When I first turn the key to the "on" position, I hear 4-5 loud clicks under the dash, right above the steering column. It's clicking hard enough I can see dust fly up on the dash and feel it in the steering wheel. I set the A/C to OFF thinking it might be a diverter door and it still does it.
It is a manual tilt steering column. What is up under there with moving, motorized parts?

 

Now pressing the button on the shifter engages something under there that I can feel in the steering wheel, but not on the dash, and it's a moving part because with the truck off, I only hear a relay and no solenoid movement. (or what I assume is a solenoid)

Just by chance it's that, maybe hold the shifter switch in when you turn the key to ON.

I guess if that switch is real close to making, maybe it would do that? Probably not. Cause if it's like mine, you'd hear the relay with the key OFF. If you hear nothing while the truck is off, I guess it might just be a "forget about it" until something doesn't work.

I tried the same thing on mine in different configurations and it's all quiet.

 

You're hearing the steering column lock activate. Normally, you won't hear it, so maybe it's getting worn some and getting sloppy

 

I did some more testing. It is definitely related to the climate control system. I have dual zone plus rear climate control. Hot/cold selections for any zone make no clicking noise so I'm thinking that rules out the blend door actuators. I can consistently make it click when I switch the system output from defrost/vents/floor. It cycles between defrost and floor, vents, vents and floor, floor only, then back to defrost and floor. It only clicks when moving from defrost and floor to vents. That seems to me to mean that when it is trying to close the defrost output, it clicks. So the actuator on that gate is what should be replaced.

Unfortunately rockauto doesn't have that part listed. Can anyone tell me if that is a dealer only part or if all the actuators work interchangably like the blend door actuators?

Thanks.

 

Fixed it! Thanks to some info from expeditionforum.com.

It is a 'mode door' that changes where the air flows, as opposed to a 'blend door' that changes the temp. The mode door that went bad on mine was on the left side of the plenum, next to the accelerator. I removed three 13mm bolts from the accelerator and pulled it out of the way. The mode door actuator was then easily accessible. Two 8mm bolts later, I had it in my hand. Replaced with YH1881 motorcraft part from Rockauto ($24.79). It wasn't listed under my vehicle. But it is the same actuator as used for the blend doors.

I took the top off the old one and it had a tooth broken off the gear that the spline shaft is made onto. Maybe I can repurpose it for a project with an ESP32 and motor control somewhere.