Is there a funky smell in your car, especially when the air conditioner or heater is on? If it smells musty—say, like a sweaty sock—the car care experts at Consumer Reports have some easy ways to defunk your car’s air.

What you’re probably smelling is from the condensation that comes from the evaporator inside the heating and cooling system. Basically, water collects in that area and, if it sits long enough, creates the musty smell.

Most of the water is meant to exit your car through the evaporator drain under the vehicle. You’ve probably seen a small puddle of water under your car. But sometimes that water collects in the evaporator, and if it sits in there for a while, bacteria and mold can form, causing that smell.

The good news is that the solution probably won’t require a trip to the mechanic. This is an easy fix you can do yourself.

First, turn the fan to the low setting and open up the windows. Get a disinfectant like Lysol or an A/C disinfectant from an auto parts store and spray it into the climate system’s air intake, also known as the plenum.

The plenum can be found at the base of your windshield where your wipers are located. That’s where the air comes from that goes into your heating and cooling system.

With the engine on and interior fan running, spray plenty of cleaner on both sides of the plenum intake vent and the fan will pull it into the system, where it will kill the bacteria and help get rid of that musty odor. Keep the 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, and changing it yourself can save you money and time.

Another source of smells could be the sunroof. There are small drainage holes on the sides that sometimes get clogged, allowing water to seep into the roof’s liner or even drip onto the seats.