I have a 2016 Base…have an issue if possible over heating. When cruising at 80-85 miles per hour, if I try to increase speed the AC starts blowing warm air and the temp rises close to 250. As soon as I slow down it comes back down to 200 and eventually AC blows cold again. Antifreeze seems to be at full level. Any ideas before I spend the $300 to diagnose with dealer.