switch inside of car is turning AC on when it has a button for AC

so I don't have any thing working. I change the control inside of the car for the heat and AC.. when I turn it in feet and defrost it turn on the AC compressor when it's sitting that has a button for the AC. I switch parts today it worked the first time I turn it on and when I turned it off to turn it back on it wouldn't work. it did the same thing as my old one. please help I don't have any heat in my car.. thanks, Joyce