Unusual Air Conditioner Smells: What Are They & How To Fix Them

image of a homeowner plugging ears due to air conditioner smells

A working air conditioner should hum quietly and not produce air with any distinctive noises or air conditioner smells. The scented air coming out of your air conditioner should be neutral, not distinctive, weird, or strange.

So what does it mean if you’re noticing an unusual or, worse, an offensive odor every time you turn the air conditioning unit on?

This could be a sign that something is up with your AC unit, and you need to get it checked out. Unusual HVAC odors are not normal for a working air conditioner. Since you are breathing in this conditioned air, it is important that you need to get your unit checked right away. You certainly don’t want to be breathing anything that is potentially harmful or dangerous!

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Common Causes of Air Conditioner Smells

Read on to know what kinds of smells are normal for your air conditioner and which odors mean that there’s a problem that needs fixing.

Moldy Air Conditioner Odors

image of mold that was on air conditioner

When you notice a moldy, musty smell every time you turn the air conditioner on, this could be a sign of air conditioner mold. Mold is very common in many air conditioning units, especially in units that rarely get cleaned. Mold in the central AC unit is likely a result of water trapped in drip lines, the ducts, or the drain pan. As temperatures rise, these moist areas become a prime breeding ground for mold, mildew, and fungi, which get blown through your air conditioner when it is turned on.

Another culprit is dirty or clogged filters. Ideally, filters should be changed every few weeks because they tend to accumulate dust and grime. Filters may also be exposed to moisture, and this can lead to the growth of mold and mildew in the filter. Filters that have not been used for quite some time, even if they are clean, can also produce musty and stale-smelling air when turned on.

Solution: Prevent water from accumulating in the ducts and drain pans by looking for leaks and draining water regularly. Clean filters regularly as well. If you wash your filters, make sure these are dry before you pop them back into the air conditioning unit to avoid further mold growth. Better yet, schedule regular air conditioner maintenance every year. Your HVAC technician can look for leaks, prevent the accumulation of water in the ducts and pans and ensure that your filters are not dirty and clogged. Annual tune-ups can not only figure out what’s causing these weird smells, but they can also help you prevent these issues from cropping up in the first place.

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Cigarette Smells

Cigarette and tobacco smells are not unusual if you have family members who smoke. Air conditioning units can absorb cigarette particles into the filter. As you turn on the air conditioner, these cigarette smoke particles get pushed back out again with the cold air, causing you to smell the cigarette smoke. If you don’t clean your filters regularly, cigarette and tobacco smoke residue can stay in your filters and produce this distinctive smell when the AC is on.

Solution: Encourage smokers to smoke near open windows or outdoors. Change your air conditioner air filters every 30 days and regularly dust off the unit to prevent the accumulation of cigarette smoke particles. Wash your filters if they are washable to thoroughly remove cigarette and tobacco smoke residue. Regular air conditioner maintenance can also help keep your cooling system free from smoke particles.

Burning Air Conditioner Smells

image of air conditioner electrical wires

If you smell something burning when you turn on the air conditioner, turn it off at once. It could be a burning AC component, such as a damaged wire or a busted motor. Short-circuits in the electrical boards inside your air conditioner could also be causing this burning smell. Another cause for a burning or smokey smell is dust, especially if you are turning your air conditioner on after a long time of unuse. Dust that is rapidly exposed to high temperatures can burn up and produce that smokey smell. This smell should last for a few seconds. If it doesn’t, turn the AC unit off and call your HVAC technician.

Solution: Always call a professional HVAC technician when you smell something burning. The cause could require complicated repairs that only a professional can do, and amateur attempts can only damage your air conditioner without fixing the problem.

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Rotten Egg Smells Coming From Air Conditioner

If your cooling system is emitting a rotten egg smell or any smell that suggests rotten organic matter, you may have a decomposing animal inside the unit. Rotten foul smells are often caused by gases produced when an animal decomposes. Small animals like rodents, reptiles, and even big insects can crawl inside your AC unit and die there, causing these smells to form.

Solution: Unplug your air conditioner and open up the filter compartment to see if there is an animal stuck there. Clean and sanitize the area to remove traces of the animal and odor. However, the better solution is to call your HVAC technician. They can open the entire air conditioning unit to perform a complete inspection and remove any decomposing material. Your technician can also sanitize and pest-proof your HVAC unit to prevent this problem from occurring again.

Gas Odor

Methyl mercaptan depicting natural gas leakMethyl mercaptan is one of the gasses most commonly found in household gas leaks. If you smell gas that smells like rotten cabbage when you turn your air conditioner, you may have a gas leak. Methyl mercaptan can irritate the lungs, eyes, and skin. It also causes nausea, dizziness, and problems in the upper respiratory tract. Prolonged exposure can be deadly.

Solution: Turn off the air conditioner, open the windows to allow the gas to dissipate, go outside, and call your HVAC technicians. Make sure that you don’t stay in the immediate vicinity to avoid inhaling the gas.

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A working air conditioning system without any problems should emit air without any strange or unusual smells. There are various reasons why strange or unusual smells may be emanating from your air conditioner. While many of these are harmless, they are often telltale signs that you need to inspect your unit for potential problems. Some smells, like dusty or musty odors, can easily be remedied with regular cleaning, filter changes, and maintenance. However, other smells such as those that indicate a decomposing animal, burnt parts, or gas leaks require professional attention.

Do not ignore any unusual smells coming from your air conditioner, whether it is turned on or off. Fixing the cause of any unusual smell can help you prevent small problems from getting worse and helps you avoid costly repairs down the road.

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Call Miller Oil Company For Superior Air Conditioning Services

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Miller Oil Company provides outstanding heating and cooling service for clients in Hartford County, Connecticut. We hire only the best. Let us send out a certified technician who will provide you with exceptional HVAC tune-up service, timely repairs, proper installations, and cost-effective replacements if needed. Our techs bring the knowledge and the experience to properly service your HVAC system.

Miller Oil Company guarantees you will get competitive heating and cooling service costs that fit your budget. The maintenance service we provide is sure to improve your personal comfort, as well as increase your energy efficiency. This will, in turn, reduce your home’s cooling costs. If you need any HVAC repair or have to replace the system, we will recommend the best unit for your home while not going outside your budget. We back up our work with a guarantee to make sure of your complete satisfaction. To schedule your own service appointment today, give Miller Oil Company a call. Be sure to ask us about the free, in-home estimate service we provide.

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