1995 Suburban A/C problem: While driving, The ac went warm and allair directoed to floor vents. The A/C and Recirc buttons will not light up and air is always directed to floor vent no matter where the selector switch is positioned. The rear controler seems to work normally as does the rear defroster switch. Any ideas on how to troubleshoot?

Optional Information:
1995 GMC suburban 5.7L

Already Tried:
Disconnected battery, checked all fuses in owner's manual, checked heat and a/c control in the dash, unplugged and reset all the little plugs on the controler's circuit board and checked visually. I tried to charge system, but the compressor never engages, therefore it doesen't take a charge.