I have searched & I have found vacuum diagrams but too small for my old man blind eyes.
Anyway, our 98 Blazer 4x4 is slowly getting everything fixed & put into tip top shape I hope.
Anyway I have a couple of issues & would like any input anyone may have.
When on cruise pulling a hill sometimes the heater/A/C system goes into default & blows cold air out the A/C vents. Vacuum leak is most likely the cause I believe. The other issue is I can hear the transfer case switching from 2wd to 4hi & 4lo. But I don't believe my front end is engaging. I have a lot of 4x4 experience & it sure doesn't act like it is.
My question is could my vacuum leak be the same problem for both issues. Isn't there vacuum that activates a actuator for the front end?
Anyway I would like any help you guys have.
Thanks.

 

yes on both counts.
the vac actuator for the 4x is under the battery tray.
check the vac line running from just about the middle of the fire wall right at the top.
there is a vac module there where the line runs down to that actuator under battery.
i had this same problem once...the vac line dry rotted on me.

 

Thanks for your input. I was kind of hoping there was a possible connection. Most of the stuff I have found is just simple stuff that needed fixing. Like the wiper arm loose on the motor, vanity mirror lights disconnected inside the headliner, etc.
Thanks again I'll check the line there. I had lines on a 1997 dry rot to the T/C before but never had any front axle issues on my 97 Blazer 4x4