Frankly, I don't know how it works, other than the fact that it's not a switch, takes a regulated +5V supply and ground, and produces an output to the climate-control unit N22.

I need to dig out my climate-control diagnostic manual for another reason, and I'll try to remember to look for any test for this.

Did you put a gauge on the system? You should see at least 30psi on the idle system (and that's very low - should be higher) if it's warm enough for the AC to be needed.