[StingRay]

Depending on vehicle they had some different applications. A/C idle up could certainly be one of them. My 72 had one and I was always under the impression that it was to eliminate dieseling. On the stock 307 it sure functioned that way. If you set the idle at the carb it would diesel like a bugger. If you set the idle at the solenoid it would activate with the key and it would idle at the set speed. Kill the ignition and the solenoid would deactivate and the throttle blades would fully close and starve the engine of air/fuel so that it couln't diesel. Worked like a charm too.