Calibration of the system is simple, but a bit of a pain.
First, you need to remove the inner glove box, then look through the hole (the one closest to the center of the car in the dash board brace) to find the threaded air mix door actuator rod that is snapped into a white plastic retainer. Depending on what temperature your system is set at and what the temp is inside, it may be a little difficult to see. You can adjust your temp to try to see it better. While adjusting the temp, you should see the arm and conector travel back and forth as it adjuts the mix of hot and cold air. Once you have it located, you need to stick a flat bladed screwdriver into the hole and underneath the rod (not the connector) and "pop" the rod up, out of the white connector. The hole you want to look through will be the one closest to the driver'* side as shown in this pic.
This pic is looking through the hole, behind the glovebox that shows the airmix door actuator rod in place in the white connector that is attached to the airmix door to determine how much hot/cold air. There is small black plastic box that you can't see that drives that rod. While looking through the hole, adjust your temperature on the contol panel and observe what the rod does. It should move all the way to the passenger side for full heat, and all the way to the driver'* side for full cold. If it binds, pops, or clicks, and doesn't move or moves erratically, then the airmix actuator is broken.
Here is a drawing showing the airmix door actuator location. You can't get to it though the glove box. You have to go from underneath or take the dashboard off.
With the air mix door rod disconnected from the airmix actuator, the calibration procedure tells you to command "Full Hot" from your dash controller. This moves the "gears" in the actuator and the rod to the "Full Hot" position. With the door rod disconnected, your door is supposed to default to full heat (I suppose they designed it so those in the colder climates wouldn't ever freeze to death if the damn thing failed, but those of us in the warmer climes really don't think being baked to a crisp is a very enjoyable way to go, either). Anyways, snapping the rod onto the connector after both items are in the full hot position is what "calibrates" the system.