Heater always seems to blow out vents

[Hummbusa]

I have been slowly working my way through my truck and keeping it on the road at the same time. Anyways I replaced the heater core earlier this year and could keep my cab plenty warm...now that it is warming up even when the heater knob is turned all the way to what should be the off position it still blows. I can turn it right 3 clicks but the last click kicks it to high I can tell that. Also in the manual it says to pull out the knob for heat. It seems to make no difference if knob is out or in? Any suggestions? Thanks