1997 Pontiac Bonneville Electronic Climate Control ECC

First the ambient temperature sensor near the radiator needs to be replaced, then check if the compressor comes on when you turn on the A/C, hot air may be an indication you are way to low on refrigerant. Next find the small black vacuum line the goes through the firwall, follow it to both ends, outside it will take you to the manifold supply and a small tank, either the tank is leaking or the hose is not connected, or has a hole in it. Inside it plugs into the control head, and that may also be NG check for vacuum on the inside end of ir.