I have done alot of research and haven't found anything about the particular problem that I have been having.
1. a/c is defaulting to defrost.
2. 4x4 high works
3. 4x4 low doesn't work
4. If i switch the ESOF selector to 4x4 high the a/c will come out of the panel for about 30 seconds then back to defrost.
5. It seems as if the vacuum pump is running/blowing continuously
I have tried setting the hubs between auto and locked and it doesn't seem to matter. I am on the way to the auto parts store to get some new vacuum hose to run to the hubs.

I am mind boggled right now!!!! Any help is greatly appreciated.
Thanks

 

Just a guess but...
Sounds like the vac system is marginal, maybe a small leak somewhere. That 4-hi works implies you have enough vac to lock the hubs. The ESOF, as far as the vacuum system goes sees no difference between 4-hi and 4-low. I would be looking hard at the transfer case. Never been into mine, but I recall talk of engagement solenoids and such that can go out.

That it goes back to defrost sounds like you have a vac leak somehere. The vac signal to the ESOF is only active for 30-45 seconds. Sounds like you might have a leak on the vent control side?? Disconnect the ESOF line running to the hub at the vac solenoid, then plug the solenoid outlet. Basically you are elimiating the ESOF side allowing you to see if you have a leak on the other side of the system. The pump should stop after a couple minutes if things are tight. If it doesn't then you know you which side of the system to look for the leak on.

-Mike

 

One more thing, and hoepfully this is it, and if it is you would not be the first to forget, but... In order to active 4-lo, you need to be in neutral, with the brake on and the truck stopped (or less than a couple mph).

 

^^^^ this is your 4 low issue.


I got tired of messing w/ the hubs and just use mine like manual hubs. Plugged the line @ the resivior. Everything works fine.

 

Same here, at least temporarily. I had the default defrost problem to.. I traced it to a vacuum leak in my one hub. My vacuum pump never shut off.. I plugged the line at the reservoir as well & problem solved ( for the A/C at least.) I'm pretty sure its the seal on the hub, which i'll replace when I get around to fixing my inner axle seal thats leaking.. Of course, thats after I get my transmission issue solved. And my leaky UP Pipes. uggghh. does it ever end??? I wonder if I can talk for into letting me being a "test" driver for a new 2011 ???

 

in my experience it's the diaphram in the hub that leaks, I've taken several apart and found a small tear in them. not sure if it's replaceable, I know it's not easily replaceable. Might be in guzzles writeup on hub disassembly. After not being able to put together a servicable pair w/ 3 used sets, I gave up. It's been 4 years now and no problems, just have to get out and lock/unlock my hubs. I typically do it twice a year, lock in october and unlock in april.

 

Hey Rob, funny you posted this because after doing my monthly 4x4 engaugement to keep everything lubed as you will with these systems mine blew thru the vents this past friday. First thing I did was go to this site and searched because of all the ESOF threads. I knew what the problem was in general but just refreshed with the specifics. Anyways, I checked out my motor and that was good, checked some lines but not all, tomorrows project. Kidos are back to school tomorrow so I'll be able to get into it, I'll post up what I find, good luck on your end.

 

got the a/c problem fixed!!! I traced it to both of the vacuum hoses running to the hubs. Now for the 4x4 low problem!! Still have no 4x4 low?

 

Glad you got the high figured out. Did you check the switch on the transfer case? Found my problem, loose suction hoses behind the glove box, no more defrost mode.

 

what switch on the transfer case??

 

When you go into LOW, the vaccum locks the hubs but there is an electric motor/switch on the transfer case that is activated to pull it into low range. sometimes the connector gets dirty. Pull it and clean it then try again. SHould be sitting on the top of the t-case.

 

ok I will check it after work

 

Did you try 4lo in neutral w/ foot on the brake? That gets alot of people.