What is this?!?

[Ryannn]

I have that thing, it doesnt go anywhere on mine either.

 

[cubewhiz]

that mystery hose is for your HVAC stuff, which in the pictures doesnt appear to be there at all.

your truck should have a "T" fitting/check valve thing that connects to manifold vac, the line coming out of the blower resistor harness, and a vacuum reservoir canister. that line youre inquiring about is the one for manifold vac. its supposed to loop up and to the passenger side, through that little black loom thing, and then towards the heater box area. ill get some pics tomorrow of the setup on my 89/2.9 if i remember.

That would be fantastic. I certainly don't see any of that.

 

[AllanD]

Well it kinda looks like its for supplying some vac operated part of the HVAC system. Only problem with that is that I can't think of any of those on an 89.

Really the only thing I can think of that even uses vacuum on the 2.9 is the EGR system, and you shouldn't have one unless it's a California emissions truck.

the recirculation "blend door" is vacuum operated on '89-up rangers

 

[cubewhiz]

the recirculation "blend door" is vacuum operated on '89-up rangers

What is that?

 

[Earl43P]

It is a door in the HVAC box that opens/closes dependent upon the temp setting.

I think default (no vacuum present) is full hot and summer is coming.

I looked at my 90, that hose looks like my cruise control servo supply.
The HVAC nipple is under that trans spacer, sitting on the cowl in this picture.