There is a lot of great information on these forums about how the Super Duty ESOF system works with the Pulse Vacuum Hubs (PVH). Diagnosing with where air comes out of the defrost and so on.

For those of you with newer trucks though, you should be aware that in 2011 they switched to Constant Vacuum Hubs (CVH). When I google pictures of the vacuum hublocks made before 2011 and compare it to the vacuum hublocks I have on my 2011 I can see no visual difference between the two other than like the service manual says, the new CVH hubs have a magenta dot (mine has a blue dot as well). The service manual says the old style will have a yellow dot but I suspect that is only true if the old style is a replacement that was manufactured after the new style was put into use.

Anyway, the vacuum system has been changed so diagnosing based upon defrost turning on all the time is not useful anymore.

The CVH hublocks will engage when exposed to vacuum and they will disengage when there is no longer vacuum.

I have searched a lot on these forums and have found nothing to indicate this so I figured I would put a thread on here so that others who search in the future will find a hint earlier on in their search.

The overall principle of the system is the same and all of the components are the same except the hublock and probably the routing of vacuum lines and the vacuum solenoid. You still need to have a good seal on the back side of the steering knuckle and just no vacuum leaks in general.

I'm on a bit of a time crunch so this isn't all that well composed but that's the jist of what I've learned over the last couple of days while working on my 2011 F350.