Unless you are using 'Door and Window Builder' by Cadimage, the standard AC doors and windows cannot be opened for animation. It is perfectly feasible to code in this feature on your own doors, but the AC doors are so complex, with several layers of macros, that it is not worth the hassle.
Here are a couple of threads that describe the process if you want to go ahead -
http://archicad-talk.graphisoft.com/viewtopic.php?p=112867
http://archicad-talk.graphisoft.com/viewtopic.php?t=2751
Hope that helps!