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Does your car's air conditioner smell musty? Here's how to fix it

The solution is simpler than you may think.
Switch for a car air conditioning system.
Posted at 10:29 AM, Jun 26, 2023

Have you ever cranked the air conditioning up in your car at the beginning of the summer season and then been struck by a funky smell? If the odor resembled an unattractive mix of vinegar and a dirty sock, the culprit was likely to be condensation.

A car's heating and cooling system can collect water, and if it sits too long, bacteria and mold can form. (Yuck, we know.) The result is a musty smell that gets pumped through the system and into the cabin.

While most of the water that collects in the system releases through the evaporator drain under the car, sometimes a small amount is left behind. Then when the air conditioning system isn't used for a long period of time, such as from September to May, it can create a breeding ground for odors.

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How to make your car smell fresh again

Thankfully, it's not a complicated fix and is something auto owners can do at home. It entails running the AC system and dispensing a disinfectant spray, like Lysol or a special AC disinfectant from an auto parts store, into the plenum. This is the grate where air is pulled into the air conditioning system, and it's located near the base of your wiper blades. It might also be under the hood.

Simply spray a large amount of the cleaner into both sides of the plenum intake vent while the car's interior fan is running on low. Make sure all the windows are open.

Now is also a good time to change out your cabin filter, which may be contributing to the foul odor. Dust, allergens and bacteria can clog the filter over time. You can find replacement filters at your local automotive store or online. Changing them should take less than 10 minutes. Then keep up the routine. Your owner's manual will give you a specific frequency, but a general rule of thumb is every 15,000 to 30,000 miles.


On the contrary, if your car ever smells oddly sweet, or the opposite — like burnt rubber, plastic or oil — it's likely caused by something else entirely. Consult a repair shop for a professional diagnosis.

This story was originally published by Emily O'Brien on