC system has started smelling strange, postponing the issue could lead to bigger problems down the road. Our experts at Dial One Sonshine are well equipped to track down the sources of AC odors of all kinds, no matter the cause: (714) 613-1016.

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