My wife & I were traveling to San Diego a couple years ago durig the summer and thought we had timed it right to climb the hill on I-8 in the cooler part of the morning. Unfortunatley, we hit in the hottest part of the afternoon and climbed the hill in 114F heat. The Ford pulled my 5th up the hill almost to the top before I noticed the heat getting close to the top (red). I have a question for the long time, expert RV'ers. With a diesel engine, what are the best ways to avoid overheating when climbing a large hill like that one. We turned of the AC about 3/4 of the way up (probably should have started that way) but just curious what other methods could be used to avoid excessive heat build up?