I don't seem to have any vacuum to the servo unde the battery tray. Can someone give me an explanation as to where it begins on the engine and where it goes next,etc,etc.I need to follow the path and try to find where the problem is. My vehicle is a 95 blazer. thanx. wnk.

 

There might be a vacuum switch on the drivers side of the transfer case. It has three vacuum lines going to it. It is known to fail causing the loss of function for 4x4. One line on this switch goes to the canister your talking about. There is an updated switch ready at the dealer they fixed a problem with the seal cracking and sucking up transfer case fluid.