AC odors

8 Odors You May Smell from Your AC and How to Remove Them

Air conditioners (ACs) are essential household appliances that provide a cool and comfortable indoor environment during hot and humid weather. Aside from removing warm air from the room and replacing it with cool and dry air, ACs also help improve indoor air quality by filtering out pollutants and allergens, making breathing easier for people with respiratory conditions. Moreover, ACs also help prevent heat-related illnesses such as heatstroke, heat exhaustion, and dehydration.

While ACs provide numerous benefits, they can sometimes emit unpleasant odors that can be bothersome and even hazardous to health. Various factors, such as mold, mildew, bacteria, and chemical emissions from the AC unit, can cause these odors. It is important to address these odors promptly as they can affect indoor air quality, causing respiratory problems, headaches, and other health issues. While it’s easy to try removing them, some odors are more resilient, making them hard to remove.

For this reason, we will discuss some of the most common smells your AC may emit and how you can remove them. These include:

#1 – Burning Scent

A burning smell from the AC unit indicates a potential electrical issue. It’s crucial to address this odor promptly to prevent further damage and potential fire hazards. Several factors, such as a faulty motor, wiring issues, or a clogged air filter, can cause the burning scent.

To remove the burning smell, turn off the AC unit and unplug it from the electrical outlet immediately. If the burning smell persists, contact a professional HVAC technician to inspect and repair the unit. To prevent burning smells from occurring, you must maintain your AC unit regularly. This includes replacing air filters every three months, cleaning the unit’s coils, and scheduling yearly maintenance checks with an HVAC technician.

#2 – Cigarette Smoke

If you smell cigarette smoke from your AC unit, there are a few possible causes. The most obvious is that someone has been smoking near the unit, and the smell is pulled into the air intake. Another possibility is a buildup of dust, dirt, and other contaminants in the air filter or ductwork, which can trap smoke particles and release them when the AC is running.

To eliminate the cigarette smoke smell, replace the air filter in your AC unit. This will help to trap any remaining smoke particles and prevent them from circulating through your home. You should also have your ductwork cleaned by a professional HVAC technician to remove any buildup of contaminants contributing to the problem.

#3 – Dirty Socks

If your AC unit emits a dirty sock smell, it is likely due to the buildup of bacteria and mold in the system. This can happen when moisture is trapped in the air conditioning unit, providing a breeding ground for these unwanted organisms.

To eliminate the dirty sock smell, clean or replace the air filter in your AC unit. You can have your ductwork cleaned by a professional HVAC technician to remove bacteria and mold buildup. In addition, you can take steps to prevent future buildup by ensuring proper ventilation and reducing humidity levels in your home. This can include using a dehumidifier, opening windows and doors to allow airflow, and ensuring proper drainage around your home’s foundation.

#4 – Exhaust Fumes

If you smell exhaust fumes from your AC unit, it could be a serious issue requiring immediate attention. This could indicate a leak in your AC unit’s refrigerant, which is toxic and can be dangerous if inhaled. If you suspect a refrigerant leak, immediately turn off your AC unit and contact a professional HVAC technician to inspect and repair the issue. Do not attempt to fix the problem yourself or continue using the AC unit until it has been repaired.

In addition to a refrigerant leak, exhaust fumes could be caused by a malfunctioning gas furnace burner or a ventilation system problem. Again, you must have a professional HVAC technician inspect and repair the issue to ensure your safety and the proper functioning of your AC unit.

#5 – Garbage

If you notice a foul odor from your AC unit, it could be due to garbage or other organic matter in or around the unit. This can attract insects and rodents, which can cause damage to the unit and pose a health hazard. To avoid this issue, regularly clean and maintain your AC unit and keep the surrounding area debris-free. If the odor persists, contact a professional HVAC technician to inspect and clean the unit.

#6 – Mold and Mildew Odors

Mold and mildew are bound to grow in damp and humid environments, which can happen in your AC unit if improperly maintained. These microorganisms can cause respiratory problems and other health issues. Signs of mold and mildew include a musty odor and visible black or green spots on the unit or surrounding areas. To prevent mold and mildew growth, regularly clean and replace filters, drain pans, and coils, and ensure proper ventilation.

#7 – Rotten Eggs

If you detect a rotten egg smell from your AC unit, this could signal a gas leak. Gas leaks are extremely hazardous and can cause explosions, fires, and carbon monoxide poisoning. Evacuate your home immediately and call your gas company or emergency services. Do not turn on electrical devices or use your phone until you are safely away from the area. Gas leaks require professional attention and should never be ignored.

#8 – Vehicle Coolant

If you notice a sweet, syrupy smell coming from your AC unit, it could be a sign of a coolant leak. Coolant is a toxic substance that can cause harm to humans and animals if ingested or inhaled. If you suspect a coolant leak, immediately turn off your AC unit and contact a professional to repair the leak and dispose of any contaminated materials properly. Do not attempt to handle or clean up the coolant yourself.


ACs are essential to modern living, providing comfort and relief from the heat. However, it’s important to remember that they require regular maintenance and care to function properly and safely, or else they can become a hazard to our health and safety. If you ever need professional assistance, don’t hesitate to contact a trusted HVAC technician for help.

AutumnAir provides top-quality services for air conditioner repair in Birmingham, AL. Our professional AC technicians will ensure your AC unit is fixed in top condition to serve its purpose efficiently. Call us today at (205) 800-3400 to schedule an appointment!

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