It is my understanding that the dash air in the MH was never intended to cool the entire coach while traveling. It is intended for the driver and front passenger. If it is working properly it should blow approximately 50degs when the ambient temperature is 70. On my F53 I set the fan to high, the temp to its lowest setting and press the recirc and vent buttons. I have driven considerable miles with the outside ambient temperatures are in excess of 100 degrees and I have yet to be uncomfortable, heck my wife even closes one of the vents blowing on her as she feels it is too cold. I have never ran the coach AC's while driving. I would not hesitate to do so if I were the least bit uncomfortable.