There is one often over-looked vacuum line that goes through the firewall, just left of the computer wiring harness. Look for the plastic line connected on the windshield cowl. There is a vacuum line that is connected to a sideways turned "L" shaped rubber connector. That is attached to a yellowish connector and another vacuum hose with a black line. Follow the "L" shaped connector to the firewall (may have a yellowish color line).
The best way to replace this line is to go to the junkyard, locate the line, follow it to the inside of the car under the glove box. You can release the door of the glove box by opening the door and and pulling IN the rear tabs on either side, allowing the door to lower further. This gives you access to where the vacuum line is hiding, but more importantly, where it is connected.
Have someone pull, gently, on the tube from the engine firewall. Look for the moving tube. Close the glove box door. Feel for the gently moving line with your hand, by going under the dashboard, or use the flash light on your cell, and stick your head under the dash and locate the moving line. Note where it is connected, cause your car is set up the same way.
You or your friend can pull the vacuum line out from firewall side for purchase.
When you get home, before you go snatching the old line out, push the old line INTO the firewall. Put the skinny end of the new line from the junkyard, into where you just pushed the old one. Go inside, under the dashboard and find the old line and the new line you just pushed through. Pull out the old line where it is connected and replace with the new vacuum line.
This line was broken on my work Taurus, bout allowing the air to blow into the vents, just the windsheild. This was a safety regulation by the government calling for this default location. So of a vacuum line went out, windows would always be clear if there was snow, ice, or rain issues.