a/c compressor always running

The a/c compressor on my 98 Taurus wagon runs when the heat or a/c is on. I read in the manual that the compressor may be activated when the defroster is on but mine runs even when the panel/floor configuration is chosen. Is this normal?

Yes, this is normal, at least as far as I've seen. For some reason Ford thinks we don't know when we want to turn our ac on. The compressor should RUN in: MAX A/C, NORM A/C, PANEL/FLOOR, AND DEFROST. It should be OFF in :VENT, OFF, FLOOR.

" PANEL/FLOOR, AND DEFROST"
I think it's used on these settings to remove excess moisture,
which makes the windows fog.

The a/c compressor kicks on to give your a/c system exercise. Sounds weird, right? Since most people don't run the a/c in the winter (common sense), they run the possibility of allowing moisture to settle and corrode the compressor and lines.

The resulting disuse during the winter would sometimes cause leaks in the summer when the a/c was put to work. Ford resolved this issue by causing all settings except "OFF" and "VENT" to engage the compressor and "exercise" the a/c system. On my older model, this causes a noticable drag on acceleration, however my newer Taurus is barely noticable.

So don't try to disconnect or bypass the system. Exercise your a/c if you want it to work next summer.