1996 Ford F250 a/c , heat not coming out of front vents

i tuned up my motor and as i was finishing, i snapped off a coffee straw sized red tube , about 6 inches in length, i believe was some vacuum line, i dont know. first ford i've ever owned, ever since then, heat or a/c does not come out the front vents, no matter what setting the climate control is set on. heat or a/c only comes out defrost area. what did i do? i tried to rig up another straw/tube with no results. did this little red tube attach somewhere else, why is it affecting my air vents flow? please help, summers coming and i tried the a/c but with it only coming out of defrost area, it does not work well . thanks