heater problems

hi all ive got an 88 lesabrethat runs great except for the heater.it will only blow heat onto the floor.no defrost or vents.and the heat it does blow isnt very much.anyone have any ideas?

The first thing I would check is the vacuum source. I believe the doors that direct airflow are vacuum controlled. There should be a vacuum tee under hood, possibly close to firewall, check for vacuum with the engine running. I believe the cruise control gets vacuum from the same source. That may not be your problem, but, I would start there.