1980 450 SL
If it puts a load on the engine but doesn't spin the compressor it sounds like the compressor may need to be replaced. The clutch may start smoking if you leave it on.
If it's connected and closed there would be no power drop across the 2 wires. Need to check it to ground. What matters is the voltage at the clutch. There is a chain of events down stream to check.About what I figured!
shouldn't I get power out of one of those 2 connectors with my test light though?
This looks fairly complete. Has expansion valve no orifice is used. Check the condition of your hoses.