Ok so I've searched the forums and Google only to find out that my flashing 4hi and 4lo buttons (both flash then stop then flash again a few seconds later) is either the switch or a bad vacuum. Well I replaced to switch with a switch from another blazer of mine that I know works. Nothing. We traced the vacuums and looked for holes ect but found nothing. Actuator is good, also. When I press the 4hi or low, nothing happens, no noise no nothing. I've heard about the switch thing on the t-case being bad but it seems that when it's bad, there's no flashing lights associated with it. While the vehicle is running, however, I can hear a kind of sucking sound associated with a vacuum leak and it stop when you turn off the vehicle. Okay with that being said, my heat is stuck on haha. I replaced that bitch of a switch, too. No matter what position you have the temp, position selector or fan speed, it's always on heat and floor. I don't think it's stuck on the lowest fan speed, I think it's just blowing out because of the driving because you can't feel the heat when stopped. Maybe a fan or relay? Are both problems tied into a vacuum issue? If so, whereabouts is my issue? Behind the dash? Under the hood? I'm normally pretty good with these issues but I'm lost. Taking a multimeter to everything in the am. Thanks in advance!