If you notice steam spewing out from under your hood while driving, pull over immediately into a safe location. Turn your air conditioner off and roll down the windows. Turn on your hazard lights. While you are pulling over, cranking the heat up will help if the problem is related to a broken fan or fan belt.
After turning off your engine, allow the radiator to cool for about 30-45 min before removing the cap. If you open the radiator cap before the contents have cooled down, the hot liquid could shoot out and cause severe injury! Be careful.
Touch the radiator cap with your hand and feel for heat. Do not open until cool.
Using a rag, slightly unscrew the radiator cap and listen for hissing as contents will be under pressure. If pressure seems normal, slowly unscrew the cap.