The cabin vents smell like mold and mildew. It's worse during humid days. I'm pretty sure the AC has something to do with it (since it smells bad when I turn the AC off and keep the fans blowing) but maybe there are are multiple problems that all seem like one. Time doesn't seem to really fix it, and I don't actually use the AC very often.

I've looked this up on many forums and there isn't really a consensus. I've heard spraying with Lysol and cleaning out the entire AC system as two main options. Lysol basically just masks it for a while. Replacing the cabin air filter doesn't really do anything.

What's the best way to fix the cabin air vent smell?


As far as I understand it, your pollen filter is filthy and should be cleaned or replaced.

  • I agree ... changing the cabin air filter is a great first step into solving the smell issue. Most people don't understand these should be changed out about as often as you change the oil. May 20 '15 at 12:36
  • I just want everyone to know that this has been replaced a few times and it's definitely not the problem. I overlooked mentioning since it's almost common sense :-P This is because mold/mildew smells must be coming from within the air system (after the air has gone through the cabin air filter)
    – s g
    May 20 '15 at 15:54

Here is what solved the same problem for BMW E39:

  1. Cause: The smell is due to bacteria in the air-duct.

  2. Solution: To solve it you need something with antiseptic action to eradicate the bacteria. There are many Antibacterial Cleaners for Automobile Ventilation System, however, I used simple and cheap pharmaceutical Salicylic alcohol 2%.

  3. Procedure:

    • empty the Salicylic alcohol 2% into any available window spray container.
    • spray into both ends of the ventilation system, for the outside end, firstly remove the air filter.
    • finally, turn on your air conditioning for, at least, 15 minutes on heating mode.

P.S. I did this 3 years ago when I bought the car and there is still no smell.


Air Vent Odor

This issue is bacteria in the ventilation system.

This is not related to charging the air conditioning system as some have indicated. They are separate systems and you do not get Freon in your cabin by using the air conditioner.

The ONLY way to attack the problem IMO, is to;

  • remove the vents from under the dash and clean them out.
  • Change any air filters for the system.

Knuckling down and tearing it apart to clean it is the only true path. Anything else is less is a temporary (short term) solution.


The best way is to fight the problem, not the symptoms. Lysol only lasts for a while and the bad smell will return eventually. The AC is the cause of the bad smell and you should refill the AC system. I don't know for sure, but the gas you might need could be Freon. Check the vehicles owner manual to be sure though.

Before you get started, put your car on jack stands and check for any leaks in your AC system (cracks in hoses, tubes that have worn out). After this you should bleed the AC system and recharge it with the proper gas. It might cost a few bucks, but after this you'll have an AC without the smell and the air will be cooler too!

See also: http://www.epa.gov/spdpublc/title6/609/recharge.html

edit: After rereading your question, I noticed you mention that the smell is still there if you turn the AC off and keep the fans on. Try to clean your interiour (cabin) filter first, before you bleed your whole AC system.

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