I use the windows to as much as possible. But when the humidity gets high enough, you reach a point where the flow of outside air is not doing any good. So I've been up into the 90s and even low 100s when it is dry and I'm not in direct sunlight with just the windows. But earlier this week, it was 77F, saturation humidity and the sun beaming down on me. No choice, A/C but only set for enough to dry out the air.
Still, there are things to do with A/C:
- highest tolerable temperature - no need to have the compressor running all the time.
- recirculate - so it can dehumidify the air and keep it in the cabin.
- OFF when accelerating or stopped ... just use fan.
- Take the higher speed route - A/C is a smaller fraction of the fuel burn.
Well this is how I handle it.
Also in the summer, I park the car in the shade or where it will be shaded when I'm ready to leave. Of course there is a reflective sun-shield put up over the dash. Finally, I have 'rain guards' on both cars to let the hottest of the air escape. But once I get to the car, I turn the key to ignition and roll down all windows. Then I take down the sun screen and setup the iPad touch to play through the cassette adapter. During the car warm-up drive, no A/C until I can tell if it is really necessary.
Bob Wilson