Hi All,

I have my 77 vette dash apart. I pulled out the passengers side dash, the center dash cluster and the 2 console side panels. I removed the drivers and passengers side ducts and took the center duct out. I noticed that on the back duct, that connects to the defrost has a space in-between of about 1/16 of an inch. I am thinking about duct taping it closed, so that there is no air leakage when I get the defroster working. (is there another way?)
I have a fan motor blowing. When I move the bottom slide the arm on the top of the heater box does move back and forth and the door opens and closes. The A/C opens at the bottom to let air out when I bring the top slide to Max or Reg and the vent vacuum works when I move the slide to it. When I move to defrost the vacuum box does not work and I am not getting any vacuum from the connected hose. I disconnected the hose and I connected a solid vacuum to it, it opened and closed allowing the door to send the air to the windshield. I replaced the hoses switch at the back of the main control. I also have a new kit of rubber vacuum lines awaiting for me to replace them. I did notice that the lines that I got from "T" are larger than the stock. The stock are small thin things. Should I cut the good old thin lines and put them into the new hose centers?
Now, what is my best way to trace all of these lines and to replace them? It seems that I am not getting vacuum to the defrost control. I am debating on using a tape, connecting an old hose to a new one and pulling each one through, then connecting them where they belong. Then use new wire ties to hold the vacuum lines together like they were. It is weird that all of the vacuum controls but the defrost are working with the dash control.
Is there any manual that deals with this? Or can I get a hand?

Thanks
Jack Miller
1977 C3

 

Here is a vacuum diagram , it might help. Click on supporting documentation.
http://willcoxcorvette.com/repairand...lp.php?hID=273
I never thought the tape on the defroster dust helped much. I under stand the C4 blower motor works well for added air.

 

Roger you defiantly the go to guy when it comes to pluming vacuum lines and wiring
Scott

 

Thanks!
With that and a B&W schematic I had I was able to do it. My hands are cut up. It was a bitch of a job.
Getting that dash back together was a nightmare.
Now I have to figure out why the head lamps are slow ay closing, any idea here?.
I cut the dried off ends of the 3 lines going to the manifold vacuum behind the carb. It helped a litle.

Thanks
Jack

 

Thanks. Believe it or not it's kinda fun for me.

 

Vacuum relay dying.