Is there any heat or is it restricted ?
I would flush the heater core with a garden hose.
You can do that with a Prestone kit (about $5.00) or take both heater
hoses off at the firewall, buy a section of heater hose at the hardware
store and get an adaptor to hook one end of the heater hose to a garden
hose. Pull the car on the street, hook the garden hose to it and let it
rip. That will clean it out and give you heat.
As far as the floor heat...The door to the floor is not operated by
vacuum, but by electric. You can see that if you open the glove
compartment and then push down on the part that lets the glove box
swing down beyond the stop. Start the car and change positions on the
air control while looking at the doors. The one to the far right is
only for full A/C. The one toward the middle, I believe, is the one
that opens the door to the floor. If it isn't moving, perhaps a fuse
blew, or the switch there needs to be replaced.