The controls on the dash actuate vacuum pots, but are also cable controlled. Make sure your getting a good reliable source of vacuum to the inside of the car. If your still not getting any heat it might be the heater hose bypass valve for the A/C. They can sometimes get stuck. Pretty sure it is vacuum operated.
See if you can move the shut off lever by hand...it will be up under the dash, on the firewall, by the passenger side kick panel. You'll see the bypass valve from the engine compartment...just try and figure out where it is on the interior side of the firewall.
