my heater blows cold air... on 2004 Chevrolet Impala

when i use the heater or even the front window defrost, it blows cold air. it's really getting on my nerves bc i can't see out of the window in the mornings! any suggestions?

Is the air temp cold on both the drivers and passenger sides? If so then I would suspect poor coolant flow through the heater core. The hoses near the fire wall in the engine compartment should both be warm when the engine is warm. If only one hose is warm then there is no flow. If both hoses are warm then I would suspect a fault with one or both of the temperature door actuators behind the dash.