Edited on 2015-02-13 12:24:13
Since the leak seemingly can't be found, might be wise to pull the round tubes off the side of the climate case and inspect the evaporator with a mirror and a refrigerant sniffer. The attached pic shows the LH side of the case. You can see the evaporator is visible through there. Getting there and inspecting does involve some contortion, but it can be done. You can do the same thing on the RH side, but usually looking at one side is sufficient. If the AC has not been operating for a while, the evap should be bone dry. If it looks even slightly damp, that is refrigerant oil and tells you there is a leak of some sort there.
As far as doing away with it all together, I'm not a fan of that route. The AC does need to be there for the fuel cooler. If you doubt us, just unplug your AC on a V12 and drive the car a few days. Then I dare ya to tell me you don't notice a difference in the way the car acts, runs and performs.
Cheers,
