What’s That Weird Smell? Air Conditioner Smells and What They Mean

Are any of these air conditioner smells harmful? Does it mean that the air conditioner needs to be repaired or replaced?

If your AC smells bad, allow us to clear the air, so to speak. Read on for some common reasons your AC may stink, and how to get rid of a bad smell from your air conditioner.

How do I know if the bad smell is coming from my AC?

Of course, if you’re smelling an uncommon odor only when the air conditioner is on and running — especially one that gets stronger the closer you get to the vents — it’s obvious the bad smell is coming from the AC. But what about when you smell a familiar smell, such as a dirty diaper or cigarette smoke, but you can’t seem to pinpoint where it’s coming from? Your air conditioner may be the perpetrator in that case, too.

When the AC is turned on, other smell sources may be sucked into the air, causing you to smell the diaper pail that’s in the nursery upstairs while you’re down in the basement, for example. Likewise, if you, a friend, a family member or a former tenant smoked inside the home, the fumes could have been pulled into the evaporator coil, causing the cigarette smell to permeate throughout the house every time you turn the unit on.

Why does my air conditioner smell? Seven possible reasons.

There are plenty of possible culprits when your AC smells bad. Below are seven common smells and possible reasons why your AC stinks. 

1. Musty/Dirty Socks: Dust and moisture sticking on the AC evaporator coil and filter
2. Mold/Mildew: Clogged condensate drain line (i.e., water buildup), air conditioner too big for your home (i.e., running quick-cooling cycles and not adequately dehumidifying your home’s air), general moisture buildup
3. Rotten Egg: Pest problem or dead animal in the ductwork or attic, natural gas leak near the ductwork

Safety Tip: If you suspect a gas leak in your home, open the windows, get out of the house immediately and call the gas company. It could be a life-threatening situation.

4. Burning: Electrical/mechanical problem with the fan or compressor
5. Sewage: Backed up sewer line or ruptured vent pipe near the ductwork
6. Gun Powder: Shorted-out circuit board or fan motor
7. Exhaust: Leaking engine fluids

How do I get rid of bad smells from my air conditioner?

Luckily, most air conditioner smells occur because of a dirty or clogged air filter, and all you have to do is clean or replace the filter. If that doesn’t solve it, here are a few more steps to keep bad smells from your AC at bay.

• Ensure your condensate line is clean and free of debris. If you’re smelling an odor that can be found somewhere in your house, it should go away when the source of the smell is removed.
  
  
• If you’ve cleaned or replaced the filter, cleaned your condensate line and eliminated any obvious odor sources, but you’re still smelling the bad smell, you’ll need to call in the professionals. 

When your AC smells bad and you can’t figure out why, there will be times when DIY solutions aren’t enough. In particular, it’s especially important to call in the professionals if you suspect any leaks or electrical/mechanical issues with your unit.

Don’t Worry, Be Warranty

Aside from performing routine maintenance on your air conditioner unit, the best way to protect your home—and your budget—from unforeseen AC issues is to get a home warranty plan from American Home Shield®. Our ShieldPlatinum also includes one, free HVAC tune-up per contract term. We’re here to help you maintain your air conditioner and reduce costs for covered repairs.

Bad smell from your AC got you thinking you might be in need of an HVAC overhaul? Our New HVAC Program allows our members to leverage our national buying power to save thousands* off national retail pricing on a new HVAC system. Plus, when you get a new HVAC, you can breathe easier knowing it’s running more efficiently.

AHS assumes no responsibility, and specifically disclaims all liability, for your use of any and all information contained herein.