When you switch on your aircon you get this not-so-good smell inside the car' what causes it and how do you get rid of it?

When you switch on your aircon you get this not-so-good smell inside the car' what causes it and how do you get rid of it?
inside of the car is a component called an evaporator. this component has air flowing through it. due to normal operation, fine dust and any air born particles stick to it because it gets moist then mold can start growing on it. locate the a/c evaporator and spry it with easy-off oven cleaner (lemon scented recommended) let stand for about 15 minutes, respray, turn on a/c with car running, let vent to outside atmosphere until excess vapors are gone.