First you have to remove the glove box to gain access to the plenum. Next, remove the actuator from the box. The actuator is a flat white box that sits on 4 clip posts on the top-left of the plenum. It has a wire harness coming out of it. To remove it take a flat screw driver and pry up the front first then put the screw driver under and towards the back to pop up the back. You will see a white pin coming out of the bottom of the actuator. The pin is "D" shaped. Turn the ignition on and move the heat control and you should see the pin rotate. If not, the actuator is bad or the terminals are corroded. If it does move, set the control to full heat and turn the blower on high. This will force the blend door into the heat position (it is very important to do this).

Take a small dentist mirror and a flashlight and look into the top of the box where the actuator pin goes in. You should see that the chamber is half missing. It should look like the drawing below:

I think they all break in the same spot. Mine was in the position as the one above. Remember you are looking through a mirror so it is a little difficult to determine the exact position. If yours looks like mine did drill your actuator pin in the same place I did. If not, try and gauge where yours will need to go. I had to drill mine four times before I got the right position. I drilled mine with a very small drill bit. If you are looking at the pin from it's bottom, this is where it should be drilled: (drill about 1/2 inch from the bottom)

After drilling the actuator pin hole, you will need something to put through it. I used an old drill bit that was the same size as the hole. Just cut it to length (you will want a little more than 1/8th inch on either side of the pin). Put the rod through the pin (it should be snug so that it doesn't fall out). Then try snapping the actuator back on the box. If the pin won't go in fully the rod might be in the wrong place. Try turning the blower on high again to make sure the door didn't move and try again. If it still won't go in you will have to re-drill the hole. If it does go in, try the heat controls. If they work, congratualtions! Now take the actuator back out and glue the rod in place and put the actuator back on. You just saved yourself $1000. If only the cold or heat works, then either the rod is in the wrong position and will need to be re-drilled, or the door itself is also broken.