97 explorer 4.0l SOHC vac questions | Ford Explorer Forums - Serious Explorations

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97 explorer 4.0l SOHC vac questions

Joined
February 10, 2017
Messages
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City, State
Las Vegas, NV
Year, Model & Trim Level
2000 ranger 3.0l flex
I’ve tried searching and haven’t found a very direct answer...having the vents in the car switching from dash to defrost when getting on the gas. Can’t find a broken vac line or anything for the life of me. Does someone know a direct spot that is usually the culprit for this so I could look more closely? Work has been crazy lately so I haven’t had any time to sit down and run through every single line and pull fender liners off just for fun, so was hoping someone could point me to what is the usual cause for this.

Any help would be appreciated
 



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It’s the hard vacuum lines that come from where the heater box is - the lines go to the reservoir ball and the water valve in some cases - the reason it goes to defrost is for safety
 






Unfortunately no, I don't know of any particular spot and if you can't see anything visually, I'd get a thin piece of hose and a cigar to see if I can find where smoke gets sucked in, or just start running new lines. Attached is the workshop manual pages showing the vac lines and some test procedures, but unfortunately only a diagram not physical routing locations.
 

Attachments

  • air-conditioning 412-00 Climate Control 1999 Workshop Manual.pdf
    2.6 MB · Views: 78






Isn’t that by design? My truck cuts vent airflow when I get on the throttle...
 






^ Not that I'm aware of. Some vehicles, don't remember about these, will cut off the A/C compressor at full throttle but shouldn't change which vents it comes out of. Granted, only time I'm at full throttle is in an emergency avoidance maneuver so I wouldn't notice the vents, too focused on whatever is causing full throttle.
 






My 99
The computer will cut the AC compressor at wot
The vacuum ball has a one way valve built into it to prevent the vents form changing
But only for for awhile
 






Well, ****. Looks like my truck has been broken for a while 😂
 






^ I'd just live with it until it gets worse, unless your fuel trims are unacceptably high.
 






I’ve tried searching and haven’t found a very direct answer...having the vents in the car switching from dash to defrost when getting on the gas. Can’t find a broken vac line or anything for the life of me. Does someone know a direct spot that is usually the culprit for this so I could look more closely? Work has been crazy lately so I haven’t had any time to sit down and run through every single line and pull fender liners off just for fun, so was hoping someone could point me to what is the usual cause for this.

Any help would be appreciated
Assuming that you have the nonEATC, The vaccum system on all of them is designed to default to defroster. Check to see if it happens with a particular setting or from all settings like heat/no heat/ac max. This isolates which section has the vaccum leak. And is the place to start. It is likely to be a hose/hardline. The dashpots are pretty reliable. There is a vacuum switch on the back side of the climate control panel that shifts the vaccum. I have seen these fail.
 






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