a/c not blowing out the main vent

Your heater/ac register controls are vacuum actuated. I would start under the hood and locate the vacuum supply coming from the firewall (right side above or near the black plastic heater case) and trace it to a "T". There will be a vacuum line to the intake manifold (supply), and a vacuum line to a vacuum canister or reservoir. There is also a check valve that allows the reservoir to take over in case of a low vacuum signal (like passing or pulling a hill). I work on Crown Victoria Police Interceptors (same car, different badge, more fun). Usually it's a vacuum supply concern - a broken line.

Ac not coming from ac vents

Don't know

You could try to see if the solenoids are actuating the control the flappers that change the direction of air flow there's a couple of them. They work off of the vacume system.

Most common cause is a vacuum check valve gone bad --located under the hood passenger side this is a unit about $70.00 can be easily changed with just nut drivers. (this is on a 2003 Mer. Grand Marquis.