Air Conditioner Smells Bad? Here’s Why and How to Fix It

On a hot summer day, we all just want cold air circulating in our room; however, how can you enjoy the cold air if your aircon smells bad? Well, simple answer, you can’t. This is why you should immediately know how to fix your air conditioner if it smells bad.

Not only for your comfort but if your air conditioner smells bad, there could be a lot of underlying issues. Different kind of smells indicates different kind of damage.

Air Conditioner Smell Bad: Why and How to Fix It

The following are the possible reasons why your air conditioner emits different types of bad smells.

Smell Like Feet

If your air conditioner smells like feet, there is one main possible reason, a dirty air conditioning unit. This kind of smell usually comes from water that does not drain properly. When the water just sits within the unit, it will start to smell bad.

How to Fix it:

This is luckily going to be an easy fix. This is just a sign that your air conditioner is too overdue for regular cleaning. We suggest that you call up a professional cleaning service, but if you are trying to save a few bucks, you can also clean your air conditioner on your own, make sure to be careful.

Smells Like Exhaust Fumes

This might be concerning for some as where could a smell like exhaust fume come from in an electricity-powered air conditioner? Your air conditioner has fluids in the engine that have a tendency to leak out.

How to Fix it:

There is no DIY way to fix this, as this could be engine fluids leaking; hence the best move for this is to contact a professional service to repair this leak.

Smells Like Gun Powder

What?! An air conditioning unit can smell like gun powder? Yes! It is possible; it is not dangerous either. This simply means that the fan motor of your air conditioning unit is short-circuited. An overheating motor results in a burning odour.

How to Fix This

To avoid further damages and risks, the best way to combat this is by contacting an HVAC company contractor.

Smell Like Skunk’s Spray

More often than not, a skunk’s spray smell is an indicator of a gas leak. It’s possible that methyl mercaptan, a gas that has a strong skunk-like odour, is leaking into your ducting and generating this odour in your house. This is a dangerous smell and can put those who might inhale the gas in danger.

How to Fix This

Air conditioners leaking gas is alarming damage; hence, immediately evacuate your home and contact a heating and cooling company ASAP; if you can, you may also contact the fire department, as leaking gas needs thorough checking.

Smells Like Rotten Eggs

The rotten egg smell coming from your air conditioning system is a sign of a dead animal. During the winter, rats and birds might find sanctuary in your air duct; they would usually get trapped, die, and start to rot. So if your AC stinks like rotten eggs, most likely, there are animal remains inside.

How to Fix This

This is another situation in which having a professional cleaning is the best option in order to ensure that there is no debris or small bits left to persist the bad smell.

Smells Like Mildew

An air conditioner smell that smells like mildew is a common occurrence. This is an indication that mildew is already starting to form close to your AC system. This is expected as AC units do have a lot of moisture. However, this moisture is an open space for moulds to develop, resulting in a smelly air conditioner. Another reason for this could be dirty filters or even dirty evaporator coils and condensate lines not performing in their optimum state, resulting in moisture build-up

How to Fix This

This is another situation when the bad ac smells indicate a regular overdue cleaning. To fix this, make sure to give your air conditioner a deep cleaning. Better yet, get it professionally cleaned.

Smells Like Cigarette Smoke

Air conditioners take in air from the outside, so if someone was smoking recently close to the outdoor parts of your ac unit, chances are, your ac unit will circulate a stale cigarette smoke kind of smell.

How to Fix This

This is an easy fix. The first thing you should do is to change the air filter. Then clean up your ac system. This is because even if your air filter no longer has a bad smell, the cigarette smell is lingering in the evaporator coil and air ducts.

More on how to deal with smelly AC


There you have it! Those are the most common unpleasant odour your air conditioner emits and the common reasons why they emit such smells. Of course, after knowing the whys, it is good to know how to fix such. If you are still unsure, you can always contact an HVAC contractor for help!

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