Dodge Repair: heater control valve, heater control valve, upper radiator hose

Question
my heater was blowing out cold air when it was in the heat position. so I thought it might be the heater control valve or the thermostat. so I changed both of them including the upper radiator hose. the heater core is not leaking so I know that is ok. the heater when in the heat position is now blowing out hot hot air which is good early in the morning, however, now the dam thing won't blow out cold air when in the vent position. could the heater control valve be the wrong one? or could the heater/AC control assembly unit be bad? I am stumped... HELP!

Answer
I need to know what year, make and model we're dealing with here.

There's a possibility that you've got a blend door that is either stuck and not moving.  Suspect components would be the control head, the cable attatched to it or the blend door and where the cable attatches to it.  

I need more information before I can pull up information to help you out.
Doug