1996 tahoe vent not working

[blkchev96]

i recently replaced the stereo and now the vents wont change from the floor but temperature and fan speed controls still work and i can hear a buzzing sound from underneath the dash when i try and change vent position any ideas?

[CENA]

Had a problem with my defrost not working on driver's side. Turns out the vent was broke. The service place did not have to tear apart the dash to fix it. Hope this helps!