I finally got around to taking out my evaporator core. Surely enough, the evaporator casing has a bunch of the with powder in it. I didn't see an obvious place where there would be a leak, though. When it was first suggested in the post 6 months or so, I put som stop leak in it, but it still blows the flakes out every time I turn the air on.

Is there a way to fix it with solder? What's a good way to find the leak? Water and pressure?

Hot Rod Air doesn't even seem to be in business anymore, as their site doesn't even come up, so I don't even know how I would get a replacement.