The answer to the original question is a definite Yes. Do flush the evaporator, but don't use AC flush, use acetone. Thanks whunter. I'm glad I flushed mine, a lot of bad stuff came out. There wasn't much oil left in the system, but apparently most of what was there found its resting place in the evaporator. A good portion of those 8 UV dye applications ended up in the evaporator, too. The first five batches of acetone came out brown and nasty; there was some solid stuff there too.

I really don't understand what the deal is with that "AC flush&clean" liquid (made by Interdynamics, bought at O'Reilys). It's not an organic solvent, it's more like an oil. If your pour some on a piece of paper, it won't evaporate. After it's used to flush a hose, it remains in the hose, and subsequent blowing of air through the system doesn't remove the liquid from the hose completely. You blow air for minutes, and small droplets of liquid keep coming out. Acetone is really different in that regard: you blow it out with air, it comes out quick, and then it stop coming out. I reflushed the condensor with acetone, and that helped to get all that AC flush liquid out. Still, it's probably unsafe to use acetone on non-metal parts. It would seem like there should be some AC flush that actually evaporates cleanly and completely, like acetone, but doesn't destroy plastics, like acetone does.