Dash Temperature Control: Hot or Cold, no inbetween

Reading through it, it does appear to support what Doug has been saying, that the temp control knob just controls the flow of coolant through the heating core, not a blend door. That's really surprising to me, but it probably means that my system is working properly.

correct to some degree but the electronic control valve as I understand it should decrease or increase the amount of Hot coolant and therefore vary the temperature
mine seems to works like that as I can control heater temp output