The air conditioning system on my 280Z quit working recently so I took it into the shop. The unit had been flawless since the LS1 was installed in 2003/4 and had not even needed to be recharged.
I assumed that the system had finally leaked enough refrigerant that it needed to be recharged so agreed with the shop owner to update the refrigerant from R-12 to R-134. They did that and it still didn't work - the compressor wasn't engaging. After a little intelligent troubleshooting (with the help of the FSM section on AC I provided them) they determined that the microswitch in the dash that the select lever on my climate control system engages had failed. Rather than tearing into the dash and then trying to find the switch we went for what I considered an upgrade. They installed a separate AC on/off rocker switch on my console so that I can now engage the AC with the climate control system in the AC (recirculate), vent (fresh air) or defrost modes. Having experienced the issues with trying to defrost a windshield in a humid and warm environment this is a huge step forward. It now functions like modern car systems.