So I know that I have a vacuum issues because no matter what I have the vent selecter set to air will only come out of the defroster. I also am pretty sure I know where the vacuum leak is. The rubber vacuum lines for the locking hubs are old and cracked and are actually not connected to the front axle. My question is if I cap off the auto locking hub lines will that stop the vacuum leak enough so that I can once again use the vent selector? Or is there something else that I can do. Let me know what you think.