They design the cooling systems for worst case...
They test Jeeps in Death Valley pulling 5000 lb trailers with the A/C cranked and make sure that they don't overheat... There are signs in Death Valley that warn people to turn off the A/C to keep from overheating the engines...
They make sure that the Jeeps can survive with the A/C on.... If you can make it through Death Valley with the A/C on, then you should be able to handle any other heat...
