I have a 2008 Winnebago Voyage on a Ford Chassis and the AC has stopped working on MAX. Here is what happens. In normal the AC works OK, I think I need a recharge but that's easy. When I shift to MAX AC and accelerate all the air stops coming out and does not come back even when I slow down. I go to normal and the air comes back. If I come to a stop and turn MAX AC on the air sometimes blows but as soon as I start to gain speed it dies out. Any ideas?