Car will not switch to Auto from Econ

I have a 99 Cadillac Deville D'elegance and the temperature control system on the dash will not switch to Auto from Econ. Basically i cant use my AC at all. Also the dash says low refridge sometimes then goes away. i dont know if these 2 issues are connected but i would think they are. Even when the temp outside is 30 degress and i want it to be 70 in the car, it still wont change to Auto from Econ. Anyone have any ideas?

It will not go to auto if the freon is low, thus the dash warning.

Thank you, i will get freon in there and see if that settles everything. I appreciate the help.