Why Does My Air Conditioner Smell?

Posted on March 17th, 2021 by Bill Stuhr

Spring is almost here which means the heat of summer is right around the corner. Around here, summer is air conditioning season. The cool air from an AC on a hot day can melt your worries away. But without the proper maintenance, you might have to worry about why your air conditioner smells.

Musty Smells

The kind of smell coming from your air conditioner or vents can clue you in to the source of the scent. If you’re wondering, “Why does my air conditioner smell musty?” you might have a mold problem.

Air conditioning systems work by pulling heat out of the air and circulating the newly cooled air into your home. To do so, they run the air over a cool evaporator coil. This process creates condensation, which falls into the drain pan and flows out of your home via the condensate drain line. But if the moisture doesn’t drain properly, it provides a perfect breeding ground for mold and mildew.

Sometimes this moisture finds its way into the air filter. When this happens, the filter may start to take on a musty smell that might resemble a dirty sock. If you notice these smells coming from your air conditioning unit, simply clean or change the filter. Doing so should eliminate the musty smell so you can enjoy your AC worry-free once again.

If a clean filter doesn’t solve the problem, you might have a clog in your drain line or drip pan. It’s best to leave these kinds of issues to the professionals. Ignoring the issue will only make it worse, potentially allowing mold to spread and take root elsewhere in your home. But if you take action as soon as you notice the smell, an HVAC technician should be able to eliminate it in a single visit.

Other Smells

If you notice other foul odors coming from your air duct or AC unit, you should have your HVAC system inspected by a professional. Most of the other common smells are a sign of something more complicated than a dirty filter. But to give you a sense of what the issue might be, let’s do a quick run through of smells that can corrupt HVAC units.

• Exhaust Fumes

If you catch a whiff of what smells like exhaust fumes, there’s a good chance your AC is leaking fluids of some kinds. The refrigerant line is the most likely culprit. The coolants in these lines can be hazardous to the environment and your health. So be sure to have a technician come out as soon as possible if you smell exhaust coming from your AC.

• Gun Powder, Melting Plastic, or Fire

Like any electrical device, the wires and circuit boards of an air conditioner can overheat and start to melt or even catch fire. But if you notice the smell after turning on your AC for the first time in a while, it might just be burning off dust that settled on these components. If the stink dissipates quickly, you should have nothing to worry about. If it persists, call a pro.

• Rotten Eggs

Sadly, rodents, lizards, and other critters often get stuck inside of air conditioners or ductwork and can die there. As they start to decay, they start to stink. If you’re feeling up to the task, you can try following your nose to the deceased. But most people prefer calling in an HVAC tech to handle the problem.

• Gas/Skunk

Your AC doesn’t use gas to keep you cool. So if you notice a gassy or skunky smell, you probably have a gas leak that’s found its way into your ducts. Because natural gas is odorless, gas companies often give it a skunky scent to help identify leaks. If you start to smell gas or skunk coming from your vents, immediately turn off the gas line to your home and contact your gas company to investigate.

Getting Help

Most of the unpleasant smells an air conditioner can make require a service call from your HVAC company. Five Star Heating & Air is the leading cooling company in Palatine, IL, IL. So if you live outside of Chicago and catch a whiff of something coming from your AC, give us a call at (847) 359-4534. We’ll send one of our expert technicians out to identify and solve the problem before you know.

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