94 Concorde ac heat problem
 

Hello all, I would first like to thank all for reading my post and possibly helping. My mom has a 94 Concorde that my dad would take care of and do the maintenance on. He unfortunately passed away last weekend and I am trying to step in and help my mom out. The problem is the car has both heat and ac which work great, but my dad was doing something manually to switch between heat and ac when the time of the year came. So when it was winter, only the heater would work, and In the summer he would switch something to make only the ac work. My mom remembers him going under the dash somewhere on the drivers side and switching something in order to get the ac to work. I have tried looking up under the dash but honestly have no idea what he would mess with in order to manually switch the systems. If anyone has any leads or ideas of what he could have possibly been messing with I would appreciate all insight. Thanks