Vacuum Problem
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Lead Driver
Joined: Jul 2005
Posts: 5,967
Likes: 7
From: Eccles, WV
Vacuum Problem
Truck would not shift into 4X4 mode. I noticed that the air conditioning had changed to the default of defroster. It returned back to normal after about 10 minutes, but I have not been able to check the 4X4 mode (danged back surgery).
OK gang, give me some ideas at what I am looking for. First thing is where is the vacuum pump at?
OK gang, give me some ideas at what I am looking for. First thing is where is the vacuum pump at?
Not a liberal...
Joined: Jul 2006
Posts: 6,635
Likes: 4
From: Cut & Shoot, Texas
It's those damn yellow o-rings in the hubs. I don't care what anyone says, the ESOF system is a POS. I replaced EVERYTHING two months ago and it all worked fine. Engaged the 4x4 yesterday and I'm right back to where I was.
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
Hey Paul. In case you missed the earlier thread, I stumbled across some goodies. It might come in handy if you've got the patience to learn how they organized it. 2001 Workshop Manual.
I've got a 2wd, so I won't be of much use to your current problem.
I've got a 2wd, so I won't be of much use to your current problem.
Hook it, I'll pull it.
Joined: May 2007
Posts: 15,037
Likes: 4
From: Grand Lake, La.
Paul, unplug this elect. connection, then try again, If it goes to defrost, it's not your hubs. This solenoid allows the vacuum to go to the front hubs. If you don't have vacuum going to the front hubs and you still have the air going to the defrost, thats a different problem. Here is a pic of what you need to unplug.
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Lead Driver
Joined: Mar 2000
Posts: 9,359
Likes: 1
From: Hampstead, NC
This sound very similar to a problem that has come up recently with my truck, minus the hubs, since I have Mile Marker manual hubs instead of the stock ones. The heater is stuck on defrost(default setting), it won't chance to vent, heat(floor) nothing. The vacuum pump is running which narrows it down to a broken line somewhere.
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Of the next Riffraff East
Joined: Oct 2004
Posts: 8,679
Likes: 2
From: Concord NC
Rick, switching the ESOF is the same thing. If it only defaults to defrost when the ESOF is switched, the it is somewhere between the solenoid and the O-Rings Scott mentioned.
Mike, if yours is in defrost all the time, yours is a leak or a bad vacuum. Just because you hear it running, doesn't mean it working. Good luck
Mike, if yours is in defrost all the time, yours is a leak or a bad vacuum. Just because you hear it running, doesn't mean it working. Good luck
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Lead Driver
Joined: Jul 2005
Posts: 5,967
Likes: 7
From: Eccles, WV
Now this danged thing is driving me crazy. Truck to shop, on lift, checked all hoses and linkages. Mechanic in seat. starts truck with me and another mechanic underneath. I hear the clunk as it is shifted into 4X4, hear the danged hubs lock, no vacuum leaks, seals are tight. Makes you wanna cuss!
Truck is just like a woman, always messing with us guys minds. No wonder we always call them girls.
Anybody got any ideas? My mechanic told me to stop doing drugs and driving in the mud, then showed me out the shop....... LOL
Truck is just like a woman, always messing with us guys minds. No wonder we always call them girls.
Anybody got any ideas? My mechanic told me to stop doing drugs and driving in the mud, then showed me out the shop....... LOL
Of the next Riffraff East
Joined: Oct 2004
Posts: 8,679
Likes: 2
From: Concord NC
Yes, it is electric. You should be able to hear it run for a few seconds after you turn you key on. Have someone in the cab while you are under the hood on passenger side. Have them turn key on, don't start, and you should hear it run. If it runs contantly, it has a leak, if it don't run, check for power, if it has power to it, replace pump, if not, find bad fuse or relay.
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Lead Driver
Joined: Jul 2005
Posts: 5,967
Likes: 7
From: Eccles, WV
Now I am going searching. There are not that many lines, but 8 years of wear may have cracked one. That A/C to Defrost fault sure has me puzzled. It did it three times on Sunday. No more since. One thing I have noticed is that the A/c is a lot colder now. Maybe there was a hang somewhere and it took the pounding I had to give it Sunday to free it up. A/C will now run you out of the cab. 
Of the next Riffraff East
Joined: Oct 2004
Posts: 8,679
Likes: 2
From: Concord NC
So, the pump is running? Does the AC default to defrost with no warning and with no help from you? Does it do it on regular AC are just Max? Sorry for all the questions and no answers, but it does sound like a small leak and the vacuum canister is leaking down, allowing the defrost to blow until the vacuum pump build enough vacuum to close it again. The added cooling you feel could be from the vacuum not opening one of the vent doors.