I have the defrost default problem so many have. I replaced the wheel well lines and did the hub re lube and it didn't work. I'm trying to figure out where the leak is so the first thing I did was take the lines off the solenoid and hook a vacuum gauge up to see if all was well up to there. The red line going in to the solenoid was getting plenty of vacuum and when i plugged that line the vents all worked as they should so the leak is down line from there. I hooked that side back up and put the gauge up to the side of the solenoid that goes out to the hubs and flipped the **** for 4 hi thinking the solenoid would then kick some vacuum out the other side, it didn't put out any at all. What is suppose to happen when you turn the 4wd **** as far as vaccume and the solenoid go? Thanks in advance. Eric

 

Well you know the vacum pump works. Check the lines all the way to each wheel. I know I didn't have to tell you that but mine was burned threw just below the battery on the passager side. Its a hard line but plastic. I guess when the dealer changed my batteries they spilled acid and it finnally eat threw the line. I cut it, replaced with rubber vacum line over the hard line and its great. Just my 2 cents, hope it helps. One more thing, you should have vacum at the lines you replaced in the wheel well if all other lines are good.
Chet

 

Plug the vac line that goes to the hubs. There is a 90° elbow connector where you can separate the line for plugging. If the HVAC venting works properly then one or both hubs have a vac leak. To determine if a hub has a leak reconnect the vac line up top and disconnect, at the hub, one hub vac line at a time and plug the vac line. Check the HVAC operatrion again. If it still defaults to defrost re-connect hub vac line and try plugging the other one. If HVAC doesn't default with a hub vac line plugged that is the hub with a leak. See this LINK for ESOF hub info. Pay attention to the Grampy_Jim quote in the grey box.

In some cases a leak will be caused by the deterioration of the vac hose at the hub. If it is cracked or dry rotted replace it with a piece of suitable vac hose between the hub and the connection to the hard line at the edge of the wheel well liner.

 

That solenoid should activate and pass vacuum for 30 seconds or so upon activation of the 4x4 switch. When I bought my truck, the solenoid was failed. I replaced it with an oem solenoid only to have it fail 6 months later. When it failed, it leaked. The vac pump ran continuously and the heater system defaulted to defrost. If you need a new solenoid your looking at $50.

 

I was told to replace the vacuum hubs with WARN manuals. Vacuum system to unreliable for my taste.

 

So if I replaced the vacuum hubs with warn manual locking hubs, does this mean I don't need the vacuum solenoid? What's the purpose of the vacuum solenoid?

 

To sum up the OP's question, not very well!
Jim & fat Monty

 

Thank you guys I'll try this tomorrow.

 

Cory - Correct. If you go with manual hubs you don't need any of the vac gear. If you do go this way, disconnect and plug the vac connection at the wheel to keep crap from getting in. Vac solenoid is simply a vac switch to the hub to engage and disengage the hub.

 

Am I reading this right? Vac into ESOF module and no vac out? ESOF module... that's what happened to mine and this is common.

 

Yes Tugly that's what's going on. I'll order an ESOF module since they're not too expensive anyway. Thanks

 

I dont mean to be off topic but if you get the warns manuel locking hubs and your eosf dosent work... When you install the warns will you still have to get out and lock the hubs to engauge the 4x4?
I turn my **** to 4hi or 4lo and nothing happens. Get out and lock the hubs in and 4x4 works. One hub is going bad it takes forever to unlock so im lookin at warns. If I get them will my knobwork or will I still have to get out?

 

Bakerbuilttracks I installed a set of warn locking hubs and plugged my vacuum lines going into my hubs cause one factory hub was leaking and other wouldnt stay engaged. Yes you will have to get out and lock your hubs in. installing the new hubs was easy and took me 20 minutes and didn't have to take the tires off.