When I turn on the ac or the defrost or heat in the front it barely blows out of the vents. It also causes the van to stall and at other times I can push on the gas pedal and have almost no power. I turn the switch off and power picks up. It happens pretty often so we refrain from using the ac or heater in the front. The back ac works with no problems and as far as I can tell causes no problems. This also seems to be worse in the rain.