I always blow out the (after air blowout)diluted antifreeze because if the lines are blown, the slushy AF left in is easier to get out if I want to make a mid-winter trip. If they are full of antifreeze/water mix (and there is always some left behind)it is much more difficult and time consuming to defrost the system. I put a jug of my blown out AF in the freezer overnight and it wasn't slush but hard pink ice. I too have a large high volume shop air compressor right next to my RV shed so don't believe you can get it all with air.