I used to have a problem with this. I even bought one of those carbon cabin air filters and it only helped a tiny bit. After doing the following thing for the past month or so the smell is finally gone for good!

When I turn the vehicle off after using the A/C I press the recirculation button on the A/C control panel. The second LED light near the bottom of the button will light up and you'll feel air coming out of the vents. It will run for somewhere between 15-30 minutes (even though the key is out of the ignition) and it dries out your A/C system, which helps to kill off mold and mildew and the bacteria that create that terrible smell. I've done this for over a month now and it doesn't kill your battery.


I hope that works for you as well!