So, I got stuck the other day, realized my 4 wheel drive didn't work. I was searching on youtube since I know the blazer 4 wheel drive runs on vacuum. I came across this video because, well, I was having hvac issues as well, but that never really bothered me. So I go to exactly where this guy shows in his video, and guess what, my vacuum line was split in half. I went and bought some line, used like 3 inches of line (between a T and straight connector that was already in line) and BAM! 4 wheel drive actuator vacuums tight, whereas before I had none. My HVAC now does the whole floor/windshield or the cab, so I still have an issue there, but I am not as worried as I was about the 4 wheel drive.


Quick Note: common issue if your 4-HI light won't stay lit, but, at best flashes.