Heat blowing cold air

the blend door doesn't do anything but change where the heat is directed. If you are without heat, you should check the coolant level, and if that is good, you may need a thermostat. It probably wouldn't hurt to flush the cooling system.

Your vehicle has a heater valve under the hood. Follow the hose on the top of the engine to the connection which allows hot water into the vehicle. It run off vacuum. Make sure it is functioning. On my 96 it is on the left side of the engine when facing it toward the back near the firewall. It is plastic and black.