I have 5 wires in my old programmable thermostat. They were red, white, blue (C), green, and yellow. I put on my new thermostat, a Hunter 44550, and since it is battery powered, I don't need the blue ...

assuming gm didn't fuck it up (draw your own conclusions), it shouldn't be difficult. typically it's a matter of draining the coolant (not strictly necessary all the time, but you might as well ...