Upon advice from folks here and elsewhere I replaced the A/C idle up solenoid in my '72, which was stalling out in neutral when the A/C was on. (I recently replaced the compressor and receiver-dryer.) The results are intriguing and, hopefully, not signs of more complications. The part was NOS and clean. Here's what was happening on its maiden voyage: 1) the A/C itself is blowing MUCH colder and more furiosly, almost shockingly so; 2) the intensity of the A/C fan seems to respond directly to how much gas the engine is getting, e.g. when I rev up to shift gears; 3) the engine seems to be working harder, in general, when the A/C is on--a little louder, acceleration not as quick--with the old burnt out solenoid this was not the case; 4) lastly, really weird: the idle-up function clearly kicks in when turning the switch from "off" to "high," which is a quarter-turn to the right, and from there clockwise to "medium" and "low." BUT...when starting from "off" and turning counterclockwise to "low," the engine sputters and dies--like it was doing when the old solenoid was in there. Is this just a design flaw quirk? Or an indication of something more sinister? Any tips appreciated....