Good afternoon you guys, I am hooking up the Factory A/C and heater on my 71 SS 454, my issue is there is only one vacuum hose coming thru the firewall which I believe goes to the vacuum ball, all the doors operate correctly when the vacuum hose is connected to engine vacuum, what I don't see is a vacuum hose for the heater control valve to stop the flow of coolant to the heater core. the vacuum diagram I see online shows 3 vacuum hoses coming from the bottom side of the HVAC controller, mine only has 2 vacuum hoses.
Am I missing something? I would think there would be a vacuum hose going to the heater control valve from the HVAC control.