Ok so I have a puzzle on my hands, my heater in my explorer is not working! I have changed the thermostat, fluched the heater core and checked the blended door. When I turn on the heat air blows out of the vents like it should but its not hot. The car warms up like it should, and today it did get a little warm while I was driving down the road but as soon as I stopped at a red light it went back to being cold again. Does anyone know what could be going on that would cause this?? Your help is greatly appericated!