The way I do it is first empty the system of antifreeze and than flush the cooling system using Calgon and water. Trust me, it works. Gentle enough not to harm anything, and yet strong enough to remove any deposits inside the cooling system Hissong Kenworth uses this, and it works awesome. When that is done, and the system is rinsed out, then I remove the radiator and spray that and the condenser with a/c coil condenser cleaner, spraying the heck out of the whole thing.Everything. Any kind of cooler there.I let it sit for 10 minutes and rinse with the garden hose.It is amazing how much fuzz and junk collects there over a years time.The problem with rinsing the outside of the condenser and radiator while it is still in the van is that you cannot get to every area of each 100%, and the area between the radiator and the condenser is limited.While all of this is out of the van then I check all belt driven accessories and the belt, replacing as needed, while cleaning the engine as well.Then I will usually replace all of the hoses as well. This pretty much gets rid of any water left in the system from flushing.Then I use the proper coolant. This usually takes a Saturday to do, but so much worth the un-rushed time it takes.