[Rich72C10]

Well something has dawned on me thinking about the heater throughout the night and letting it sink in that the stock heater valve is normally opened (no vacuum needed to open it). When I cycle the dash controls and go into AC and back to Heat, I start to get heat at the floor again (sometimes it takes a few cycles).

@Stocker - I did some feel testing earlier (lines get hot / read 150+ via laser), which is why I thought I needed to flush the core out (did with just water, then CLR) and then moved on to seeing if I had air trapped (burping the radiator).

Perhaps something is going sideways inside this doodad that lets various amounts of water through but always enough to read a hot line going into heater core. Assuming O'Riley's is telling me the truth, I'll have one tomorrow late morning. I needed to use a $5 awards anyway before loosing it.