On the receipt the part is called a motor ( I would call it the heater blend door motor). I've also heard it called an actuator. It is a motor that moves the heater blend door to adjust the temp of the air that comes out of the heat/defrost. I'll try and describe what mine looks like. It is NOT round , or cylindrical like most electric motors are. It is somewhat square shaped, about 3" by 3" and 3/4" thick. Its case is a white-ish color, has a clip with a few wires, and there will be a driver shaft coming out the back side of it that will go into the slot that moves the blend door. The end of the driver shaft is about 1/4 " square. Actually 3 sides of the shaft are square and the fourth is rounded.
One thing I did was to check and make sure that the blend door was ok, and not jammed up or broken. So after I removed the old motor what I did was to take a 1/4" drive ratchet extension, place it in the slot and make sure the blend door moved freely. It does not turn very much. About 1/4 to 1/3 of a revolution.
When it works, the motor moves the driver shaft slowly.
Mine is located under the dash about in the center of the car.
Hope this helps.