If I have the climate control set to my feet, it sounds like something "closes" when I shut the truck off.

It doesnt do it on any other selection...

Is there something that disengages?

Its not really loud or anything, just kinda the first time I noticed it.

 

Vacuum operated vent?? A guess...

 

Yes there is a shutter that closes the vents in the dash when you switch it to floor. It is vacuum operated so no vacuum pump spinning, no vent. I think it is spring loaded to close the floor off in most operations.

 

Would that close and make a sound when I shut off the truck?

 

In the absence of a vaccuum when you shut it off it defaults to the defroster vents...

 

It shouldn't close unless you have a vacuum leak somewhere. Easy way to find if you have a leak is to disconnect a vacuum hose under the hood after the truck sits for a few hours. You should hear/feel suction.
A truck without leaks will hold vacuum for days if not weeks.
Most common places for vacuum leaks on a 12 valve are in the area around the fuel filter where they accidentally get disconnected while changing the filter or under the battery where acid eats the line to the cruise control actuator.

 

With the truck running, if I have the dial to JUST FLOOR and switch it to FLOOR/DEFROST, I hear what sounds like a relay in the dash...

No other noises in any other position, truck on or when I shut it off...

But when I shut the truck off with the dial to JUST FLOOR it makes the "relay" sound...

I went out and pulled the line from the actuator on the cruise and heard something...

All lines are tight and connected...

If I shut the truck down and immediately pull a line from the vacuum I get nothing...

But I know its holding vac...

 

Check your trucks, do you hear anything when you do what I stated above?

It would REALLY help me out...

 

I'm going to have to disagree with you on this.

I seriously doubt the truck will hold vacuum for more than a second after you shut it down...

I had a gauge on every line on the truck and pulled at least 20 - 27"

And when I shut the truck down the vacuum went to 0...

I wonder if you are referring to something else?

 

I work on these trucks all the time, believe me if there are no leaks they will hold vacuum for days.

The relay click you hear could be the A/C as it comes on in defrost.

 

So if I have a gauge on the line and it reads 20 at idle, then I shut the truck off and it goes to 0.... how can I have a leak that bad when everything works?

Or does the system release the vacuum somewhere?

Are you saying the truck should hold 20?

 

The noise is the thing that closes the vents behind the Airbag thing by the shifter...

Everything holds vacuum except the line going to the 4wd system...

Is there a vent that releases the pressure on a 4x4 because the line going to the top of the trans has a white and green line, and the green line has a vent on a 90* elbow... the size of a dime...

Everything works...

I had the truck torn apart... I don't know what else to do.

 

Sounds like the problem is in the 4wd circuit.
Cracked hose, bad valve on the transfer case or at the actuator on the front axle. Try putting the transfer case in 4wd and see if the vacuum holds, may help in narrowing it down. The two lines going to the actuator take turns in which one is under vacuum depending on if you are in 4wd or not.

 

The actuator kind of spins in either direction very loosely when I touch it...

We are talking about the silver thing that the vacuum lines plug into, right?

It looks like there is a nut on the side of the actuator, and the actuator spins (not completely around) in place.

 

my last 3 dodges made noises like that. and when i lost a vacume line it would make the shuttter noise when it downshifted on acceleration! my vac line on the firewall next to the break booster was the culprit most of the time.

just fallow and look at all the lines and yoou should see it. if not i also double checked the fittings for secure seal. just my 2cents
good luck