The A/C blows fine, but does not come out of ANY vents. Even when I change the control to floor, defrost, max a/c, normal a/c/ or vent. You can hear it blowing behind the panel.

You can hear it blowing behind the panel, but nothing comes thru the vents.  If you continue to drive, the a/c will slowly start to come out of the vents again, OR, once you have turned off the ignition and start up again, the air is blowing....BUT, it will slowing stop coming coming out of the vents.