[brucepick]

On the '96-2000 Civic it seems the compressor stays on as long as the "A/C" button is activated and the fan is running (it lights up green). Adjusting the temperature slider only seems to add heat from the engine coolant and leaves the compressor running. It's interesting to know that some other cars still use a thermostat to switch the compressor on and off like all our other older cars did.

When I do need the a/c either for cooling or for keeping the glass clear, I run the system on recirculate and cycle the compressor on and off via the "A/C" button. It's very rare indeed that I run the compressor without the "recirculate" setting switched on.

If only keeping the glass clear, I find it doesn't need to run much of the time, maybe 10-20%. If it's truly hot out the percent on time can definitely go higher. Mostly I can run the fan on speed "1" but sometimes I want more.

Like others wrote, I try to have the compressor on for downhills and off for uphills but that doesn't always work out. In those situations, I remind myself that I'm still getting probably 2x the mpg of most passenger cars and even better when compared to all the pickups and SUVs.

I also use a collapsible sun shield. If I need to get hot air out of the car after it's been sitting, I'll drive a couple minutes with windows open and compressor off