The heater stopped working in my car. Switches and blower are fine. No heat.

What is your question?

I have a 2006 Torrent that the heater does not work. The blower fan and all the switches are fine. Airflow will change from vent to floor to defrosters. When i turn the temp knob to hot air, only cold comes out. Does not matter what setting the mode door is in. I have read that it could be the temperature door motor is bad and needs to be replaced. My mechanic has not done this. Can we do it in our garage.