I have a 2003 expedition xlt with a 4.6 engine change the control panel for the a/c and heater but still blowing cold air for the heat anti- freeze is at the right level what is the problem

plugged heater core ? under the hood at the fire wall you should see two hoses run into the cabin , see if they are both warm , if ones hot and the other's cold the heater core may be plugged , if you can disconnect them and water or air won't go through easily that'll tell you

More likely a bad blend door actuator/ vacuum motor

Acuator blend door has stoped working part cost $27.. to install is a trial.. you.. I have the same problem, You must take off the dash.. the part is located to the left of the glove box.. rockauto.com has the part, but you must be handy to install or pay $400 - $600 labor