In the two years of restoring a truck a few items are overlooked and not tagged or remembered. In my case I am having an issue with the vacuum lines that run from the climate controls to the heater box. I have an 85 GM factory manual and there is a diagram that is less than wonderful. I have figured out all the lines except one. There is a black line without any stripe that is about a foot long. In the manual it shows it running to the area where the flapper rod is located. Unfortunately there is nothing to hook the line to. It appears there is a circular knockout, which is not knocked out, where a tube could be on different years or models. Is this a case where the same climate control unit and lines were used on several years and changes to the heater box has made this black line unnecessary? I may have to go to the junkyard to figure this one out. I have not been able to find a clear diagram to help me out.
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