Windshield Wiper Vacuum Question

[Luv C3’s]

I have been chasing a non functioning windshield wiper issue and I have a couple of questions. I have tried to find a vacuum line drawing specific to my 72 but this is all I can find (Pic 1),the drawing says 1968 to 82 but is quite a bit different from what I have (pic 2) in the first drawing it shows a relay that I don’t have, the wiper door relay shown only has 3 lines on it and one of them is not connected to anything, I have a port interlock switch behind the cowl that’s not on the drawing and the wiper door actuator is plumbed differently.
My first question is does anyone have a vacuum line drawing for a 72, I have an AIM coming this week, would there be a vacuum drawing in there?
My second question is the port interlock switch behind the cowl (pic 3)only has 2 lines to it the third outlet is not connected to anything, should there be a vacuum line connected to the third outlet? And if so where does it go?

I really appreciate any help or advice you can give me getting the wipers going, I don’t want to be a pain with pestering you all with a bunch of questions, I am trying to do research before I ask but some things I just can’t find the answers to. I have gone through the dash and under the hood I am finding more and more things wrong, it seems the previous owner was quite a hack, so far I have come across a few cut off wires, the wiper solenoid hanging by the electrical connector with no vacuum lines connected to it, the ground wire pulled off the back of the Tach, the wiper door actuator rod nut missing and it looks like someone has tried to put a regular nut onto the reverse thread to join it to the actuator, and a lot of missing or mismatched screws, so I am trying to work my way through the issues.

Thanks again for any help

 

[C8 route66]

 

[Luv C3’s]

Thank you so much C8 Route 66 I really appreciate it

 

[C8 route66]

Hope this helps you sort things out.

cheers, John

 

[Norm07]

When I did my 71 the vacuum systems for the lights and wiper/wiper doors were one of the more challenging parts of the build. I had the same issue as you. I pretty well started from scratch. I followed the diagram Route 66 sent you. My problems were a bad headlight switch and a bad wiper door switch. It’s not a real complex system but it’s worth the time to read/watch as much as possible. I would also suggest going on to Corvette Forums and reading up on the wiper door switch. Test yours to make sure it works properly. There are vendors out there selling ones that do not work. I went through two of them before I realized this. I believe I ended up buying a working one from Wilcox, but unfortunately they are no more.

Your picture #3(thing with the red and white dot) is the Windshield Wiper door vacuum switch.
The upper hose connection on yours should have a hose attached that routes back out through the firewall just an inch or so in to the engine bay. It is wide open not attached to anything.

I would start with testing the vacuum tank to make sure it holds vacuum/doesn’t leak. Make sure you have that initial vacuum source hooked up. If you don’t have one already you should get a Mity Vac or something similar. It’s invaluable when testing the headlight and wiper actuators, the vacuum tank and the other components.

If you need any specific pictures etc let me know.
Steve

 

[Luv C3’s]

Thanks so much for all the good advice Norm07, I have spent the last couple of days watching a. Bunch of videos and reading everything I can find with regards to the vacuum system.
I did see a video about the bad switches and yes mine although looking fairly new was bad as well, and although the Drawing above and the AIM Manual shows the third vacuum hose from the switch going back through the firewall and terminating there, the grommet that the lines pass through only has two holes for the hoses.

I did go through the whole wiper and headlight system and tested every part even the ones for the headlights that I knew were working and it’s a good thing I did because the right headlight actuator did not have a good seal so along with the parts I ordered for the wipers I ordered new seals and dust boots for both headlights to try and alleviate any more trouble down the road.

Hopefully I will get a working switch Thanks again for the advice