Aug 16

Where Are Those Air Conditioner Smells Coming From?

woman plugging nose due to smelly air conditioner

When you have an air-conditioned room, it’s definitely understandable that you’d want it to smell normal. Whenever you turn your air conditioner on, you shouldn’t notice any air conditioner smells that are unpleasant, strange, or offensive.

However, as much as we want to prevent this, there are certain moments when your air conditioner produces a certain stench. But whatever that smell is, it should be checked immediately because these odors are most likely signs of an air conditioner issue that needs to be taken care of.

In this article, we’re going to talk about the types of smells that air conditioners produce, what causes them, and what you can do to stop them.

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What Is Causing That Air Conditioner Smell?

There are tons of reasons why your cooling system may produce an odor. Some of the most common odors people complain about are:

  • Moldy smell
  • Cigarette Smoke
  • Burning Smell
  • Rotten Egg Smell
  • Gas

So, if you smell any of these in your home, read on and find out how you can solve them.

Air Conditioner Smells Like Mold

image of mold that was on air conditioner

The smell of mold is one of the most commonly reported scents that homeowners complain about.

As we all know, moisture combined with ambient temperatures can create an environment that enables mold, mildew, or fungus to grow. So, if your room smells like mold, then it’s highly likely that these microorganisms are present in your air conditioning unit.

This moldy smell can often be traced back to water that has accumulated in the drip lines, ducts, drain pans, or also dirty or clogged HVAC filters.

If you live in an area that experiences high temperatures and humidity, moisture can easily develop and accumulate in the air filters. So, if you haven’t used your AC unit in a while, the moldy smell will immediately fill your room by the time you turn that on.

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What’s the Solution?

To stop your air conditioner unit from releasing a moldy smell, it’s best to empty your drain pan regularly. This should ensure that moisture is properly removed.

However, if this does not get rid of the stale stench, it’s best to call an HVAC technician to get your central air conditioner, ducts, and lines inspected.

If the HVAC technician finds that water is accumulating in your air conditioner unit, then there may be leakage too. So, a whole unit inspection will help technicians see what causes the water to drain improperly.

Now, don’t just wait until a smell comes out of your air conditioner before you have it checked. It’s important to note that annual air conditioner tune-ups are important to prevent these issues from happening in the first place.


Air Conditioner Smells Like Cigarette Smoke

Another common complaint is the smell of cigarette smoke. If you’re a smoker or someone at home is, then this is quite expected.

If someone is smoking at home, your air conditioner unit will absorb the tobacco particles through the air filter. So, each time someone smokes, these particles will get into the system and go directly into the air filter.

You might not notice problems at first because these particles will just get trapped in the air filter. However, as these particles accumulate, the particles will loosen and will be released into the air.

As a result, you smell cigarette smoke, even if there’s no one around who is smoking.

What’s the Solution?

When it comes to the cigarette smoke smell, you only have one option: to smoke near an open window or just step outside. This should be able to minimize the smoke particles that enter your unit.

However, aside from this, we also recommend changing your air filter every 30 days. Also, you can clean your AC unit at least once every week or every two weeks. You don’t have to do any deep cleaning as this should be left in the hands of a professional HVAC contractor; just wipe off dust or any particles.

Lastly, don’t forget to schedule air conditioner maintenance at least once a year in the spring.

Burning Smell Coming From Your Air Conditioning Unit

image of air conditioner electrical wiresNow, what if the air conditioner smells like something is burning?

There might be two reasons for this:

  1. The first is that you might not have used your AC unit for a long time. When this happens, the accumulated dust is exposed to high temperatures. It gives off a burning smell.
  2. The second reason is that a part of your unit may have a component that is burning. This could be a damaged wire, the motor, or a cable.

If it’s the first reason, you don’t have anything to worry about as the smell won’t stay for long. However, if the scent lingers, you should turn off your air conditioner and call an expert HVAC contractor for help.

What’s the Solution?

If you smell something burning from your air conditioner, don’t attempt to fix the problem yourself. Always call a professional HVAC contractor to help you.

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Rotten Egg Smell Coming From Air Conditioner

If your air conditioner starts releasing a rotten egg smell, then there could be a decomposing animal inside.

When a body starts to decompose, it will release gases that smell like rotten eggs. It’s highly likely that small animals like rodents, reptiles, or birds have found their way inside your unit and, unfortunately, died.

What’s the Solution?

Once you’ve detected this kind of smell, find the dead animal in your air duct or system to remove it. Make sure to remove any traces of organic matter, and then sanitize the area.

If the area is hard to reach, call an HVAC technician right away to take care of the problem for you. This is also the best time to get your system checked, cleaned, and pest-proofed so the same thing won’t happen again.

Air Conditioner Gas Odor

Methyl mercaptan depicting natural gas leakGas is odorless. So, as a safety measure, manufacturers made sure to add a chemical called methyl mercaptan to give it a detectable smell. It’s almost similar to the smell of rotten cabbage.

So, if you detect a gas odor, it’s definitely one of the things you shouldn’t ignore. This is your best sign that there’s gas leakage and you need to get out of your house.

It’s best to remember that methyl mercaptan is an irritant that can cause nausea, dizziness, headache, and problems in your upper respiratory tract. It can even irritate your eyes and skin. Furthermore, if you’re exposed to methyl mercaptan for long periods, you can go to a coma or even die.

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What’s the Solution?

Once you’ve detected a gas smell, turn off your gas supply immediately. Then, open your windows to provide ventilation and leave your home immediately.

After you leave your home, call up the gas company or a professional HVAC contractor right away. Don’t light up anything while you still detect the smell, as this might lead to explosive sparks.



There are a couple of reasons why our air conditioner produces specific smells. Some of those reasons may be harmless, but there are definitely those that you should not ignore as they can be serious and will potentially be fatal.

From the many smells above, there are those that you can get rid of by simply cleaning and replacing the filter on your air conditioner unit. However, for serious problems like gas odors, call a professional HVAC technician immediately.

Remember, you should never ignore any odors that your air conditioning unit produces. It’s always best to get the problem resolved immediately to prevent any health issues and costly repairs.

Call Skylands Energy Service For All Of Your HVAC Requirements

image of skylands energy service logoSkylands Energy Service offers superior heating and cooling services in Central New Jersey.

We make sure to hire certified technicians who can provide you with excellent services, including tune-ups, repairs, installations, and replacements. Each technician has outstanding knowledge and experience to serve your HVAC system needs correctly.

Skylands Energy Service offers the most competitive heating and cooling service costs in the area. Our maintenance services ensure to improve your comfort, increase your system’s energy efficiency, and reduce your home’s heating and cooling costs.

Need your system repaired or replaced? We’ll recommend the best one for your home and is within your budget. The best part is, all our work is backed with a guarantee to ensure your satisfaction.

If you wish to schedule a service appointment, give us a call today! We also offer in-home estimates at no cost at all.

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