any help with this would be greatly appricated I do most of my own mechanic work can't afford to take it to someone so any help from here is Defently appricated only thing I have figured out is even though all lines are hooked up not getting any vaccum to the line that runs down to the switch on the t case

 

where does the vacuum stop sucking ? Do you have vacuum coming from the in fender vacuum ball ?...could that plastic valve be in backwards ?

 

How do u check for vaccum in the inner fender exactly I haven't checked that only replaced the line going to the nipple and took the check valve and jist put a t in it's place to see what would happen and nothing happened and my vents won't change either but mostly worried about the 4wd thanks for the reply

 

There has to be a line going to the vacuum canister as well as coming from it. Do you have vacuum at the line coming from the nipple ? if not you will have to search for the line to the canister to check for vacuum. I don't know where the canister feed line is , but there has to be one.....Hopefully removal of the fender will not be required.

 

Looking at the diagram on the previous page , the orb or canister is fed from the t-case switch .....do you have vacuum at that switch nipple ?

 

i haven't felt any vaccum at the nipple I have read many post saying that one line goes from the actuator down to the t case another one for engine vaccum the orb basically and one just to vent got all lines correct even tried bypassing the orb by just plugging the line off going to the nipple because my understanding it was just supposed to hold vaccum even when the vehical was off but didn't have any luck I ran a vaccum line straight to the diahfram that pulls the cable to engine vaccum and pressed it into 4wd and it worked excellent but that leaves other lines unhooked and would cause the diafram to be pulled constantly

 

Do you have vacuum or suction at the T-case switch?.... did you replace the t-case switch ?

 

i don't have any suction at the lines at the t-case and followed detailed diagram to hook them up right it is like the line coming from the intake is not pushing enough vaccum but inside the vehical sounds like a vaccum leak and pin pointed it to the hvac plug that goes into the back of the climate control it's like it isn't sealing all the way haven't had time nor do I really know what to do to fix that I really do appricate you trying to help me means alot ive been stomped on this and I haven't changed the switch didnt see a point considering no vaccum there

 

if the vacuum is leaking real bad at the heater controls , that could very well rob the 4x4 system of required vacuum . can you isolate the 4x4 by disconnecting the vacuum to the HVAC and work on 1 system at a time ? , I would put a vacuum gauge on the intake manifold to verify its got good vacuum as well.

 

so I got to messing around with my blazer last week was just about to give up and decided to start it up and crawl under it and I plugged the line off going to my canister and I heard hissing under the vehicle had vaccum but very little at all at the line coming from the t case vaccum switch but heard loud hissing and found a line had a major hole in it which was the main vacuum line that t's to go from the intake down to the switch replaced it and put it in 4wd nothing still I was about to bang my head then for giggles I pulled the vacuum switch and it was damaged the ball wouldnt move freely and when pushed all the way in would stick for a min I cleabed it and tried to free I up no good there plus it was scratched pretty deep in the ball and where it is spring loaded felt like the spring was damanged put a new switch in and bam I have 4wd again so when in doubt check your t case switched worked for me and was only $16 at my local part store and u guess it had it in stock because its a common issue hope this helps someone with the same issue