Why Does My Air Conditioner Smell Bad?

What if, on a sweaty hot summer day, you turn on your AC only to find out that it smells bad. Has it ever happened to you? If it has, you’re not alone. But will the bad smell vanish after some time, AC? Is bad smell from air conditioner some kind of indicator?

Well, if you have any of the above concerns, this is the right place. Here we’ll talk about why your AC smells bad and what you can do to fix it. You must know that a different type of smell indicates different problems. If you’re curious to know what’s exactly wrong with your AC, read on.

Why Does My Air Conditioner Smells Bad & How to Fix it?

Well, there can be many reasons behind a bad-smelling AC. But all it depends on is what your AC smells like.

1. Burning Smell: 

If you can sense a burning smell coming from your AC, there’s a chance of a short circuit. An air conditioner is a large unit made from thousands of small components working together. Even a single faulty component can disrupt the entire system.

What should you do?

So, if you feel there’s a burning smell, the first thing you should do is turn off the AC. You should call a technician or the fire department if the smell doesn’t vanish even after turning the AC on.

2. Cigarette Smell:

Cigarette smell is quite self-suggestive. If you or someone else in our home smokes, the chances are that the compressor unit picked smoke particles. The air was then filtered, but the scent particles remained, which caused the smell.

What Should you do?

However, this is a common problem, and you can handle this easily. You can change the filter, and the smell will vanish. Usually, it is suggested to replace the filter twice each year. But if you experience a cigarette smell, it is better to replace the filter at once.

3. The smell of Rotten eggs: 

If you don’t have any rotten eggs lying in your home and it still smells of rotten eggs, it’s probably a gas leak. Sometimes, the pipes carrying gases get loose or crack. And, this leads to leakage of gas. Manufacturers add this particular kind of smell to alert the users in case of a leak.

What should you do?

In such a case, you should take the matter more seriously. If you’ve been experiencing it for quite a long time, you should call a technician once and for all. It’s because this gas is hazardous for health. And prolonged exposure to this can even lead to death. You can open the windows and let the fresh air in. Of course, you can call the expert thereafter.

4. Exhaust fumes or chemical smell:

Exhaust fumes usually are a result of leakage of fluids from the AC unit. The exhaust fan within the AC unit fans the fumes within your room. It’s another health risk that must be taken care of. Also, the chemical odor could be a result of fluid leakage. There are a variety of fluids used in the AC, which help in delivering cool air.

What should you do?

Whatever the case, you must call for an immediate inspection. These issues pose a direct health risk and can deplete oxygen. So, calling an expert ASAP is what’s preferable in this case.

5. Musty smell:

Musty smell s another common type of smell you may find coming from your AC. A musty smell arises from molds and mildew. Whenever you operate the Air conditioner, a common procedure of condensation takes place within the unit.

This creates a lot of moisture, which usually travels out through the drain pipes. In some cases, when the moisture isn’t able to escape, it results in molds. The moisture and the temperature within the unit become a perfect breeding point for mildew and other bacteria. And, this is what leads to a musty odor from the AC.

What should you do?

It is quite hard to diagnose mold and mildew. It’s because they grow slowly. And while they grow, you might become used to its smell. Only if a visitor comes and tells you or there’s an unnaturally high amount of smell you can diagnose this problem.

However, you should go for an immediate inspection. The expert will check your system for a possible leakage issue. And, if your AC is in warranty, you may get a free replacement or repair as well.

6. A generally bad smell:

Sometimes it’s generally bad. It neither smells of rotten eggs, cigarettes, or molds. It usually happens when the filter has accumulated too much dirt. If you haven’t replaced your AC’s filter for over a year, it’ll smell bad.

What should you do?

This is something you can handle at home. You can manually remove the filter and direct a jet of pressurized water through it. This will help you clean the filter and remove the unusual odor.

Can I Deal With Odor Related Problems at Home?

Well, this entirely depends on what kind of odor you experience. When cleaning or replacing a filter can make it right, you can do that on your own. Although it is not suggested to service or change the filter on your own but with general practice, you can.

And, when there’s something as complex as burning smell, a professional is the best choice to make. A professional can help you diagnose the problem and check for similar problems. After which you can enjoy the cool air for a long time.

Summary of common odor problems and solutions:

Odor TypeProblemSolution
Burning SmellShort CircuitCall a Technician/fire department
Cigarette SmellPossible cigarette smokeReplacing the air filter
Rotten Egg SmellPossible gas leakageCall a technician
Musty SmellMold or MildewCall a technician
Chemical or exhaust fumesLeakage of unit fluidsCall a technician
General Bad SmellUnknownCall an expert for inspection


Be it the smell of rotten eggs, exhaust fumes, or molds you need not panic. Although it shouldn’t be taken lightly, panicking is not a solution either. What you should do is find the root cause behind the smell. And, even if you’re unable to find the root cause, you can right away call for an expert.

He’ll inspect the entire AC unit and will present a reliable solution. The above information is based on the usual odor related scenarios. The real problem which you may be facing can be entirely different. However, if you find help from this piece of info, do share it with others in need. Also, please come back for more.