vents
- Thread starter RandallDyck
- Start date
RandallDyck
SDD Junior Member
appreciate your help guys, ill check that pump out
entropyjones
SDD Junior Member
I have a similar problem to the top. I also have a 2001 f350 with a 7.3.
In my case the dash a/c vents never work anymore. They were working yesterday then just abruptly stopped. The defrost vents still work and they still blow cold air.
As for the vacuum pump it turns on immediately when the key is turned to on with engine off.
Another issue is a few days ago my mechanic friend noticed that a vacuum line near the pump that seems to run itself under the engine was cut. He reattached the lines together with the plastic seal piece and things ran fine. Except my gas mileage got a little worse. That was several days before this new problem. The vacuum line he fiddled with does not connect to the vacuum pump itself. It originates at what looks like a solenoid or something of the kind NEAR the vacuum pump.
I'm not having any other issues at this time. Breaks working fine. Barely have to tap them to make the truck stop.
Truck is 4 wheel drive but with manual hubs also. In the cabin it just has a three way selector switch between 2wd, 4w low, and 4w high.
In my case the dash a/c vents never work anymore. They were working yesterday then just abruptly stopped. The defrost vents still work and they still blow cold air.
As for the vacuum pump it turns on immediately when the key is turned to on with engine off.
Another issue is a few days ago my mechanic friend noticed that a vacuum line near the pump that seems to run itself under the engine was cut. He reattached the lines together with the plastic seal piece and things ran fine. Except my gas mileage got a little worse. That was several days before this new problem. The vacuum line he fiddled with does not connect to the vacuum pump itself. It originates at what looks like a solenoid or something of the kind NEAR the vacuum pump.
I'm not having any other issues at this time. Breaks working fine. Barely have to tap them to make the truck stop.
Truck is 4 wheel drive but with manual hubs also. In the cabin it just has a three way selector switch between 2wd, 4w low, and 4w high.
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DaveBen
SDD Senior Member
Somebody added the manual hubs if it has the ESOF (Electric Shift On the Fly) switch. It will work like this, you just have to remember to LOCK in your hubs before shifting into 4Hi/Lo. By the way, 
Dave
Dave
entropyjones
SDD Junior Member
Somebody added the manual hubs if it has the ESOF (Electric Shift On the Fly) switch. It will work like this, you just have to remember to LOCK in your hubs before shifting into 4Hi/Lo. By the way,
Dave
I prefer the stuff usually. By the way I was fiddling with the truck today and when I locked the hubs and engaged the 4W for a bit without driving it and then disengaged it and switched back to 2w the dash vents started to work again.
I should have left it alone but like a dork I wanted to see if all was well so I stopped, locked the hubs, switched to 4W again and that killed the dash vents again. 4W will work but dash vents will not. I guess I dont have enough vacuum to run both?
DaveBen
SDD Senior Member
If you have ANY vacuum, you have enough. The vacuum pump works or it doesn't, no half way here. You have a vacuum leak in the 4WD vacuum lines somewhere. I would guess where the hub vacuum line attached near the frame.
Dave
Dave
entropyjones
SDD Junior Member
Hmmmm... The 4WD light comes on when I select 4low or 4high. How come that seems to work but the dash vents don't?
because that's got nothing to do with the vacuum system.
vacuum source starts here..
runs to here..
where it splits, and one line goes to the 4WD system, the other to the HVAC
and the HVAC line runs here.. (note the line to the rt hub in the top of the pic)
then around here..
behind here..
under here..
and over here..
look again back here and make sure these connectors haven't been pulled apart by someone wearing cockroach killers
runs to here..
where it splits, and one line goes to the 4WD system, the other to the HVAC
and the HVAC line runs here.. (note the line to the rt hub in the top of the pic)
then around here..
behind here..
under here..
and over here..
look again back here and make sure these connectors haven't been pulled apart by someone wearing cockroach killers
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entropyjones
SDD Junior Member
Wow thanks a lot for those awesome pictures! I could trace the line under the hood but on the pass side that area is all covered up with a plastic plate. I could easily take it off but it seems to do the job of making sure that bit you mentioned isn't kicked out.
Also I should add that very briefly for a few hours the other day the dash vents started working again. And when they did the 4W drive stopped working. As I began to fiddle with that some the 4W came back on and the dash vents went out.
I'm sorry if I am so thick about this issue. I'm used to working on computers trucks are pretty new to me. Thanks again for your patience and those awesome pictures!
Right above the vacuum reservoir where the two cables split off to the hvac and the 4W there is moisture accumulating. You can see it on the top of the vacuum rez. Sort of wet spots and there is another tiny little drip from vacuum lines under the truck along the pass side. Are those my vacuum leaks? At your vacuum source picture before the two lines split off there is moisture on top of the rez.
Also I should add that very briefly for a few hours the other day the dash vents started working again. And when they did the 4W drive stopped working. As I began to fiddle with that some the 4W came back on and the dash vents went out.
I'm sorry if I am so thick about this issue. I'm used to working on computers trucks are pretty new to me. Thanks again for your patience and those awesome pictures!
Right above the vacuum reservoir where the two cables split off to the hvac and the 4W there is moisture accumulating. You can see it on the top of the vacuum rez. Sort of wet spots and there is another tiny little drip from vacuum lines under the truck along the pass side. Are those my vacuum leaks? At your vacuum source picture before the two lines split off there is moisture on top of the rez.
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