ever thing else checks out, but no heat coming out of any of the vents

Where is the blend door located on my truck and how would I go about replacing it. I was also told that it was the air duct accuator, where is that located and how is it replaced?

blend door is behind glove box under the dash new servo motor is about 40 bucks/ if its not switching to defrost vent floor ect. that one is under dash on drivers side next to ductwork but should be same motor