On the driver side the windshield, dash and foot well are all cold, when I adjust the temperature under the foot well I can see the spindle cog is moving but not sure if it's opening the flap inside where the heater core is to change from hot to cold.There are a number of "doors" in the duct work for changing where the air comes out (windshield for defrost, footwell for heat, dash for cooling, etc.). Perhaps one of these doors is stuck and not moving. Unfortunately, they can be hard to get to.