2000 Dodge Ram heater/defroster air direction selector

I can hear no clicking.

It's manual. There's a knob you turn. Top knob is where the air goes (def, floor, to occupants, both, etc), middle knob is fan power, bottom knob is how hot or cold.

I'll look/listen tomorrow. Is there a vacuum line going to the switch? Or where are they/it? Where do they come from under the hood. Maybe, if it's a lack of vacuum, I could follow the line/s and see if there's something worn, crimped, or broken.

And I'll look at this too, tomorrow.
Thanks,
Frank

OK. I'm back. I listened and could hear nothing as far as air goes. I even took the dash apart and unscrewed the control box. Looking behind it everything appeared to be hooked up and like new. I switched from one position to another and noted that something changed slightly. It appeared to be the amount of air being forced through a channel - not vacuum but exhaust from the fan. As if it were being deflected in another direction. While less air appeared to come from the defroster vent, nothing came out of the front vents. Does this help with your diagnosis?

Can you tell me where the vacuum pump is on my diesel? If I know that I can check the hose to see if it has a break/leak/bend in it.

I have no idea.

Where do you get to the door? From the inside, under the dash? Can I reach it without disassembling a lot?

On the passenger side, under the dash, all is enclosed in a number of black plastic containers that don't have any indication on how to open them. I did see, however, one small flat, round item with wires coming from it that looked like it could be a controller of some kind. It appeared to be something that I could remove from its base.

I hope you get the pictures I have taken.

From another angle

First pic larger

I have found another website while waiting for answers from you. In it it discusses a "blend door" problem that happens to Dodge trucks of my year. It also shows a fix. Would you tell me if this could be the problem and the solution. Please look at heatertreater. Net and look at the 98-02 Dodge Ram. The video shows what I believe to be the piece under the dash on the heater component covers.