Fairly recently, The dial that's used to switch where the air comes from the heating/ac unit has stopped working. It's able to switch the unit on and off, And the green "AC" light turns on and off depending on the location of the dial, But the actual air output is not affected. It seems to be coming out the front vents, as well as near the feet. I've just replaced the blower resistor, though this problem occurred prior to the aforementioned replacement.

Any possibilities with what may be wrong? I tried search but I don't exactly know what that dial-knobby-thing is called.
Thanks in advance.

Incase anyone's confused about which dial I'm talking about:

I do believe that's a cable operated knob going only by the way mine feels. I would say the cable came out of it's clip or possibly broke.

The cable operated one is the temperature. The different settings is a vacuum harness. You might pull it out and see if a seal has broken/come loose, etc.

I appreciate the quick replies. I'll pull it out tomorrow morning to check for any breaks in the seal. If I should find one, How would I go about repairing it? Simply replacing the seal? And assuming there is no break, how would I go about re-pressurizing(?) said seal.

Sorry for my ignorance... I'm clueless as to how this works.

That system is definitely vacuum actuated. There is a vacuum line that goes from the intake on the engine, through the firewall, and into the control. This is a rigid nylon line, and there is a rubber connector on it near the brake master cylinder. It may be black or grey in color. I would look under the hood first to make sure that this line is intact (not pinched, disconnected, or broken), and then follow it through where it comes in under the dash.

If it is broken somewhere, you can get some windshield washer tubing (rubber hose) that's the right diameter to fit over it to splice it back together. There are also other lines that go from the switch that operate each of the controls (air doors), so if the main one is intact, you may have to look elsewhere.

If you don't find a problem in the main line, try getting behind the switch assembly and disconnect the line. With the engine running, it should pull your finger tightly against the end of it from vacuum. As long as there's vacuum getting to that point, then the problem is likely beyond the switch. I haven't had the need to pull mine apart to that extent, but if necessary I can look in my manuals for more info if you need it.

Good luck,
John