A/C can't turn off?

I found out that my A/C can't be turned off. I assume that A/C should only be on when you turn the switch to "AC" or "Max AC" in the temperature control panel right?

When that switch on my '98 3.8l is not on either of the AC or Max AC, but on for example, floor vent, and if I dial the temperature all the way to the coldest, then the A/C is on.

Is this only on my car or Ford makes it that way?

A/C is also on in the defrost mode, unless the outside temp is below freezing. It should be off in all heater modes.

If my dial is on one of the heat-modes only, and the temperature dial is set all the way to cold (blue), then my air-conditioner comes on too.

My '96 has the A/C active in all positions except the dashboard VENT and the OFF positions.....