Not sure which piece you're talking about. The receiver (also known as a dryer), condenser & compressor are the main parts of the A/C system. Another common failure point is the expansion valve which is in the heater core area. I wouldn't remove anything from the system and leave it open to the air unless you plan on replacing all of the o-rings. A/C systems don't like to be open.
That's possible although I've not known an evaporator in a Legend to go bad. I've seen plenty of expansion valves puke, though. Evaporator sub-assembly is P/N 0210-SP0-A02 @ $354.47 and the expansion valve is P/N 80220-SP0-J11 @ $97.63. The expansion valve can be replaced without taking out the dash but the evaporator can't, to my knowledge.
+1 ^ also if the leak was coming from the firewall side it could just be an o-ring on the connections. Otherwise I would recommend removing the blower assembly so you can actually see the expansion valve and its connections.
Do I need to remove the blower assembly to get to it? I'm utterly sure it is the o-ring. The compressor was also leaking; I replaced it's o-ring, and the leak stopped. My A/C was fine until the R-12 to R-134 conversion system. That's when it started falling apart. Anyway, I appreciate your inputs.
In the bottom picture above the shiny parts, are where your A/C lines hook up on the engine side of the firewall. Check to see if your leak is there. If not there then you will need to remove the blower assembly to get a view of the expansion valve.