I had the same problem and all it took was some electric tape (just for temp though). I checked the air lines and the green was, which is for 2h was vacuuming but the yellow for 4h and 4l was not working. After disconnecting the lines from the transfer case, I realized that air was flowing fine by blowing in each line with a straw. As I followed the lines, a buddy from www.jeapthrills.com told me to check the lines when it gets close to the battery because the corrosion hits the lines and then the lines crack. Sure enough, just by touching the lines to check them, two more cracked on top of the cracked yellow one. After miticulous electric taping, I was able to salvage the lines and next I know I not only fixed the lines but also my 4 wheel was working like a dream.
Check the line by the battery and look carefully!
Hope this helps
Squintz
Check the line by the battery and look carefully!
Hope this helps
Squintz