91 4x4, Vent, and Pass. Window problems

Alright, about 2 months ago, my 4 wheel drive started to fail every now and then. The more I tried to engage it, the less it wanted to cooperate. Now the 4 wheel drive doesnt engage at all. About the same time as the 4 wheel drive started to go, the vents began to fail as well. They would blow normally when i first got my blazer, then only when i was driving at high speeds, but now its nothing. And my passenger side window used to just barely roll down and now that doesnt even work at all! Could it be a bad vacuum pump? bad vacuum lines? or all seperate problems. Dont know if theyre linked at all. Thanks.

Let's see, the 4X4 and the vents are both vacuum operated so your answer is yes to two of three being related. As to the window, no it is not related.

Any idea of where to start the troubleshooting? Im not exactly sure where the vacuum lines are located. If im not mistaken, the vacuum pump is good because my cruise control works?

Any idea of where to start the troubleshooting? Im not exactly sure where the vacuum lines are located. If im not mistaken, the vacuum pump is good because my cruise control works?

There is no vacuum pump. Unless you have a diesel in that there Blazer. The vacuum is created in the intake manifold. Look for your Master Cylinder, behind it is the brake booster. There will be a large hose that is approximately the size of a heater hose, maybe a touch smaller. Follow that back to where it comes from, that is your source of Vacuum.

Exactly what engine do you have?

Ive got the 4.3L. Definatly not a diesel :)

Well i dont know about the first two in my 91 i know about that darn window. Mine never worked since i bought it and now im just gettin it taken in to get fixed as i needed to get a new door panel because prev owner destroyed it. am curious about the 4x4 if any has answers because mine is starting to act up.