We have always run our dash air in the MaxAir position(no outside air is pulled in) 99% of the time, and occasionaly use our overhead dash fans on low to help move the air around. This keeps the front of the coach very comfortable back about 6-8 ft when outside temps are in the mid/upper 80's or cooler. After that, we start the gennie when outside temps start rising and turn on the front overhead coach air to supplement and set it's fan on high. On rare occasions, we have run the second coach air when in places like Az, NM, NV. Our vent temp exiting the dash air will remain in the 42-47 degree range regardless of how hot the out side temp is. Bottom line, keep the dash air on the MaxAir position, use the overhead fans on low if present, use the gennie and roof air(s) when needed. They're meant to be used and should not be sitting idle.