'68 Hot water valve
 

Which vac line from the heater temp control goes to the hot water valve under the hood (A/C models)?
I've already deleted the A/C but since I have the valve installed, I figured I'd use it...plus, I need to know what hose went to it originally so I can see if it's plugged, open or what.

I'd have posted this in the heating and cooling section but I know the '68 A/C and heat control head is a one year only deal and this is where the '68 guys hang out (all two or three of us).

Greg to my knowledge to 68s did not have the heater core shut valve I have this diagram for 1969 That's something I going to add, But this 1969 Tempest vacuum diagram doesn't make sense. Maybe it will help

Well, I was starting the wonder about it myself. I couldn't find reference to it anywhere, and yet the auto parts stores show the part number. Finally, I found a photo and reference to it in the Zazarine guide. It says it was used only on A/C models from '68 to '70 I believe.
Thanks for the diagram. I ran across it somewhere, earlier, and it didn't click for me either.
I know basically that it gets vacuum when A/C is on max but beyond that, I don't know anything..

I've already deleted the A/C so I think I'm just going to attach a manifold vacuum source to it in November and block it in March...lol