Hello everyone, I drive a second generation 1998 Dodge ram 2500 v8 5.9 gas . I’m trying to diagnose why my vents won’t work and I believe that I have a vacuum leak somewhere.So far I have the entire dash off including the dash frame. I have my entire air-conditioning line set disconnected, and the same with my heater core. I am not mechanically inclined but I’ve been using common sense and so far it has worked for me. I am on my way to taking out of the whole HVAC box.I am trying to find a new vacuum harness Or even a used one but I have had zero luck so any help guys?

 

Probably not going to find one..... best bet is to find the leaks, and splice the lines to eliminate them. Usually, it's the lines under the hood that get brittle with age, and break. There are also a couple check valves under the hood that can fail, and lead to odd behavior.

Welcome to DF!

 

Is there anyway to fabricate a new harness?

 

Sure, get the right tubing, or, just use regular rubber vacuum line, label it in whatever manner you care to, (I don't think it comes in colors??? aside from black.....)

If you don't already have one, download the service manual for your truck from here. Vacuum diagrams should be in there.

 

I’ve often seen a hole in the vacuum line where it chaffs through on the edge of the firewall opening.

I splice it with 1/8” rubber tube and silicone... then position the rubber at the firewall opening (figure it will take a lot longer to chaff through the thick rubber than the thin plastic line).

But if it’s all apart, might as well replace all the lines.
You might find heavy walled silicone tubing, if you want pretty colors.

 

Hey chrisce250, your location says your in Miramar? Down by San Diego?? If I am correct then there are two great pic a parts near Oceanside Been to them and they always got second gen dodge trucks, check them out you might find the harness you need


viperdave

 

A couple of times I have seen under the hood, where the vacuum line goes into the firewall, just to the passenger side, it can break due to it getting hard from heat. This will prevent the vacuum operated vents from working. It is hard to replace but heat shrink tubing can attach them together.

 

I fixed my vacuum problem by acquiring a harness from lqk in Davie florida( junkyard). I also saw in the junkyard how the vacuum harness was supposed to be hooked up so in the end I cut the ends of the broken vacuum harness lines and use a bigger thick silicone hose that was on the vacuum line from the junkyard to splice what I needed to back together then I went over the ends with a little Epoxy resin to guarantee the repair seal now the vacuum lines work and the vents operate. Upon realizing this one of the plastic elbow is coming down out of the vent doors broke connecting it to the vacuum actuator.