The A/C-heater control light bulb wire should be a grey wire that gets its voltage from the instrument cluster grey wire. You can test for presence of the right switched power with a test light or multimeter. Yes, you can tap into that wire for both bulbs. If you don't see that grey wire set up, I recommend connect both A/C control light bulbs from a new grey wire that you plug in to the fuse panel. If you plug it in to the terminal marked PNL LTS (notice the little arrow pointing to the terminal), it will be the same source of power the instrument cluster gets, which works when the lights are on and twisting the headlight switch dims the cluster and A/C control lights. LED bulbs are not usually dimmable, or if they do dim, they don't dim very much before just going out.
