!Help! 1985 A/C climate control panel VS 1988

[ISX_15]

I have aftermarket installed AC, the AC button originally is a 3 wire, one wire is grounded.
The new climate control box I got from a 1988 , the AC button is a 2 wire.

Is the extra wire on my old AC just for the illumination if switch is ON? If so, how would I rewire the new climate control box? rest is plug and play.

 

[ISX_15]

for context, i wont do any messing about with the AC wiring until its fully complete and I can verify everything functions, but this was just a idea, since the new controller is alot cleaner.