Here is the diagnostic procedure from the 1998 Grand Prix Service Manual and the schematic. I'm stuck! I've replaced the original digital climate control head unit (CJ2) with two different used units and still get only a 0.01 to 0.03 v signal from terminal C11 which provides the signal to blower control unit where the factory spec is 0.5 to 7.0 volts. (The circled steps are the ones I used.)