Man, WTF. People suck ass...
You can find that control unit new for around $160 if you shop a little. I'd avoid buying a used one unless they will let you try it on the spot to be sure it works, these are very commonly bad, and also frequently get damaged when someone removes the factory stereo and lets the antenna lead fall down onto the unprotected circuit board. And, the plastic these are made out of is like glass, so look closely for damaged tabs that hold it into the dash and also hold the gray connector on at the end.
OK, once you replace the A/C control...back to the vent position, most likely cause is gummed up linkages on the actuator. This is the one at the far left of the A/C box, just above the driver's side of the transmission hump:
Lay some newspaper down on your carpet to protect it, wash down the linkages with WD40, work them back and forth a little. You'll see that the flat metal parts are actually sliders. The factory lube gunks up and they quit working right. After that WD40 dissipates a bit, a small amount of white lithium grease might be a good addition.
Richard