2001 Dodge Ram, 5.2L, 4x4 Hi all. This is my first time posting. My truck vents stay on defrost vents only. I have researched and found that when this happens, it is most certainly a vacuum line problem. While tracing the vacuum lines for the HVAC system, I found that the main vacuum line from the engine intake connection to the HVAC was missing (most likely mice). My question is, how hard is it to get to the back of the dash and install a new vacuum line run like that of original spec? I have not been able to find a drawing of which colored vacuum lines go where in the interior, so through my own hand over hand tracking I believe the black tube that connects to the HVAC vent switch is the main line connection from the engine. Is that correct? Would it be better to bypass the original spec, and run a vacuum line from the engine intake connection directly to the HVAC vent switch? Any help would be greatly appreciated. I have heard horror stories of people replacing their dashes after they have cracked. My impression was that it is a nightmare to get the dash out.