Winter maintenance, did hub cleaning and checking for free movement, drivers side hub has been bad for a while but always just leave that one locked and never had an issue with locking up, vents, nothing. Messed around with it when i was bored and noticed the nipple on the hub was completely blocked, free'd it up but still didn't fix the hub (Definitely leaky)

Now sometime a couple days later i have lost vent movement in the cab, and it wasn't right after the cleaning of the hub nipple. It's been a few days.

My vacuum pump wants to run 24/7 and the vents wont come off defrost, not that it doesn't warm up the cab but it is annoying to have something not work right.

I disconnected the 4wd solenoid and plugged the side of the reservoir, taking the 4wd leak out of the equation but still no change, pump wants to run and wont change the vents. When plugging the hold right off the pump itself, it shuts off immediately, which leads me to believe it works fine. and also when i isolate pump - reservoir the tank holds vacuum fine and pump turns off.

This means i have a leak somewhere between the reservoir and the vents? I checked the only spot i knew under the glove box but those 4 connections are good, won't come apart if i try.

Hose on the heater valve is connected and fine

Also when i have everything hooked up, my 4x4 still locks the one free auto hub i have working, which means it should work fine?

Where else would i have an issue with the vents?

 

Next check the little hose set that connects the pump to the tank and the line goes over to the 4by4 valve and the heater control. Plug ends and see if you get an intermittent pump shut off. It cpwhould shut off quickly and stay off, intermittent means a leak in a hose. Wiggling hose you can find where the cracks are. This one tears where it connects to the tank on the two bungs, it cracks and leaves intermittent issues., I have had to replace it. I am currently running only to the HVAC bops, others blocked off. If this checks out, the valves in the 4by4 control box that sends pulses is not working. It can be stuck open and that is where you are losing vacuum too.

 

I've taken the hose that connects the pump to tank off and plugged with finger, it stays off even with wiggling it around.

Even with the system not connected to the 4x4 solenoid and plugged off, the vents still are not working, and the pump is not turning off

 

It's the line to the vents. Plugged the line to 4x4 makes the pump run, it's not 4x4.
Disconnect tank to vent and see if it shuts off, if so, it's the line to vent, go down stream and test again.

Pump works, shuts off when up to pressure. Line to yank is good, same thing. Then work from tank to 4x4... sounds like (4x4 worked on one side) you have a leak on one side.

Now work the vents the same way. Tank to vent switch, switch to to blend door...

Plug the line results in pump off, go down stream and try again.

 

Here is the plumbing for you.




AC 1





AC 2 Valve





AC 3 EATC



Marry Christmas


Sean


6.0L Tech Folder

 

Sorry if someone covered this, but i got time this morning to go over it more, and decided to leave all hoses connected at just take the 4x4 solenoid out of the equation by disconnecting the vacuum from it and plugging them instead.

That seems to solve it, vent operation came back. So the solenoid is bad, must have sucked some crap up when i was messing around with it a few days ago.

Thanks for the help, and the diagram

 

Anytime.
Your Welcome.


Marry Christmas


Sean


6.0L Tech Folder

 

I have taken my 4by4 switch apart, the tiny rubber seals get dry and don't hold tight. I tried cleaning the rubber gunk off but no joy, bought a new one. On the passenger side hub, there is a hose joint at a bracket, mine pulls apart every year. I have it back together with small clamps on each side of the barb that connects the hose down from valve to the shorter hose into the hub. Despite this I am running with locked hubs this winter. I also may have a tank or other hose leak so I now am running direct from the pump to the HVAC.

 

I've tested every line of hose in there, all seem to be fine, but i will be replacing the lines that go to the hubs with new line routed where i want it (Above frame out of the elements) just to make stuff look a bit better.
Also will have a large amazon goodie list for xmas, just need to find space in the heated garage