Air vents blocked, or is it vacuum leak?

my heat and my AC only blow through my defroster and floor vents, what could the problem be? is it a vacuum leak?

most likely a vacuum leak. i was able to hear it in my truck and trace it to a spot behind a kick panel under the dash on the passenger side. see the grey vacuum line?

Yup, loss of vacuum to the HVAC control head.  Quite possibly could be caused by a faulty vacuum switch on the transfer case allowing transfer case fluid into the vacuum system...  Hope its not that, but I've seen it before.

thanks for the help, i should be on the road here soon, so when i get the new motor in ill be sure to check that out and see if thats the problem. i just have some down time right now and i was just trying to fix a few of the minor issues i had, thanks guys.

i had the almost same problem on my s-10 i had. it would blow fine till i got on the gas real hard and it would start coming through the defrost and floor, once i would back off it went back to normal