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Why Does My Car Air Conditioner Smell Musty?

air conditioner smell

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Wondering what the source of that musty air conditioner smell coming out of your car’s air vents is? Unfortunately, that unctuous odor could pose a significant risk to you and your family’s health.

It can be important that you make every effort to eliminate the causes of musty smells right away to help prevent toxins from entering your airway and lungs.But the bad AC smell isn’t going to go away on its own. It will take a little detective work and a bit of elbow grease, but there’s a good chance you’ll have success removing AC odors if you follow this quick guide.

Here’s what you need to know about diagnosing the source of a musty air conditioner smell and how to eliminate it.

What Are the Causes of Musty Smells in Car Air Conditioners?

The most likely source of the bad air conditioner smell in your car is your AC evaporator. Air conditioner units produce a lot of moisture. That’s normal.

However, when moisture is left to accumulate, it can cause mold, mildew, and fungus to grow.

When your AC unit blows cold air through the evaporator, it picks up the spores of that mold and fungus. Then the spores blow right into the faces, orifices, and lungs of you and your passengers.

Unfortunately, inhaling mold can be dangerous. It can make people with sensitivities very ill. Mold is especially dangerous for those with allergies or asthma.

The following components of your car’s AC unit are the most likely places to grow mold and produce the musty odor you want to remove.

Clogged Evaporator Drain

When your AC unit is functioning properly, the moisture it produces evaporates. There is a drain hole on the evaporator that allows the accumulated moisture to escape.

It’s easy for the evaporator drain hole to get clogged with leaves and other plant debris. When the evaporator gets clogged, the moisture from the AC cannot drain.

The moisture that collects inside the evaporator is the ideal environment for mold to grow and thrive.

You’ll know your evaporator is clogged if you don’t see a puddle of water underneath your car’s engine when your AC is running. Another indicator of a clogged evaporator drain is wet patches on the floor of your car.

Clogged Air Vents

Another possible source of the musty air conditioner smell is your car’s air vents.

Normally, debris that gets into a car’s AC unit gets caught by the cabin filter. When this doesn’t work, it is very common for leaves and other plant matter to get stuck inside the manifold.

With nowhere to go, this debris collects in the air vents. Combined with the moisture from the AC, the debris begins to grow mold as it decays.

Clogged Cabin Filter

Finally, if the smell isn’t coming from the evaporator drain or the air vents, it most likely coming from the cabin filter. As mentioned, cabin filters prevent debris from entering the air vents.

Your cabin filter should work properly as long as you make sure to replace it every 30,000 miles or according to the manufacturer’s guidelines.

If your cabin filter is too old or doesn’t fit properly, it can absorb moisture and produce mold.

How To Get Rid of a Bad Car Air Conditioner Smell

If cleaning AC units sounds like a chore, you’ll be glad to know that’s the absolute last step in getting rid of the bad AC smell in your car. Before you get your yellow gloves on, try checking the rest of these fixes off your list.

Unclog Your Evaporator Drain

To do this you’ll need to locate the evaporator drain hole. It’s black and resembles the nut on the end of a garden hose. If the drain hole is dry while the air conditioner is running, it is very likely clogged.

To remove the clog, get a poking device like a paper clip or wire clothes hanger and insert it into the hole. Push it in a few inches and move it around. When water comes out of the hole you’ve unclogged it.

Remove Debris From Your Air Vents

Check under the hood of your car to see if there are any leaves or other debris blocking your air vents. If you find any, remove it using your hands or a vacuum hose.

Replace Your Cabin Filter

There’s no good way to clean a dirty cabin filter. The best thing to do is replace it.

Clean Your Car AC Unit

If none of these solutions rid your car of that bad air conditioner smell, you probably need to clean your AC. To do this, you’ll need a mold prevention spray.

You can use a specialty spray, a common cleaner like Lysol, or make your own natural cleaner with vinegar and water.

Turn your AC off and spray the cleaner into every air vent in your car. Then turn the AC on and blast it to circulate the cleaner around the entire system.

If this doesn’t work then it’s probably time to learn about replacing AC units. Having a properly functioning car air conditioner benefits your car and your health. It might even save you money on gas.

Know When To Turn Your AC Off

The best way to get rid of a bad air conditioner smell is to prevent it. When it’s hot out, the majority of drivers probably wait to turn off their AC until they arrive at their destination.

But while you’re driving, your AC has been producing moisture. That moisture is now all over your evaporator when you turn your car off, creating the perfect conditions for mold to grow.

To prevent this from happening, get in the habit of turning your AC off a few minutes before you reach your destination. That way your evaporator has time to dry off before you park your car.

Car Maintenance Solutions

Want to get rid of that bad air conditioner smell once and for all? Start by diagnosing the problem (hint hint, it’s your AC evaporator), and then try one of the simple fixes listed above.

If that doesn’t work, talk to an automotive expert about getting an AC replacement. It’s important to keep up with car maintenance and nothing gets more wear and tear than your tires. Treads is on a mission to make tire purchasing and maintenance convenient for everyone on the road. Sign up for one of our hassle-free subscription plans so you won’t ever have to give your tires another thought.

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