My A/C system works well but the compressor disengages when I turn the blower to max. The blower works great at all speeds but I could really use that compressor function at full fan speed. The variable speed resistor checks out fine too. I'm stumped.
There is a thermal limiter (superheat) switch under the hood that has popped. Follow the wires from the compressor to where that critter is clipped on. It usually pops when your system is low on refrigerant...if you are still using R-12. Talk to your local AC guy, or PM me if that pans out.
Have you got any pictures or a diagram? I had the A/C system restored about a year ago, new hoses, R-12, etc. so I figure the thermal limiter switch must have popped before I got the car. I even installed a new engine wiring harness but never saw the limiter switch you are talking about. Thanks for your reply, Lee
Think the superheat switch was introduced in '72. Get the AC control panel out of the car & bench test it. Might work with it in the car too but very difficult to access. The compressor will not come on until the fan blower is set up to about mid-level speed. Chassis manual not close so I'm guessing at the setting. As the fan selector is moved upward, it closes contact between two exposed copper fingers, providing 12V to the AC clutch. My bet is the problem lies here with a loose or worn component.
