Vacuum check valves, 69 A/C

[Donald G.]

I see in the NCRS manual that two check valves are used on A/C cars but they are not shown on any publication I can find. No one seems to know just where they go or how they are connected in the system. Dr. Rebuild diagrams do not show them either.
Any help or photos appreciated.

[Chuck G.]

Re: Vacuum check valves, 69 A/C

Sorry I couldn't answer your question last week, Don.

This is the place to get the info.

Chuck

[Jeffrey S.]

Re: Vacuum check valves, 69 A/C

Don:
If you tell me what the check valves are for (vacuum, AIR, etc) I can post pictures from my '69 (small block) w/air. All the original check valves are still in place so it might be helpful to you.
Jeff

[Donald G.]

Re: Vacuum check valves, 69 A/C

Jeff:
They are vacuum check valves and go somewhere behind the distributor. They are metal, about one inch in diameter with one inlet and two outlets.
I need to know the hose colors for the connections to the second valve.
Thanks
Don

[Jeffrey S.]

Re: Vacuum check valves, 69 A/C

Don:
I believe the check valve you are referring to is fo the headlamp/windhield wiper door system. I believe there is only 1 of these and this is not particular to A/C cars but it is for all. All hoses are black.
Jeff

[Jeffrey S.]

Re: Vacuum check valves, 69 A/C

Don:
Page J267 (UPC 12, A8) of AIM shows check valve.
Jeff

[Donald G.]

Re: Vacuum check valves, 69 A/C

Jeff,
Thanks for the picture, good to see an original car. No one seems to know what the second valve is but if you look in the NCRS judging manual on page 71 (maybe 72, I don't have it in front of me) it states that there should be a filter, then a check valve, then on a/c cars only, another check valve. The second one is the one in question. We have asked several knowledgable folks and no one seems to know. Dr. Rebuild specualted that it may be a filter in the headlight washer sytem that looks very much like a vacuum check valve but that he had never seen a second one in the vacuum system.

Thanks!
Kent (Don's son)

[Jeffrey S.]

Re: Vacuum check valves, 69 A/C

Don:
I found the notation of a second check valve in the judging guide. I will check again tomorrow on my car but all I can say is that the filter, check valve, hoses and all fittings and clamps are original to the car. Even the filament tape is still there on many of the fittings (I've owned the car since 1971 so I know the history). I really don't remeber a second valve but will look again.
Jeff

[Grant W.]

Re: Vacuum check valves, 69 A/C

Hi Don
If you have the Vette vues Fact Book. I have the 3rd edition. It shows the white check valve that is off the intake Tee hose. And the metal one on the drivers side coming off some black hoses. Page 72 is a small block and page 79 and other pages shows a Big block. The 69 AIM page J 267 shows the metal check valve and the white plastic as to their postions. Also original white check valves has the raised AC logo on the outer perimiter of the check valve. Hope this helps.
Grant

[Donald G.]

Re: Vacuum check valves, 69 A/C

Grant,
The white plastic thing is a simple screen filter. The check valves are metal with one inlet and two outlets.
Don

[Jeffrey S.]

Re: Vacuum check valves, 69 A/C

Don:
I researched the Bizzoko book and found no reference anywhere to a second check valve. Actually, what would be the point of A/C cars having a different configuration than a non-A/C car? The vacuum system has nothing to do with A/C (except that A/C cars have a vacuum operated shut off valve for coolant going to the heater core which is absent on non-A/C cars). The white filter and check valve and actuators, etc. are for headlamp and wind. wiper doors which were on all cars. Maybe I'm wrong but I suspect that this is a mistake in the judging guide. I will go outside and look again at my '69 this afternoon and post again.
Jeff

[Jeffrey S.]

Re: Vacuum check valves, 69 A/C

Don:
I just traced my vacuum lines from the manifold source to the farthest headlight actuator and there is only check valve.
Jeff

[Donald G.]

Re: Vacuum check valves, 69 A/C

Jeff, thanks for looking. Some day we will track this down.
Cheers
Don