No air or heat will blow out

[ridgemer]

I have a 1996 Chevy Lumina 3.1 my air conditioning is cold, my heater is hot but it will only blow through the defrost and the floor. It does not matter what setting you have it on no air will come out any where else. The high/low switch is working in respect to the amount of air flow. Help please!!!!!!!!!1

[cadgear]

Under the glovebox is the blower, blower resistor module, vacuum-actuated modules, and the vacuum-electric solenoid module. I'm willing to bet the vacuum line going to one of the two vac-actuated modules is bad, unplugged, clogged, etc. Crawl under there and see what you can see.

[richtazz]

also check the vacuum supply under the hood, it connects at the throttle body, they are known to crack.

[hugo_sd]

I have the same problem with my 95 3.1 Lumina APV. Does anybody know where the vacuum line(s?) end under the hood. Normally the air would come out of the front vents but after a few minutes the air will switch to the defroster and floor vents. It seems that I loose vacuum over time. Any ideas?

Thanks,

Wolf

[Brndo]

I had the same problem in my 92 3.1L. It was a vacuum leak. Start with the vacuum reserve (black ball softball size under front left fender) from there follow the vacuum line looking for cracks or a break. Mine was broken at a 3 way intersection of the lines under the hood just past the battery. My cruise didn't work until I fixed it either. I have a post on here somewhere about that. I replaced the 3 way "T" that ran the cruise and the HVAC and that fixed it. Haynes was no help but there was a sticker by the fan shroud that had a basic diagram of the vacuum lines and that helped a little but it took several attempts to trace these lines and find the problem. I HATE vacuum line problems. Good luck.

[TexasGuy]

If you have any other comment on this, please post.

[Manny_boy]

Brndo hit the mark exactly, there is what appears to be a vacuum check valve right between the battery and the cruise control module, it's really only a vacuum tee (three way) - the Help section at your local parts retailer will have the three way you need to restore your blower functions - or just do what I did, get a couple from the J/Y.

[TexasGuy]

I have no idea where the cruise control module is. Would it be a big trouble to help me locate the damn thing. It is starts to become hot here and cold air blowing into the feet doesn't do much, I got to find the leak before I start to pass out from the heat.

Here is a picture to the only vacuum distribution block I found. It looks alright but it is on the other side passenger side of the engine. Probably not it.

Picture of the block: http://clickatus.com/thing.jpg

[jeffcoslacker]

Originally Posted by TexasGuy

I have no idea where the cruise control module is. Would it be a big trouble to help me locate the damn thing. It is starts to become hot here and cold air blowing into the feet doesn't do much, I got to find the leak before I start to pass out from the heat.

Here is a picture to the only vacuum distribution block I found. It looks alright but it is on the other side passenger side of the engine. Probably not it.

Picture of the block: http://clickatus.com/thing.jpg

What is the one with the yellow cap or whatever on the right side, is it sucking air? Looks weird. Can't tell what it is.

[TexasGuy]

Looks like a terminator for an unused port. Just a cap.

[jeffcoslacker]

Originally Posted by TexasGuy

Looks like a terminator for an unused port. Just a cap.

Since that's the main manifold vacuum supply tree, you should be able to follow the lines out from there and discover some other junctions and tee's. Any coming through the firewall are climate control related, make sure they aren't leaking. Look under the dash where they come through, and follow them to the plenum and blend controls.

[TexasGuy]

Happened so that vacuum was not a problem, seems like a bad contact (electrical) on some vacuum distribution block. Look at the pics, can you tell me what is this block? Seems that the flow of air will depend if I twist the electrical plug, meaning some bad contact. No wonder it was cutting off and starting again to blow on bumps.

So, what is that block?

Pics: http://www.clickatus.com/cont/

I disconnected the freaking block, took some blood and pain. Same as with wiper motor, bad contacts. Thing is an array of magnetic relays. Seems that I don't have a problem with the vacuum because when I disconnect the line after 5 or so minutes after the engine stopped running, I hear a strong suction sound, so the vacuum doesn't go anywhere even when it being stopped to produce.

EDIT: Also, I had recently a leaky heat core, I bypassed it, probably will change it this fall. Anyway, when antifreeze was leaking out to the floor through that plastic housing that holds it, some seals had foam like stripes that got unglued from hot antifreeze and now the air will also blow out of these seals since the foam like stripes are undone. Probably it also doesn't send the full pressure to the vents, should I change the core now?

[richtazz]

change the heater core, check the vacuum lines from the block to the individual vacuum valves under the dash to see if any are diconnected/cracked. IF any are disconnected, you're losing your vacuum there and none of them will work properly.