What's That Smell? What Different Air Conditioner Smells Mean

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What's That Smell? What Different Air Conditioner Smells Mean

It’s a hot summer day and you turn on your air conditioner to cool down. You’re met with a funny smell instead of fresh air. Maybe it’s nothing serious, but it could be.

Different smells mean different problems. Continue reading to learn about various air conditioner smells and how to get rid of them.

Cigarette Smoke

Any cigarette smoke that is inside or outside of the house will cause a buildup in your air conditioner filter over time. When you turn it on the smell of smoke will spread throughout your house.

Eliminate the odor by cleaning the filter, coils, and shell of the air conditioner. You may have to replace the filter if it’s too clogged.

Burnt Smell

If your HVAC unit smells like it’s burning, turn it off right away. There could be a problem with the compressor, capacitor, or fan that’s causing the unit to overheat. You’ll have to call a technician.

The stench could be from a filter that hasn’t been changed in a while. The restricted airflow puts a strain on the inner-workings of your air conditioner. Filters should be cleaned or replaced once a month.

A less intense odor that disappears after a few minutes is nothing to worry about. The dust that’s collected inside is burning away. This mostly happens when you turn on your unit after a long time.

Gun Powder

The smell of gun powder indicates an electrical short somewhere in your air conditioner. It could be the fan or circuit board. Turn off the unit and contact a technician.


A smell like fumes from a running car could mean refrigerant is leaking out somewhere. Leaks are caused by cracks or holes in the coils that circulate the liquid.

Too much of a leak and the unit will start overheating. Most air conditioners use Freon as a refrigerant, a poisonous chemical. Be sure to call a technician to fix the problem.

Dirty Feet

When the water in your air conditioner doesn’t drain properly it sits and begins to smell like feet. Have a technician thoroughly clean the unit. This will get rid of the odor and unclog the drain.


Improper drainage can also become a home for mold and mildew. The water is from dehumidified air. As the moisture collects, bacteria are more likely to grow.

Changing your air filter could solve the issue. If there’s still a smell, call a professional to clean the whole system.

Rank Garbage

The smell of nasty garbage means an animal may have crawled into your air conditioner for shelter during the winter. It’s more unpleasant than a hazard, so there won’t be any damage to the unit.

Have a technician remove the dead animal and clean the area it was in.

Rotten Eggs

A similar smell to bad garbage, but more dangerous. A rotten egg stench indicates a gas leak.

Your gas lines could be the problem instead of your HVAC unit. However, there may be a leak around your air ducts if the smell is coming from the AC vents.

Leave your house either way. Call your gas company and an HVAC professional.


This smell is from methane, a harmful gas, coming from a sewer line leak or back-up. Your AC will blow the gas into your home if the leak is near your air ducts.

Contact a plumber and HVAC technician immediately.

Air Conditioner Smells Can Be Dangerous

Knowing what air conditioner smells indicate is vital. Some gases and liquids that can leak out are harmful. Enough methane, Freon, or natural gas and it’s lethal.

If you notice a strange smell in your house, don’t hesitate to find out what the source is.

Feel free to contact us by email or call us at 303-945-4319.

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