I was attempting to install a smart thermostat that came with a c wire adapter. I thought I needed the adapter so I unhooked the wires at my control panel then noticed that there was a blue wire hooked up to to C wire spot. Started putting wires back in and saw a loose black wire that I did not unhook. The black wire at the thermostat was hooked up to a spot labeled W2. I'm assuming it came unhooked when I was pulling the other wires out. My only places to put it are marked AL1, AL2 or A. This is a geothermal system with emergency heat strips. Here is the wiring diagram. (https://preview.redd.it/control-panel-wiring-help-v0-ukj9j966blud1.jpeg?width=2268&format=pjpg&auto=webp&s=1759e0ea31d1a0d627b51ba51250df9752ab1b8d)