This is my first Jeep (2000 TJ). I have a newb question. When I bought it, there was a little key/tool that has a half round end. The guy I bought it from said that it is to change the blower vents between the defrost and dash vents. Is this right? If so, where does it fit to do this. Hopefully, this is self explanatory to someone, if not I can post a pic of the tool. BTW, mine only has heat, no AC.