Air Con Issues Magna Te Exec V6

HI :) This is my first time posting here so sorry if what i say makes no sense :)
I bought a 96 magna TE a few months ago and i have an air con issue. When i turn it on, it doesnt really come out the vents, it sort of comes out near my knees, and this doesnt change when i move the thing from feet to face position. i can feel where it is coming out and i think somethings missing.. either that or its stuck at the foot position...
any ideas?? thanks in advance.

After market stereo? Sounds like the vent selector cable has come off. If it is, it'll be in the drivers side of the dash, up underneath behind where the stereo goes.

thanks heaps for replying.
yes it is an aftermarket stereo.
is the cable reachable without taking the dash/console off....ie can you just reach up under the steering wheel area and put it back on?

There should be about 4-5 screws to undo the drivers side under dash area, one should be under a plastic clip on the right hand side, 3 or 4 should be under the bonnet release clip (you need to undo it as it covers the screws that hold the dash together) and one on the left hand side. Theres a couple of retaining clips that also hold the surround in on the top, if you wiggle these gently you should be able to get it off. If you have a screw driver (appropriate size head, I think its PH 2 but double check anyway) then its easy to get off.

Have a read of the car stereo install how to thats floating around here somewhere, and get an idea of where you're looking. Once you've found that it should be a large white lever arrangement under the dash, the cable goes onto that. Its not easy to replace as the cable doesn't like bending.

thanks heaps for that. i had the stereo installed professionally in july so i might give them a call first and see if theyll fix it. hopefully they should. otherwise i shall try and get my brother to have a look at it as i am totally hopeless when it comes to cars.
have a happy new year!