This isn't even getting looks in the tech forum, so maybe my Prelude brothers/sisters might have some insight for me:

My compressor clutch isn't engauging. I've gone through the process discribed in the shop manual to troubleshoot the problem, and when I got to testing the compressor relay, I got some confusing evidence that it's the cause. When I hook power up to the a and b terminal, I can hear the relay click. But when I hook it up completely and measure the voltages, the wires carrying power into the relay show battery voltage. Likewise, the wire on the permanant circuit side shows battery voltage. The wire on the switched circuit side, though, shows zero voltage. So the click makes it seem like the relay is fine, the voltage doesn't. Does anyone have an opinion on this? BTW, everything after this step in the troubleshooting guide checks out for sure, so I'm really suspecting the relay, but need a second opinion.

 

Give some more details like year and model and so on

 

92 Prelude S with factory installed air conditioning, and if you're looking at a diagram the dead wire is the red wire that runs from the compressor clutch relay to the compressor. Everything else has 11.9 volts with the car off, 14 with it on.