2% grade for 15 miles?!?!?!
Could be the location of the sensor? Do you know what the temps are to activate the low and high speed of the fans as well as when the t stat opens? My honda has a high temp before any alerts goes off, like 230 degrees, but when I see the temps go to 200 I start to get worried as low speed for the fan is at about that range and kicks off at 190.
With ac on my temps stay at 187 no matter the outside temp, but I also use water wetter in my cooling system.
