4wd engagement

[revin_11]

hi i have just gotten my 96 lim back from repairs where the transfer case was overhauled and the 4wd engaging motor was replaced. i haven't had the 96 long but i thought that when it loses traction at the rear you should hear a clunk and the front wheels will engage? also during testing i was in auto and had the front left spinning and also the rear right, shouldn't trac control see this and put power to the other two wheels?
or maybe my car is still not fixed properly????? i have noticed the air con does not remain blowing at the face to long (5 secs) so perhaps i have a vacuum leak but that wouldn't affect the 4wd?

 

[Texplorer]

The reason only one rear and one front spin is probably because you have an open differential. If you had a Limited Slip in the rear both wheels would spin.
When in 4auto you are basically in 2wd until the rear slips and then the front engage.