First, turn on the car’s interior fan on the low setting and open up the car’s windows. Get a disinfectant, such as Lysol or an AC disinfectant from an auto parts store, and spray it into what’s called the plenum.
The plenum is a box that connects to your heating, ventilating, and air conditioning system, and the intake can be found at the base of your windshield, where your wipers are located. You’ll see vents there, and that’s the plenum. That’s where the air that goes into your heating and cooling system comes from.
Spray the cleaner liberally into both sides of the plenum intake vent and the fans will pull it into the system, where it will kill the bacteria and help get rid of that musty odor. You’ll want to keep your windows open to help air out the car. If you have a cabin filter, remove that before you spray the disinfectant to help it move through the system. It might be a good time to change it, too, because a dirty filter can prevent optimal airflow. Cabin filters are usually pretty easy to get to, often mounted behind the glove compartment door.
To help maintain your vents in the summer, turn off the air conditioner and let the fans run for a few minutes before turning off the car’s ignition. This will help clear out some of the moisture that forms in the AC vents.
