HHAAAA!!!!! Got heat ! ! First in garage without water I just used that posted tool on Amazon, and just blew air, through suggested return. Out came sounded like a glob and water.
Couldn't really tell, landed in a container with coolant(water). Then backed out where I have hose and did another half dozen "flushes". I have low flow from hose, let it feed return
a few seconds, then hit the air. What I saw coming out appeared to be WAY more than
what would flow through a mostly blocked heater core. Coolant temp 125 and I could feel some warm through vents. About what I had lately fully warm. Then at 162, very warm.
Yessss!