For most acrylics I go right to the sink ( I spray in the kitchen) and flush the brush with warm water, back flush, flush , backflush till the water is not tainted. Then I use alcohol, flush, backflush. Rinse with water. This includes Model Air. Softimes I use a drop of dish washing liquid. I've also made up airbrush cleaner. And there are generic brands of acrylic airbrush cleaner, not to mention Vallejo makes their own. I've never bought a brand name airbrush cleaner though and my Badger is over 45 years old and counting. Every few weeks I strip the needle out and maybe remove the nozzle. I can do that on my Badger and Paasche single action, my double action can be more fussy sometimes.
Once you get the main liquid out of the brush alcohol will cut the rest, it's just not good as a thinner in Vallejo. Lacquer thinner works as others said, stinks but works. That is what I use for enamel and lacquer paint jobs, cheap efficient.