Updated at: 28-09-2022 - By: Sienna Lewis

When your air conditioner begins to disperse noxious odors throughout your home, even the coolest air can’t make you feel better. It can easily turn your home into a place of misery. There are times when a nasty smell coming from your air conditioner might be dangerous and necessitate immediate assistance from a professional. How can you get rid of these odors, and what are the causes?

7 Reasons Why Your AC Smells Bad When Turned On

1. Dirty Air Filters

Air filters are designed to catch dust and other airborne particles, but if they aren’t updated on a regular basis, mold and mildew can grow on them, causing a musty smell to permeate your home. Your air conditioner’s effectiveness will be negatively impacted by dirty air filters, which can lead to a host of other issues. As a result of these factors, it is critical to inspect and replace your air filters on a regular basis.

Air Conditioner Smells: 6 Reasons Why Your AC Smells Awful & Solutions

2. Dirty Evaporator Coil

A filthy evaporator coil is another major cause of poor AC scents. Refreshing air can be circulated throughout your home thanks to the evaporator coil’s conversion of liquid refrigerant into gas. Mold and mildew can grow on these coils if there is too much moisture in the air. While it’s possible to clean these coils on your own in some cases, it’s always best to enlist the help of a professional. With a soft brush and mild detergent combined with warm water, simply locate the coils, which are normally located within or nearby your air handler (the inside device).

3. Problems in Your Ductwork

Mold and mildew can grow in your air ducts if they are damaged or have leaks, causing foul odors throughout your home. Leaky air ducts can cause uneven cooling throughout the house, even when the AC is operating for extended periods of time. Repairing tiny tears on your HVAC system is doable, but hiring a professional HVAC expert is recommended. They use specialized, safe equipment to clean the ducts and seal them to prevent further leaks or damage. They’ll also be able to look for any additional issues that may be lurking in the system.

4. Clogged Drain Lines

It is possible for a variety of microorganisms, including algae, mold, mildew, and bacteria, to grow if your condensate drain line is clogged up. When your heat exchanger is working, the drain lines are supposed to remove any extra moisture from the system. But malfunctions, damage, and normal wear and tear can all cause issues. It’s possible to solve most clogs at home with just a few ordinary household materials and a small amount of time and effort. However, if the problem with your drain line is more significant, you may need to hire a plumber.

How to Remove Musty Smells From Your Portable Air Conditioner | HVAC Training Shop

5. Stagnant Water in Drain Pan

Water might accumulate in the AC drain pan if the drain lines become clogged. Fungal growth, mildew, and many other nasty things thrive in stagnant water. If you see any water in your AC drain pan, use a towel or a wet/dry vac to remove it, and then wipe the pan with vinegar, bleach, or a similar cleaning solution. If your drain pan is clogged, you’ll need to call a professional to fix the problem or unclog your drain line yourself.

6. AC Smells Like It’s Burning

When you first turn on the heater for the cold season after a lengthy period of time without using the AC, you may notice a burning smell as the unit burns off dust that has accumulated during the period of inactivity. After a few uses, this should go away. Professional help may be required if the scent persists, or if your unit hasn’t been dormant for a long period of time. There are a lot of electrical components in air conditioners, and they can catch fire. Call an HVAC professional instead of trying to fix this problem yourself.

7. AC Smells Like Chemical Fumes

If you notice weird odors coming from your air conditioner while it is running, you may have a refrigerant leak. During a cooling cycle, your air conditioner distributes cooled air throughout your home thanks to refrigerants like freon. These compounds are fantastic for cooling the air, but they can be harmful if they come into direct contact with the skin. Refrigerator poisoning, which can be lethal if inhaled, can result from the inhalation of refrigerant.

What Causes Dirty Sock Syndrome?

As soon as you go from using your heater to your air conditioner, your socks get dirty. It all begins with a buildup of dust on your air conditioning unit’s evaporator coil. Mold and bacteria thrive in humid conditions thanks to this dust’s ability to retain moisture.

If suitable air filters aren’t installed and updated on a regular basis, this buildup could happen faster. It’s also possible that regular maintenance isn’t being conducted.

Is Dirty Sock Syndrome Dangerous?

There is fungus and mold on the coil that is causing the stinky socks to come out of the dryer. Mold and mildew should be addressed carefully, even if the scent isn’t harmful. Asthma and allergies can cause an increase in wheezing and coughing in those who have them. It is possible to have a professional technician fix Dirty Sock Syndrome.

Air Conditioner Smells: 6 Reasons Why Your AC Smells Awful & Solutions

How is Dirty Sock Syndrome Treated?

Compressed air and specialized chemicals are used to thoroughly clean the evaporator coil as the first step in the process. Coil cabinets, where evaporator coils are often housed, are difficult to access without the proper tools and experience. Professionals are needed for this task. If you’re dealing with an older air conditioner, you’re more likely to encounter this issue.

Your air conditioning unit may need to be replaced, or it could be time to clean it thoroughly to see if the problem persists.

What If My Air Conditioner Always Smells Bad?

If your air conditioner smells bad constantly, the problem is likely not Dirty Sock Syndrome. It could be because there are dirty drain pans, malfunctioning drain lines, or other issues. A precision air conditioner tune-up can correct some of these issues and increase your system’s overall efficiency.

Dirty Sock Syndrome may not be to blame if your air conditioner smells terrible all the time. It’s possible that the drains are clogged, the drain pipes are broken, or something else is causing the problem. Some of these problems can be resolved and your system’s overall efficiency improved with a precise air conditioner tune-up.

Improve Your Air Quality With Complete Air Mechanical

At Complete Air Mechanical, we have experienced HVAC professionals who can ensure energy efficiency for your home or business. We provide services in Orange, Osceola, Seminole, and Volusia counties, and we offer financing options.

At Complete Air Mechanical, we have a team of HVAC experts who can help you save money on your utility bills. Service areas include Volusia and Osceola Counties as well as Orange, Osceola, Seminole, and Osceola.


Great! When the air conditioner is running, it emits a foul odor. Infestation by fungi, filthy coils and wires, worn-out motor, sewage, dead animals, and gas leaks are some of the possible causes.

So, if your air conditioner is emitting an offensive odor, call in a professional repairman right once. Please click here for additional information. I appreciate your time and interest. I’ll see you later!