OK so I have tried an N channel MOSFET and tried hooking it up every way I could. I possibly could have damaged it but nothing looks burnt or smells. The MOSFET is RFP30N06LE that came with the kit. I Belive that the Arduino output needs to go to the gate. I'm guessing that the source in this case should be the wire coming from the Mercedes fan controller and the drain is ground. That's just not working.