Well, I looked for leaks and realized that the expansion valve was covered with dye, and there was fresh dye in the evaporator case drain (which I believe came from the expansion valve leak). I redid those seals, vacuumed down to minus 25 (held there overnight) and tried to recharge.

I got about a pound and a half in, and the hub was spinning on the compressor, but I never got cold air. I gave up, put most of the car back together, and drove to the local dealer.

The tech evacuated it and charged it up completely using the high side port. He said that if you try to charge on the low side port, as I had done, it somehow screws up the valves in the compressor. It blew cold air, I paid them $141, and drove home.

Of course it was blowing warm air by the time I got home. The hub spins, and both gauges read about 110psi. No obvious bad leaks, though there seems to be some dye around a crimp connection on the new hose, which I will take a closer look at.

After three weekends of playing around with this, I am at the point where I need the car, so I'm going to put the thing back together. If I do have a leak, I pray it's in the engine compartment and not the evaporator, because it will be months before I may have a chance to tackle taking the interior apart again. I am putting new MB spongy drain hoses on the evaporator case, because I feel that they will soak up dye and make an evaporator leak easier to diagnose in the future, compared to a rubber hose.

Phil tells me that there's no coverage for labor on these parts, which makes me wish that I had tested the evaporator somehow when I got it, rather than risk so much time on an unproven part.