If you drive a car that was manufactured before 1994, it’s possible that the air conditioning system is still using R12. This refrigerant was deemed to be dangerous to the environment, and it must be replaced
If your car's air conditioner isn't blowing cool air, then you've likely lost some of the refrigerant, usually due to a leak. You can recharge the system yourself with a charging kit and some refrigerant, as long as your car uses r134a...