[busboy4]

Hi,
regarding your vents, stuck in defrost is the default position for no vacuum - my experience is with '96 but I think it follows for yours too. It takes vaccuum to move the actuators to vent, floor etc. It you look above the accelerator you should see a vacuum "block" where several different colored tubes come together. You can unplug that and check there for vacuum. If it is the same as '96, the black tube comes from the engine and provides vacuum. It should be around 13 in/hg at that block with the engine running. If not, the leak is between there and the engine. If so, the leak is inside between there and or at the selector on the instrument panel.
Let me know if I can offer more help.