Under my son's 1995 Blazer looking for a transmission leak and saw this up above the trans. Motor lopes a bit a idle, everything seems to work with the exception of funky positions on the HVAC vent settings.

Anyone have any ideas on this line? This is top of transmission on the drivers side, you can see the open line center of the pic.

 

I'm guessing it's a 4x4? Does 4WD work?

The HVAC and t case is both vacuum actuated. Any leaks will make them stuck on their default position.. Defrost and feet. These have a vacuum line that runs from the intake (vacuum source) to the t case, which has a 3 prong vacuum harness/ plug threaded into it. From that plug, there's a line that runs to the vacuum 4x4 actuator under the battery. The last larger line is a vent and should be zip tied to the transmission dipstick tube or thereabouts. The t case switch is known to leak and allow ATF from the t case to get sucked into the 4x4 actuator as well as the HVAC lines and actuators.. Makes a huge mess that for me at least entailed removing the dash and replacing the actuators and flushing the hard colored lines with a mild degreaser. Is there any ATF in the lines under the hood? The line in the photo looks bone dry so you may be fine...

5/32 line for the intake to t case and t case to 4x4 actuator. 7/32 line for the t case vent.

 

Yes 4x4 and yes, 4x4 works.

I will track down the other lines you mentioned and report back sometime this weekend. Thanks for the input.

 

The only vacuumn lines in that area are 4x4 lines. If 4x4 functions properly I would think it's the vent hose for the tranny. There is a vent tube that comes off the top center of the bellhousing

EDIT: whoops, just noticed dlundblad covered that already