Last winter there was no cabin heat. The rest of the engine cooling system works fine. The A/C works fine, turn the A/C on full blast and the SUV fells like a rolling refrigerator. I had the thermostat changed out and the heater core blown out. Still no cabin heat. There is no coolant leak anywhere, I have been watching. When I turn the temperature control from cool to heat I can hear the electric motor that moves the flap working. But I don't know if the flap is connected to the motor. How do I get at lease a view of the temperature flap to see if it is connected to the motor and moving? Is there something else that I missed.