Witht going into too great detail, “psik reisha” means that the result of the action is inevitable- when you cut a head of something living, it will die ,for sure. Here, the fact of opening the door is not the direct cause of the airconditoner working(heat in the winter) starting- there are a myriad other reasons- people ni the room, the hot weather, doors opening from other rooms, etc,,,,hence, it is “dovor she-ein miskaven’ and not a “psik reisha”.
I would submit that it also “lo nichei lei’ because he doesn’t want the action of the door opening (the airconditioner starting)as a result of his action.