In Florida, the AC runs most of the year, so when it starts blowing a bad smell, you notice it everywhere. The type of smell tells you a lot about what’s going on. Here are the five most common ones.
1. Musty or Moldy Smell
Usually means: moisture in the AC system. A clogged condensate line, a wet drain pan, dirty coils, or mold growing in the air handler or ducts.
What to do: change the filter, check the drain pan for standing water, and look around the AC closet for stains or growth. See our guides on mold in air ducts and mold in your AC closet.
2. “Dirty Socks” Smell
Usually means: buildup on the evaporator coil. It’s common in humid climates and tends to be strongest when the system first starts up.
What to do: have an HVAC technician clean the coils and check the drainage.
3. Burning or Electrical Smell
Usually means: an overheating motor, wiring problem, or something stuck near a hot component. A faint dusty smell the first time a unit runs in a while can be normal, but a strong or ongoing burning smell is not.
What to do: turn the system off at the thermostat and breaker and call an HVAC technician. If you see smoke, get out and call 911.
4. Rotten Egg Smell
Could mean: a natural gas leak if your home has gas appliances. Gas companies add that smell on purpose.
What to do: treat it as an emergency. Don’t flip switches or use flames. Leave the house and call your gas company or 911 from outside.
5. Sewage Smell
Usually means: a dried-out drain trap near the AC, a plumbing vent problem, or a sewer line issue nearby, with the AC pulling the smell through the house.
What to do: run water in rarely used sinks and showers to refill the traps. If it continues, call a plumber.
When the Problem Is Fixed but the Smell Isn’t
Once the cause is repaired, odors can still hang around in the ducts, furniture, carpet, and closets. Since the AC moves air through every room, the whole house can keep smelling for weeks.
Our whole-home odor removal treatment treats the air throughout the entire home, including one AC system, to remove those lingering odors. You’ll be out of the home for about 8 hours. It’s an odor treatment, so we always make sure the cause, whether that’s moisture, mold, or a mechanical issue, has been handled first.
Get Help in South Florida
Musty smell and worried about moisture or mold? Request a free visual inspection with moisture readings and an infrared (thermal) camera. Cause fixed but the smell stays? Our Whole-Home Odor Removal Treatment is $997 and includes one AC system ($550 for each additional AC unit), and you can buy and schedule it online. Call 877-224-2532. We answer 24/7, and hablamos español.
About the author: James Rice-Peña is the owner of FL Cleanup and a Florida-licensed Mold Assessor (MRSA4035) and Mold Remediator (MRSR4158). He has worked in property restoration in South Florida since 2012, and FL Cleanup has earned 200+ five-star Google reviews.
