It's possible the condenser coils iced over, not allowing air flow. This happened to us once. When first turning on the air conditioner, set it so it will begin to run, but shut off at a warmer temperature. Wait a few minutes and drop the thermostat a pinch. It will come on and again and cool and shut off again. During the "off" times, this allows ambient heat to melt any ice that forms on the coils. If the humidity is high and the compressor runs non stop, the coils will ice up. Once iced, no air can pass cooling the inside of the camper. All you have to do is shut the air conditioner off for a short while until that ice melts. And repeat.