Hi I have a 2010 Expedition EL XLT and for the last two days it’s been overheating while driving in town and while driving slow. If I get out onto the highway it cools back down to where it need to be. The a/c also blows hot air while it’s pegged out on hot. Anyone know where to start to fix this problem or can you give me an idea what’s going on? I just purchased this vehicle three weeks ago.