2015 durango has not heat in the front

Your vehicle has 2 separate heater cores - one for the "main" heat up front, and the auxiliary one in the rear. You will want to check the physical inlet and outlet temperatures of the front heater core and see if maybe there is a restriction there, or other functional trouble. Further, if your front controls do not go from hot to cold and back, you could have an issue with the blend door and plenum itself, not just the actuator that you state you replaced. Also, wiring could be a concern.