Cannot change air direction 2002 GP SE 3.1

2002 GP SE, 3.1, Dual Climate Controls, 50K, nearly perfect condition
Hi folks,
I need a little help w/a climate controls issue. The fan isn't the issue. The fan changes speed and seems to work fine at all speeds. Moving the heat selector on either side will cause the temp in the car to change, like it should. Heat works somewhat, AC cools the car, defrost eventually defrosts the windshield. The problem is that I can’t change the direction from floor to face or defrost at all. If I could, I know this would make the heat much more efficient The vanes or flaps or whatever seem to be stuck somewhere in limbo. Heat doesn’t seem to be fully directed toward any particular set of vents. I looked for any loose vacuum lines, but couldn’t find any. What I believe to be the vac feed off the engine is a black vac line located on the air intake assy very near the alternator. It looks fine, winds around a few guides and feeds along with the wiring harness into the cabin on the fuse block side. I took out the glove box and looked for any loose vac lines, they all looked fine. I also manually moved what I believe to be the vac actuator for the defrost vane. It had an red vac line attached. It seemed a little tight, but moved freely back into position when I let it go.
I tried searching the forum for this, but it’s a little difficult to describe, which is why I took so much space to explain it. Sorry.
I’m kinda at a loss as to how to proceed, and any help would be appreciated. It’s cold and getting colder and my better half drives this car mostly, so you know it’s moved up a few notches on the priority list. (-:
Thx

Are you 100% sure accessory vacuum to the HVAC system is good. I'd pull the black plastic vacuum line and feel for proper vacuum or hookup an automotive vacuum gauge. Engine must be running at idle. The vacuum line originates from the upper intake manifold and loops around by the battery and main engine compartment fuse box. By the battery is a coupler that can become disconnected.

I'm not 100% sure about the accessory vacuum. I'll check it out and let you know. Engine seems to idle properly. I'd think that I'd might have some loping or other symptom if I was losing vac. Thx for the help. I'll check the vac w/a guage on Monday and post what I find.

Checked for vac at the intake manifold (didn't want to break the connector near the battery) and had a good bit of suction. With the engine idling, when I took off the vac line at the intake, engine speed increases, and then decreased once I put the hose back on. Putting a little suction on the line going into the cabin, didn't seem like there was much on the other end (like it was leaking down). As I said, I'll get a gauge on Monday @ work and check it out.
Thx again.

Thanks for the feedback. I would test it. I ran a 3400 SFI V6 (similar) and I get the same idle change pulling the vacuum line off at the intake manifold. Interesting how the idle increases and the engine does not die. On my gauge (0-30 in hg) I get 16-17 in hg. If it is good at least to the cabin area there should be a vacuum distribution block by the blower motor where you can hookup the gauge.

The plastic vacuum line is subject to the elements (heat & cold) and may become brittle or have a small leak. Let us know what you find. Good luck.

Sorry for the extended delay. I've got 17 in hg at the manifold and definitely have some sort of leak. If I put a vac pump on the black plastic line, I can't get any vacuum to devlop. What's more, I almost hear the leak, I think. The engine starts to falter some when I remove the line from the manifold, and returns to normal idle when I plug it back on. I'd think a leak would cause rough idling all the time. Weird. The line winds around past the shock tower on the passenger side and under the battery before it disappears into the wiring harness and the harness goes into the cabin thru the firewall. I'm going to remove the glovebox this weekend and trace the leak down, and I'll post my findings. Hopefully, it won't take 3 months for me do do it this time. :uhoh:

I am having similar problems and I'm eager to see what you find! Thanks!

Hopefully, this weekend we'll know. I'll let you know as soon as I find the prob. I knew someone else must be having this issue.

I found the air leak. The vac line from comes from the manifold and snakes around the upper part of the firewall on the passenger's side, past the strut mount and then down past the radiator overflow tank and into the wiring harness sheath to go through the firewall into the interior. There is a rubber inline connector about 10 inches above the point where the vac line goes into the harness. I thought the connector would be the most likely place for a leak, but it was OK. The problem was a small nick 7" below the inline connector. It was difficult to see and felt mostly normal. I actually blew some pressurized air through the line and then ran my hand along the line until I found where it was escaping. I cut the line 1" below the nick in the line, plugged it into the online connector, and re-routed the line away from any heat or moving parts. Now, my interior controls work great.
Sorry for the extended delay. I hope this helps. Thanks to everyone for the input.