AC Smells Musty? Find the Answer to the Smell Here

AC Smells Musty

If your AC smells musty, then you’ll need to figure out what’s wrong with it, what to do to repair it, and how you can have a working air conditioner again. When the heat outdoors is extreme and the sweat is dripping off of you, then you need a functional air conditioner to survive the hot summer days. 

Does your car’s air conditioner smell bad? If your car AC smells like mildew or your home’s air conditioner has a strong smell, then you’ll benefit from reading this guide detailing the solutions necessary for repairing an AC and removing the bad odor. Keep reading to learn all about it! 

Why Does My AC Smell?

Whenever your AC smells musty, there are multiple reasons why this may be taking place. The possible reasons include: 

  • Growth of mold, fungus, and/or mildew inside the air conditioner system
  • A bacterial build-up in the AC system
  • Old, dirty water clogging up the air conditioner and not draining well
  • Fluid leaks in the machinery of the AC
  • The circuit board and/or fan motor shorted out and led to a burning odor
  • A potential gas leak in the system
  • An animal may have died in the ducts of your air conditioning system

How Do I Get Rid of the Smell in My Air Conditioner?

If your window air conditioner smells musty, there are several different steps you can take to remove the awful scent from your air conditioner and the rest of your home. First, you need to turn off the air conditioning unit and then start to change out the air filters. 

Use bleach or a cleaning solution to wash the evaporator coils as well as the condensate line. Clean off and wipe down the air conditioner unit. Leave it to dry fully. Now you can reassemble all the parts and put the AC back together. 

How Do I Get Rid of the Smell in My Air Conditioner

AC Smells Like Rotten Eggs

If you find that your AC and parts of your home smell like rotten eggs, it often means there could be a gas leak in your residence and it is coming out of the ducts in your AC system. 

A natural gas leak can be deadly to you and your family, as it can decrease oxygen levels in the bloodstream. A gas leak can also catch fire or explode. 


As such, you’ll need to quickly turn off the gas supply at your home and evacuate your house. Everyone should leave the house to stay safe. Now you can call 911 to connect to the fire department. You can also call the gas company instead to report the gas leak. 

Air Conditioner Smells like Gas

Sometimes, a strong smell of gas can emanate from your air conditioner and spread throughout your home. You might also hear a hissing sound that goes along with the scent.  All of this might be a sign of a gas leak, which is truly dangerous and you’ll need to maintain your HVAC device to prevent a leak. 


If you think you have a gas leak, leave your home and contact emergency responders as well as your gas company. If it’s not a gas leak, then the smell may be due to dust burning off, the exhaust pipe removing fuel, or even your garbage can standing too close to your AC. 

You can solve these problems by cleaning your ducts regularly, closing a window or door to remove the direction the exhaust pipe is blowing, or taking out the trash to remove the smell. 

Air Conditioner Smells Like Fish

Air Conditioner Smells Like Fish

Does your air conditioner have a fish stench? While you may think the fishy smell is due to a dead animal in the vents or due to mold growth, this may not be true. It is more likely due to overheated and burned plastic in the electrical system of the air conditioner. 


First, try to turn off your HVAC system and go from room to room to see where the fishy odor is coming from. If there is no odor when turned off, then the smell is likely coming from the air conditioner. Yet, if other parts of the home smell like fish, then it may be due to other electrical components. 

Since overheated electrical components pose a fire hazard, it is necessary to call a licensed electrician to repair the problem. 

AC Smells Like Feet

Does your air conditioner have a stinky feet stench or a dirty socks smell? If so, it may be due to a dirty or clogged air conditioner. It is likely due to old water sitting in the air conditioning unit and not draining effectively. Once it collects into a pool of water, it can develop this terrible scent. 


If your AC smells like feet, you will need to clean it out completely. A thorough cleaning should remove the smell. You may need to take some of it apart, clean it with a cleaning agent, let it dry, and reassemble the AC. 

AC Smells Like Feet

Window Air Conditioner Smells Like Chemicals

A chemical-like smell coming from your window-installed air conditioner could mean a few different things. It might mean there is a refrigerant leak in your AC or it might be due to a build-up of mold. Household chemicals may have also made their way into the air handler portion of the AC. 


A chemical scent is often due to a refrigerant leak, so you should have an HVAC representative come to your home to resolve the leak and possibly recharge the refrigerant. You likely have damaged coils in your AC, which will impair the functionality of your air conditioning unit. The best solution is to have a technician fix the problem. 

Why Does My AC Smell Sour

Why Does My AC Smell Sour?

A sour smell that comes directly from your air conditioning unit is often due to a malfunction of the condensation removal system. Condensation is an effect of the cooling process within the AC. 

If the condensation is not drained appropriately, then it can lead to bacteria or mold growing inside and can cause a sour smell. 


The solutions to a sour-smelling AC include: 

  • Cleaning and/or changing the filters
  • Turn off the AC and clean off the condensate pan
  • Use a condensate pan cleaner regularly to better maintain the AC
  • If you believe your ducts have an excess of mold growth, hire an HVAC technician to clean out the mold and mildew in your air ducts

Air Conditioner Smells Like Cigarette Smoke

If you recently moved into a new home, you might find that the previous residents smoked cigarettes when you turn on the air conditioner

The smell of smoke may also be due to a section of your HVAC system overheating. If the wiring insulation has burned through, then a smoky smell will emanate from your AC. 


To remove the smell of cigarette smoke, you need to take the following steps: 

  • Unplug the air conditioning unit
  • Clean or replace the air filter
  • Use a washcloth to clean out the unit
  • Spray air freshener over the filter
  • Run the air conditioning unit for at least 10 minutes to remove the scent
AC Smells Like Exhaust

AC Smells Like Exhaust

Exhaust fume odors can take place even among AC systems that aren’t generated via gas, specifically when a fluid leak takes place from certain parts of the heating or AC systems. 


If you do smell an exhaust fume coming from your AC, then you will need to contact and hire an HVAC technician to analyze the issue and fix the problem professionally. 

Air Conditioner Smells Like Wet Dog

Does your AC smell like a wet dog? Once again, a wet and musty smell is often due to mold and mildew growth in your air conditioning unit. Fungi and bacteria may also grow inside your AC unit due to the moisture in the coils mixing with spores. 


You’ll need to clean out your air conditioning unit with a bleach solution to remove the wet dog smell.  

Car AC Smells Like Mildew

Car AC Smells Like Mildew

Why does my car AC smell like mildew? You might even find a mildew smell coming from your vehicle’s air conditioner. As such, mold, mildew, and bacteria may have grown in your AC system in the area where moisture collects. 

How to Get Rid of Mildew Smell in Car?

You can purchase a vent and duct cleaner spray that you can use on the vents in your car and remove the odor. However, if this doesn’t work to remove the smell, you may want to speak with a licensed mechanic. 


Now that you know all the possible reasons why your AC may have a smell and the solutions to take to fix the problem, you can enjoy blasting your air conditioning system on hot summer days.