I am currently working on this same issue. My blend door is stuck, broken whatever but turning the dial to hot air starts this annoying knock AND NO HEAT. Considering avg. temp is 20° after dark, driving is miserable. Anyway, I've been searching EVERYWHERE, from YouT to Ford.com and not one offered any tangible information except hat it IS the (actuator) blend door, a common problem with Explorers apparently, nor a quick way to access it. The best way that I am discovering is that there is no easy way to access it. On my 2003 XLT the actuator is located on the driver's side just under the radio. Looking at the instrument panel it would be at about the height between the dials and radio.The problem is getting to it under the dashboard. Its location is near impossible to get to unless the dashboard is completely dismantled. Honestly, I don't see another way. Someone suggested going through the glove box and pulling a valve when you want heat. Huh? Another person suggested going through the radio slot, well that's just about the same process just to remove the radio and the actuator can't be removed, it's only to readjust the bar if it is dislocated off the gear. I need to replace the entire part. The knocking issue indicates that the blend door is stuck or broken inside the actuator, most likely the gear inside of it has lost some gear teeth, enough to prevent the bar from turning and so on. Anyway, to answer your question, you have to remove the lower dashboard. The reason I am on this website? Because I need help locating the screws and clips. One would think I should be able to remove the dashboard after removing 15 screws. Side note: each screw does have a number that coincides just under the screw hole. But, no where can I find the total amount of screws AND the numbers start over with each section. So I'm on a path thinking I've got them all when I discover that the path changed somewhere and I was counting the wrong screws. I assumed that going from passenger to driver the numbers increase and the last screw on the driver's side has the number 15. BUT there are 5 screws that I know of that also prevent removal. What I need to know is how many more are there or is there a diagram of screw and pin locations??? Sorry my reply didn't help you but maybe it helps to know you are not alone. Good luck and if you find any new info don't forget to publish it here.
