1959 vacuum lines for heater

[David Greenburg]

The vacuum-powered air door for the heating system on my non-a/c '59 doesn't work, and I'm trying to sort out the vacuum lines.  The air door mechanism itself is fine, because if I connect the vacuum line from the manifold directly to the air door, the air door opens and the car becomes a sauna in no time.  The diagrams in the shop manual seem to refer to an a/c car and suggest that there are three lines and a total of 3 vacuum-operated controls.  My car appears to only have 2 lines.  One comes from the manifold, throught the firewall, to the heater control lever, and then there is a second line from the heater control to the vacuum unit for the air door on the firewall.  Does anyone know how many lines there should be coming off the heater control, and where each connects?  Using a mirror under the dash, I see 3 ports on the back of the heater control, even though there are only 2 lines that I can find, and one of those was disconnected.   Not much fun under that dashboard, but it is a whole lot nicer and more spacious than any of my newer cars.

[Dan Marinola]

Hi Dave, If I remember correctly,on non AC cars the center port was pluged and only the two outer ports were used to operate the air door. The reason the center is pluged is to prevent vacuum leaks. Hope this helps. Dan

[David Greenburg]

Dan:

Thanks. That helps explain why I've only got 2 hoses and gives me a starting point for my investigation.  I don't see a cap on one of the ports, which may be part of the problem.