Heater Problems

When I change the selector switch from defrost to the floor the air wether it's hot or cold is blowing out the front vents, can someone tell what the problem might be ?

bad vacuum hose, actuator, or selector switch, or it got disconnected in the engine bay. you need to check the hose in the bay to make sure it's still hooked up. then remove the lower dash and inspect the hoses and actuators.

if everything is hooked up and not leaking, then the selector is not working.