I have read that this problem is most likely a vacuum problem, but I can't find any hose/vacuum ball problems. I think I'm at the point of just trying to find the diverter/air blender and somehow permanently fixing it in the "vent" position. Problem is, I can't locate the diverter by looking under the dash or behind the glove box with the door pulled down. Any suggestions? Thank you.

 

Welcome to the forum


Blend door is electric and is for hot/cold, it has nothing to do with the direction the air comes out, i.e. defrost or vent.

Vacuum controls the direction of the air, defrost is the default, so off or no vacuum = defrost selected.

Vacuum comes from the intake manifold, it goes to "the ball", a vacuum reservoir, it has a check valve like power brake booster does, so it holds a vacuum even when engine is off.
There will be a vacuum line from "the ball", that runs thru the firewall and comes out behind glove box usually a hard plastic line, they crack.

First thing is to find that vacuum line that runs thru the firewall, pull it off the vacuum reservoir.........and suck on it, lol, yes suck on it, if it holds vacuum then problem is in engine bay, "the ball" or hose to intake manifold.
If it doesn't hold pressure then problem is in that line going to firewall or inside the cab.
If possible have someone inside the cab while you BLOW thru that line, maybe they can hear the air escaping.

 

Good info and thank you for the reply.
I see a gray and a black vacuum line coming from the same area of the firewall, and another vacuum line coming from the intake area. My vacuum lines I think are incorrectly routed in that the intake one is attached to a fitting or sensor looking thing on the passenger side of the block toward the front of the engine (see pic). The two other lines, black and gray, coming from the firewall are attached to the ball. Are those routed correctly please? Thank you very much.

 

Doesn't sound right.
Grey line, from firewall, should go to Heat control valve on the heater hose by-pass
Black line, from firewall, is the vacuum source for vent control inside the cab so goes to Reservoir.
The other connection on Reservoir goes to intake manifold

But don't have a 2001 in front of me

Have a look here: https://www.ranger-forums.com/genera...m-line-140022/