My question is I only have air coming out the defrost vents no matter the settings. I can hear a vac leak in the dash but cant find it someone please help.

 

my '97 has almost the exact same problem, only i don't hear a vacuum leak. judging by the pictures that someone took when he replaced his heater core, it's possible you'll have to remove the dash to find and fix the vacuum leak. have you been able to narrow it down to a certain section of the dash?

 

I have had no luck but it is a vacum leak. you cant hear it as well when the setting is on bi level.

 

i was wrong, there is a vacuum leak. it's very faint, but i can hear it on the passenger side of the vehicle. it's more audible near the floor and with the glovebox open (the relay cover is missing).

 

Post up what you did to fix it. Good luck.

 

Hopefully it's just behind the climate control switch. Mine has a habit of popping off where the vacuum hose comes through the drivers side firewall. I can't see where it is exactly and have to feel for it to put the hose back together.

 

well, i think i found the problem (or at least part of the problem):
http://magtec.rvglug.org/misc/blazer/greyvac.jpg

and here's where the line is apparently supposed to connect to (thanks shadowhawk):
http://www.treasureboards.com/blazer/core14.html


seemerollin, pull off the panel underneath the dash on the passenger side, it'll give you access to the grey and orange vacuum lines.


edit:
fixed - reconnected the grey vacuum line, no more vacuum leak and now the vents switch like they are supposed to. i had to fully recline the passenger seat and lay on my back with my head underneath the dash to do it.

http://magtec.rvglug.org/misc/blazer/greyvac2.jpg

 

A little hint... The glove box on the '95+ blazers will rotate to point straight at the floor. The catch can be lifted up and then just rotate the glovebox around until it points at the floor. WARNING - if there is anything in it, it'll end up on the floor. You should then be able to see the vacuum lines that are there at this time. No standing on your head...

Here's the link to the thread with some pictures:
https://blazerforum.com/fb.asp?m=5223

Kinda late for you now, but maybe it'll help someone else later.

 

that would've helped immensely, unfortunately the glovebox in my '97 isn't the same style. i tried to remove it before standing on my head. here's a picture of it with the door removed:
http://magtec.rvglug.org/misc/blazer/glovebox.jpg

and a shot of it with the door on:
http://magtec.rvglug.org/misc/blazer/interior2.jpg

 

Oh wow. Sorry for the mis-information... I could have sworn that a friends '96 had the same glove box orientation as mine, but I probably am mistaken. Thanks for clearing that up.

Well, I atleast can say that the '00+ will have this luxury.