Do these stupid things really need to be there? I took another trip at Christmas and the vents moved to defrost on a couple passes. Really? This is the third time chasing this over the years. I mean, what is the purpose of a stupid little plastic-gonna-fail-tomorrow-piece-of-junk check valves? Is it necessary for proper function? I read the one at the T was added by Dodge as a TSB. I would love to just throw these things out and have perfect vents every time for once. Any ideas?

 

Removing the check valve gives you the same state as having a failed check valve.

They're there to isolate and maintain vacuum in the system (keep it working) when the vacuum drops at the source (intake manifold) on acceleration.

That's why the term is "wild vents"... the vents open and close with the ever changing intake manifold vacuum, rather than maintaining their set position, working from the isolated vacuum reservoir.

 

Install a larger vacuum reservoir.

 

Are there better vents available? These dumb plastic things look like a toy. How about metal or aluminum ones? And where is the vacuum reservoir?

 

Vacuum reservoir hides under the cowl plastic, sorta in the middle there. Its in the well with the wiper mechanism and such.

You talking about the vents in the dash? So far as I know, no one makes anything better.

 

Sorry, no I meant valves. How about a metal check valve that will not fail so often?

 

Oh.

Not that I am aware of. There may be some generic check valve that would work though. Some Hot Rod companies may make them.... (Ididit perhaps?)

 

First of all, thank you all so much for this thread. It is by far the most comprehensive and helpful for this wild vents issue.

I have a '96 RAM 1500 2WD with the gas 5.2L V8. I had the usual problems when the vents would shift to defrost when accelerating. I tested the vacuum check valve and found it to be faulty. Bought a replacement (generic) at O'Reilly's and replaced the old valve as shown in the pic. While there I also bought an assortment pack of vacuum tube end caps and capped the broken line to the cruise control servo (I'll replace that line later).

I was quite surprised afterwards when I started up my truck I had no vent control whatsoever. All settings give the same defrost and partial foot vents. I checked for leaks and re-checked the direction of the check valve, which I believe I have right, to no avail. I'm stumped. Apart from tearing it apart and starting over has anyone any suggestions as to what may have happened to cause this?

Thanks in advance.






My check valve repair




The full vacuum lines view

 

Turn the check valve around, and see if things start working.

 

Thanks HeyYou! Yes indeed, that was it. Now have working vents, stable/no changing during acceleration, and nice cold A/C (it's 116F today)

So, for those that read this looking for a solution for their wild vents, the generic vacuum check valve is oriented with the thinner side of the disc facing away from the intake manifold.