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Why Does My Air Conditioning Unit Smell Bad?

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The biggest worry for homeowners come late spring or early summer is that their air conditioners won't turn on or blow out cold air. Like any home device, air conditioners can break or develop problems over the winter, leaving behind costly repairs. When your A/C turns on and blows out cold air, you know you’ve avoided the big problems, at least this time around.

But what if your air conditioner has an odor?

Air coming from your registers should be odorless, so if you’re smelling something, it indicates a problem somewhere. Your best defense is to smell the air coming through the vents to determine the original source.

Musty Smell

This is the most common stench since the condensation from the A/C and the dust that circulates through the system can be a prime breeding ground for mold and mildew. If you suspect that mold is forming in your system, it’s time to do a deep clean. Replace the filter and clean the inside of the unit, the front grille, coils and drip pan. You can also purchase a scented filter to improve the odor.

Rotten Smell

If there is a break in your A/C ducts under the home, a sick or injured animal may have crawled into the ducts looking for safety. Small animals like mice may also do this during the winter months to seek warmth. If the animal died in your ducts, it will create a rotten stench throughout the home. In this case, you will need the air ducts professionally cleaned.

Burning Smell

Nothing is worse than smelling burning in the home and not know where it’s coming from. A burning smell may indicate an electrical problem with your air conditioning unit, such as an overheating blower motor. What happens is that the plastic insulation that encompasses the wires heats up and causes this smell. There may also be plastic objects that are stuck in the ductwork and melting, or the air filter may be so dirty, the system has overheated.

Sewer Smell

If you smell rotten eggs, you may be in for double trouble. First, there may be backed up sewage from a ruptured line near your air duct system. Second, when the methane gases leak into the system, you smell the rotten egg odor throughout the home. Since neither of these issues are healthy, you will need the assistance of both a plumber and HVAC company.

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