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Common Problems

Air Conditioner Smells: 8 Reasons Why Your AC Smells Bad

What's in the article?

AC Smells Bad: Common Reasons and Solutions 

What to do Next?

Aircon Smell Be Gone

Cooling your home with your air conditioning, and suddenly smelling rotten eggs, cigarettes, or other weird air conditioner smells? Your AC unit might be the culprit. Foul smells coming from your air conditioner is not only a pain to endure, it may also indicate a serious problem with your AC components. 

AC Smells Bad: Common Reasons and Solutions 

Common reasons why your AC smells may be as simple as a dirty unit, smoke from outdoors, or foul smells in the air that go through your cooling system. With external causes, removing the source of the smell can fix the issue instantly.


Alternatively, a weird smell coming from AC systems can also indicate internal problems, like your unit overheating or an external cause made its way into your unit and is circulating foul odors around your home. Whatever the reason, our list will present the common causes and solutions for why your air conditioner stinks. 

Air Conditioner Smells Like Car Exhaust

Exhaust of car emitting smoke
The smell of car exhaust can mean fluid is leaking out of the AC unit.


The smell of car exhaust can throw off the homeowner from suspecting their AC unit since air conditioners typically run on electricity and not gas. However, fluids in the engine and other motorized parts of your aircon can release fumes similar to a car exhaust.


The fluids can leak out, which is what causes the car exhaust smell to come from your AC unit. Unplug your cooling system and have a professional technician find and fix the leak to solve the problem.

Air Conditioner Smells Like Something’s on Fire

Man holding nose and grimacing
Anything that smells like it's burning probably is.


If you find yourself asking “Why does my air conditioner smell like something’s on fire?” then that is a pretty clear sign to immediately turn off your air conditioning unit. The smell of burnt rubber, burnt plastic, or any burning material is what it is - something is burning. 


A burnt air conditioner smell may mean that your AC motor is overheating, and its parts are burning. Turn off your air conditioning, unplug the unit from its power source, and contact your maintenance provider to fix or replace your unit. Do not continue to run your AC unit if you notice a burning smell.


That burnt smell is not just foul, it is a sign of danger as a component in your cooling system is on the fritz. If the air conditioner smell is coupled by smoke or flames and you cannot unplug the unit, have an electrical fire extinguisher ready, and call your local fire department. 

Air Conditioner Smells Like Rotten Eggs

One whole brown egg beside cracked brown egg that has exposed yolk
Sulfur can smell like rotten eggs.


The foul smell of rotten eggs is mainly due to the sulfurous gas released in the decaying process. This gas is also released when small critters, such as rodents and birds, decompose. If you smell rotten eggs wafting around your ventilation systems, it is often due to an animal which has made its way into your cooling system, and has died. 


Though a macabre task, just remove the carcass and dispose properly. Allow the smell to dissipate and clean your unit, focusing on where the carcass was found. Your AC should be smelling much better afterwards.

Air Conditioner Smells Like Skunk Odor

Skunk on white background
Gas leaks can sometimes smell like skunks.


Check for a gas leak because that skunk odor might be gas making its way into your ventilation system. Methyl Mercaptan is a colorless and flammable gas that has the distinctive odor similar to skunk spray, sulfur, or rotten cabbage. 


Turn off all electrical devices, extinguish stove flames and cigarettes, and immediately call a specialist if you suspect the gas leak is the source of the smell. Turn off your main gas supply if possible.

Air Conditioner Smells Moldy or Musty

White mold on concrete
Mold and mildew are the leading causes for musty smells.


The smell of mold emitting from your air conditioner is exactly what it is: mold! Your air conditioner smells musty due to water accumulating in the drain pan or drip pipes, allowing mold and mildew colonies to thrive. Mold can also grow within dirty air filters due to humidity and moisture.


Have your unit inspected and professionally cleaned. Leaks leading to water accumulation in the drain pan should be fixed in an AC repair center. Make sure to clean your air filters regularly, and allow them to dry completely before placing them back in the unit.

Air Conditioner Smells Like Cigarettes

man in suit holding a cigar
Smoking indoors can circulate the smell around the room.


Has someone smoked cigarettes around the house recently? Your air conditioner may be dispersing the smell of cigarettes from within your home, or from outside. Avoid smoking indoors, and smoke only in well-ventilated areas. Avoid smoking near the outside unit, which may bring the smell of cigarettes indoors.

Air Conditioner Smells Like Gunpowder

woman holding nose and grimacing
Gunpowder smells can mean electrical issues.


For a gunpowder-like odor, a frizzled electrical wiring is the prime suspect. Fried fan motors or circuit boards can release a smell similar to gunpowder. Turn off your unit, and have a professional technician inspect it for any burnt off parts. 


You may need to look into replacing damaged parts, or replacing your unit altogether in this case.

Air Conditioner Smells Like Foot Odor

man with glasses holding up sock in one hand, holding nose in other hand
AC units emitting foot smells may indicate stagnant water around the unit.


Stagnant water in the drip line, dirty compressor coils, and clogged drain pans can emanate a stinky feet smell or the odor of dirty socks. Have your unit cleaned, and check for leaks in the drip line that may be causing water to drip into your unit.

What to do Next?

After solving the problem, your next best step is to prevent it from happening again. Foul AC smells pose more than just a nuisance, they can be harmful to your health. 


For instance, the musty smell of mold means you’ve been inhaling mold spores that can cause allergies. The gunpowder smell from burnt metals in your unit can pose potential dangers to your respiratory system. The skunk smell indicates a gas leak, which needs to be dealt with as soon as possible. 

Clean Your AC Unit

Clean the exterior of your air conditioner at least once a month. Your outdoor unit should also be cleaned regularly, and cleared of any dirt or debris that may block the vents. Air filters should be cleaned with soap and water every two weeks to maintain its functionality at the fullest. 


Simple home cleaning can save your thousands of dollars in repair and maintenance costs, and lengthens the lifespan of your unit. 

Schedule Routine AC Cleaning Services

For deep, professional cleaning, schedule a general maintenance service with a trusted provider every 6 months to keep your AC unit in tip top shape. Professional cleaning services get into the nooks and crannies that home cleaning can’t reach. 

Book a Chemical Wash and Overhaul

Every now and then, an air conditioning unit would benefit from a chemical wash and chemical overhaul to keep it running smoothly. A chemical wash cleans and sterilizes aircon components so they can work at full capacity. 

Aircon Smell Be Gone

Whatever service you choose, Luce Air Conditioner can help you thoroughly clean your AC unit, and repair any issues. With over decades of experience, we’ve seen and smelled it all. Book an appointment with us, or check out our blog for more air conditioning tips and tricks.

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Staff Writer

Staff Writer

This article is written by our passionate staff writers who seek to share our knowledge from our business

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