Changed the coolant last evening and refilled with no issues. Test run and topped off. However, now heat is non-exsistant when the temp knob is in the cold position up to 78 and once you go past 78, very hot. Checked heater control valve and arm is closed with knob in cold position and when incremented 2 degrees at a time, arm will not move/open until past 78 and then it opens all the way. I would think that each 2 degree step would result in valve moving a bit. Pulled vaccum line off valve and measured from there with same results. Does this mean the valve is bad or control panel is not producing the right vaccum??