Wife's car and big time snow here in NW Pa. 4HI light is on, front drive shaft spins but not the axles. No broken CV's. I believe the vacum actuator to be working if the 4HI light is on. I don't know where to look from here. Could the whole output assembly on top of the axle housing be bad? Does anyone have a pic of this assembly? Thanks for any help. Dan

 

This is most likely a faulty front axle vacuum actuator. The actuator itself is located up under the battery tray and is supplied with engine vacuum to engage the front axle. If the front axle is not engaged, then you will get no power to the front.

 

Some dummy(self) when changing out the spider in the intake, knocked the vacum line off the tit going into the hvac system. Now I cannot find where it hooks back up at. Blazer in question is a 1995. Anyone tell me exactly where that connection is, I've looked all over and I cannot find it.

 

YEs, look on the back side of the intake manifold on the passengers side. There is a little tube sticking out, feel for it, you may not be able to see it. Your vacuum hose attaches to it.

 

I know where that one is, I can't seem to find the one for the HVAC system. Another post said it was on the firewall, butI cnnot seem to find it. Thanks. Dan