dirkpitt77:
I use Model Master Acryls almost exclusively, so for an airbrush cleaner I use Windex With Ammonia. You can buy a nice big bottle of generic windex with ammonia for cheap, and it lasts forever. On occasion mine will get a bit of buildup too, so in that case I'll drip a little lacquer thinner through it til it's clean again.
dirkpitt77: you may already know since you've been using windex all along, but be very careful with letting ammonia sit in your AB. ammonia has the ability to etch brass, a large component of most airbrushes, and can ruin it if not careful. I too use it for future, acrylics, etc but always run a cup full of clean water afterwards.