Why Does My AC Smell? A San Antonio Tech Explains

Air Filter

Smelling strong or unpleasant odors coming from your AC?

That’s usually an indication there’s an issue with your AC that a tech will need to fix.

If your AC smells like…

  • Dirty socks (musty smell)
  • Rotten eggs
  • Burning or gunpowder
  • Chemicals

…read on. We’ll go into more detail about each of these smells and what causes them.
Want a pro to get rid of that nasty smell? Hire a San Antonio pro to repair your AC.

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… it most likely means you have a mold/mildew issue.

The source of a musty, mold smell usually comes from 1 of these 3 AC problems:

  1. Clogged condensate line
  2. Dirty evaporator coil
  3. Leaks in the air ducts

Let’s look at each of these issues in more detail.

As your AC cools your home, it removes moisture from your home’s warm, humid air. That moisture exits your home via a condensate drain line.

Occasionally, the condensate drain line will become clogged with dirt or debris. When this happens, water backs up and collects in the drain pan.

If the water sits in the drain pan for a long time, mold can start to grow, especially since the drain pan located in a warm, dark place.

In addition to a moldy smell, you’ll know you have a clogged condensate line if you notice any of the following problems:

  • Pools of water around your indoor unit.
  • Your AC runs only for a short time then shuts down (when the water level gets too high, it triggers an emergency shut-off switch.)

Solution: Hire a professional to clear the condensate line of any debris that could be causing a clog.

The evaporator coil is the part of your AC system that actually cools your home (by removing heat from your home’s warm air).

As your evaporator coil removes heat from warm, humid air, it also removes moisture from the air at the same time. If the evaporator coil is dirty, then that moisture will mix with the dirt and create mold. This could explain the musty, dirty-sock smell.

Solution: Hire a professional to clean the evaporator coil. The coil can easily become damaged if not handled carefully, resulting in an expensive repair. That’s why we recommend leaving the cleaning to a professional.

Your ducts are usually located in unconditioned spaces (like the attic), where mold spores and dust mites thrive.

If your ducts have leaks, those mold spores and dust mites can enter your ductwork and mold can grow inside the ducts, which can result in a dirty-sock smell.

Solution: You’ll need to hire a professional do 2 things:

  1. Clean your ducts
  2. Seal your ducts (to prevent further mold growth)

Note: We don’t offer duct cleaning, but we do offer duct sealing.

… you most likely have 1 of 2 problems:

  1. A decaying animal in your ducts: It’s sad and gross, but no homeowner is immune to this issue. Sometimes little critters find their way into your attic, get stuck and die there. You’ll need to have a professional inspect your ductwork and remove any decaying animals.
  2. A gas leak in your furnace: Central air conditioners don’t use natural gas as a fuel source, but a furnace does. Since your furnace shares the same space as your AC, if there’s a gas leak, you’ll definitely smell it around your AC system. You’ll need to contact a professional to find and fix the gas leak.

Solution: If you notice a rotten egg smell, contact a professional for assistance.

…then your AC system probably has an electrical problem.

Your AC system is made up of circuit boards, motors and electrical wiring. If one of these components is overheating or malfunctioning, you might notice a bad smell in your home.

Solution: Contact a professional to replace or repair any broken electrical components in your AC system.

…then you most likely have a refrigerant leak.

Refrigerant is the liquid/gas that removes heat from your home. When exposed, refrigerant has a sweet, chloroform odor, which could be the chemical scent you’re smelling.

If you have a refrigerant leak, you’ll also notice signs like:

  • Higher-than-normal energy bills
  • Warm air coming from your AC vents
  • Ice on refrigerant lines
  • A hissing or bubbling sound near your AC

Solution: Contact a professional to inspect your system for a refrigerant leak. Since refrigerant can cause harm to humans, it’s best to let a technician handle the substance instead of attempting to fix the leaks yourself.

Contact us today


We offer quick, same-day repairs and 24/7 emergency service. No matter the issue, we can help get your AC smelling normal again!

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