I was trailering my two motorcycles to Eureka Springs AR when I noticed my air conditioning when stop work when I would go up a hill. As soon as I would level off the air would come back on. Has this happen to anyone else????

 

I believe it has something to do with the drop in vacuum in the lines operating the AC controls due to the drop in manifold vacuum under those conditions. I seem to remember something about adding a check valve in the line to maintain vacuum during these conditions to help eliminate this condition. I'm sure someone will chime in who knows more about this...

 

Yup, you have a vacuum leak. I'll bet if you look a little closer, it's not actually shutting off, it is switching to the defrost vents. Try the search feature, and you'll get tons of threads about vacuum leaks. This is a pretty common problem on our trucks.