I have a 99 I'm working on and the issue is that every time you you press the mode butt on on the digital climate control it changes the the temperature instead,

So it's on face only and blowing outside temp air than everytime I press mode it only gets hotter and press again and temp gets even hotter but once you come back to face setting it's back to normal outside temp,

So instead of actually adjusting the mode door it's adjusting the air temp, I tried 3 climate controls and it's not it, I changed the air mix door just to see wat happens and it's not that either, I don't understand why , by pressing mode, it's powering the air mix door, anyone ever see something like this because I sure haven't

 

Was the system working properly before and then just recently start acting up?