98 s10 blazer - vacuum switch

[robinrag]

Well i have read the many posts about this vacuum switch and i'm still not certain what to do here.

it sounds like my problem is the vacuum switch on the t-case. the humming noise when i top the hill. it goes away when i switch it to 4-hi, etc.

what is the exact part name for the vac switch on the t-case, so i can get one from the parts house, or is it the firewall switch? i called a parts house the other day and the man wasn't sure. he thought it was the axel actuator. is that the switch or the actuator itself.

also can the 4wd be toatally disconnected so it won't try and engage until i get this fixed. someone else asked that question and i did not see an answer.

will pulling a fuse take care of that?

thanks so much if anyone minds straightening me out on this.

robinr

[robinrag]

Just tried pulling the ATC fuse, did a little road test on the big hill i hit right before the house; still hummed, only with the fuse out i couldn't shift into 4hi. Had to stop altogether until the clunk, then drove the last 1/2 mile home.

[alblogg]

The actuator is under your battery box. Check your vacuum lines running to this for cracks and dry rot also check the actuator to see if the diaphragm is damaged and leaking. Then follow the vacuum lines to the transfer case that is where your motor is that changes the transfer case. If all is well try this from an earlier post: