I have mildew in my 05 Grand Am cooling system - what do I do?

blow it up!!!! kill the car lol!!!! or you could use an ozone generator that should fix it that's what i did whin we had a car that had mildew in the ac systom also if you live in a dry climate it wont grow in the first plays. good luck ozone is good stuff it kills all kinds of bad stuff Google it