This is more on trying to find some type of diagram for vacuum lines on a 99 Dodge Ram 1500 before I get to replacing the top dash. I would like for this to be my last time dropping my dash. I found the line going in the firewall on the passenger side but not the second line. I do see a hole behind the motor in the firewall that I am thinking is the second line but sure? Everywhere else the line seems fine. I am wondering if they routed a line behind the vent housing under the dash? It's hard to see looking down through the top of the dash. I'm looking at being able to buy the top part from LMC here in the next month.
Seeing these lines are known to get hard and brittle. My thoughts are to replace all the lines while everything is open. I have rubber tubing for this. Has anyone been through this? Thanks

 

There is only one line going to the cab, Do you have good vacuum at that line? If not check valve may be bad. Check out the thread here on the subject.

 

I seem to have good vacuum and I have checked the check valves and they seem to be working. The line has a T- valve on the end so If there was only one line into the cab. I wonder what the other side of the T is for? I am sure once I drop the dash when I get a new top.The problem should reveal it's self. Thanks for the help.

 

There should be one that disappears under the cowl, that goes to the vacuum reservoir. That may be the other branch of the T.

 

I found the one you speak of. I hooked it up and no change. I seen a video where it was running by the ac hoses that go into the fire wall. I haven't had the time or light to get in there and see if maybe that what I'm missing or just there is a break further in? I will see what I can but once I get the top and do that install. I will be dropping the dash down where I can get more access. Thanks

 

Mine was broke right by where the underhood a/c line connected to the one going into the cab. It was RIGHT next to the line, so, darn near impossible to see. Certainly not at night.

 

That I will agree. It is a pain to mess with. Hopefully this weekend I can get in there as far as my hands can go and see if maybe something can be found and fixed. I will also pull the glove box to get some visual going on. I really don't think it's much of a fix but more finding it. lol