my a/c and heater both blow through the top of my dash no matter what setting i have it on, the temp **** and blower speed still work but the other control doesn't. what's wrong?

 

Probably a vacuum leak. First place to check is the vacuum line that runs along the firewall right above the exhaust.

 

Yes, you most likely have a loss of vacuum. The way it was designed, if you ever lost vacuum which controls the A/C and heater vents, you would never lose defrost. Start at the source (vacuum pump) and work your way back towards the A/C system. I found once that my A/C came out of the defroster vents, this was a result of me doing maintenance in the engine compartment and knocking the vacuum hose off of the vacuum pump.

 

where is the vacuum pump located? where is the best place to get replacement (better than oem) lines and elbows to use?

 

The vacuum pump is just forward of the power steering pump. As for replacement lines and elbows, I would personally just use whatever the local NAPA or auto parts store sells. They all seem to be about the same.