The locks on my 96 avant are ever so sloooow to lock. I did some searching and saw something to do with vacuum assisted locks. What is that all about? Can a bad vacuum lineon1 door affect all 5?

 

Yup, any leak will cause them to move slowly.

Usually there will be a stored code about it.

 

Iused my hand held OBDII scanner and there were no codes to report. I do hear the pump running under the back seat and also hear a motor or pump running in the back hatch (avant) I'm going to look under the seat for good vacuum connections, but I'm not sure if I can get at the rear door pump/motor.

 

The noise in the back door was the vacuum leak. The is a module that the vacuum line connects to and causes a linkage rod to lock or unlock the back hatch door. Around the rod where it comes out of the module is a rubber boot that must be needed to seal in the vacuum, it had a dry rot crack, thus lettling a place for the vacuum to leak. A carefull cleaning and some silicon rtv sealed it up. The locks lock much quicker and the vacuum pump runs for a second or 2. It was a pain to get too, but worth the time and effort.

 

you answered your own question although the locks are controlled electronically by the key fob the motor is controlled by a vacuum system ( not the best way ) but it works and newer cars are fully electronic and the vacuum is deleted, it took Audi/BMW/mercedes to work this one out