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Jumping in here to let you '96 C4 owners know that I have a set of the HVAC vacuum lines, the one that go to the actuators in the dash, has the green block that bolts onto the HVAC Programmer....for the cost of shipping it.
Thanks for the picture. We were able to route the vacuum lines accordingly and now have a fully functional HVAC system. I will suggest to anyone attempting this to be prepared to remove the seat. Also, the filters on the solenoids were like goo, so we bought some material that was actually designed for house vents from Ace Hardware.
Old filter. They slide out for removal. Before pic. Vacuum line has deteriorated. Rerouted lines and ran them through the existing holes in the box. New filters.
Thanks for the picture. We were able to route the vacuum lines accordingly and now have a fully functional HVAC system. I will suggest to anyone attempting this to be prepared to remove the seat. Also, the filters on the solenoids were like goo, so we bought some material that was actually designed for house vents from Ace Hardware.
Rerouted lines and ran them through the existing holes in the box. New filters.
Mickster - Excellent info and pics, thanks for sharing. However, hard to tell how that bottom row of vacuum lines connect. Any chance you have a different angle of that to see the bottom row a little better? I'm sure its back in the car now, so no problem if not, as I can see it when I take mine out of course.
I'm planning to do this project on my 96 LT4 this Friday, so planning ahead in case my OEM bottom row has deteriorated too. Or, I might just do it to avoid it deteriorating. I even got the little filter stuff you noted as well. I'm hoping to just do this one time.....
Mickster - Excellent info and pics, thanks for sharing. However, hard to tell how that bottom row of vacuum lines connect. Any chance you have a different angle of that to see the bottom row a little better? I'm sure its back in the car now, so no problem if not, as I can see it when I take mine out of course.
I'm planning to do this project on my 96 LT4 this Friday, so planning ahead in case my OEM bottom row has deteriorated too. Or, I might just do it to avoid it deteriorating. I even got the little filter stuff you noted as well. I'm hoping to just do this one time.....
Well, I did this project to my 96 LT4 yesterday. Ended up doing it with the seat still in the car….if I ever have to do it again, think I’ll take the extra few mins to pull the seat out as everyone suggested. Not a difficult project overall but definitely a challenge due to where it is located. And the fact that GM did not have much slack in the vacuum lines coming into the back box didn’t help either.
I ended up cutting out the quick connect/disconnect block. Didn’t look like my hoses were clogged at that block but I’m sure it was a constricted area in the flow thru the hoses. I ended up going with 7/64 hose size, bought it at AutoZone. I had purchased two other sizes on Amazon and they were just too big, weren't tight enough on the hoses for my comfort level. I also removed the little filters and replaced them with new filter material as Mickster noted in his post. I didn’t have to remove that block where all the lines come in as it had not deteriorated, it looked really good and was not brittle.
Overall, it appears to function better. I’ll know more next week when I drive the car more than just idling to check it out. Here’s a few pics:
Finished product to re-install in car (after I add the cardboard cover of course). Block where vacuum hoses terminates looks great. New filter material installed. Removing the old, jacked up filters. They basically were goo and crumbled. Took the little covers off and basically scraped the filter material off with a small flathead and cleaned with alcohol wipes. Cleaned from old filter removal.
Last edited by TripleB5832; Sep 18, 2023 at 02:02 PM.
What a great thread. I recently cleaned the climate buttons on my '96 LT1 with pencil erasor and q-tip/alcohol, and all the buttons, fan speed, temp, etc work. I was still only getting air blowing out of the windshield defrost, so on to this vacuum hose issue. Everything in this thread was spot on, and I repaired mine using TripleB's method. I used $4 worth of clear PVC hose (see photo below). Took probably 6 hours, the worst part trying to get both hands under the compact dash to jam the tubing together. But everything works! Thanks everyone.
Well after around 3 or so days of trying to fix my "AIR" from only coming out of the windscreen demister, I've just become an A+ student & conquered this b1tch.
I first started with the dash module & fixed the buttons.
I then advanced to the HVAC programmer & replaced the flitters.
I then graduated to the vacuum side of things and re-piped the mother.
It now blows up, down or in ya face. I'm so happy.
It was definitely worth standing on my hand a couple of times throughout the ordeal and now that I've accomplished it, I wouldn't hesitate if I had to do it again.
For those thinking about fixing their own, I've done a quick 20-minute YouTube video that will guide you through to harmony.
