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vent controls don't work when accelerating... where's my vacuum problem? (ea82T)


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so I've noticed that my vent controls don't usually work when I'm accelerating... they usually work fine when I'm at idle or decelerating... obviously there's a vacuum leak somewhere in the line that keep the pressure up to direct air flow... when accelerating it doesn't matter what vent I select it always comes out of the dash vents...

 

so where's the line that feeds the vacuum for my vent controls?

 

it sure would be nice to have my defroster available all the time... (:

 

thanks!

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Had the same problem on my 86 t wagon, turned out to be the control head in my case, the valving was all messed up inside.

The vaccum line comes off of the intake to the pass side, heads straight for the cruise control pump then heads next to the strut mount and goes to the little cloudy white canister by the firewall pass side from here I can't remember where is goes. Also check the one way valves along the way, on my 86 there was one maybe 2 foot before the canister.

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There is a whilte cannister mounted to the right hand side of the firewall, engine side, your left looking back down the car with the hood up, that has 2 vacuum lines hooked up to it. This cannister's job is to keep vacuum while the manifold is in a low vacuum state, such as acceleration. Just pick another cannister up from a junk car and swap it in, I think it may fix the problem. But then again I may be wrong. Good luck.

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  • 3 weeks later...

I snagged the white canister off a loyale and it's still having the same problem... the canister seems to be holding air, at least it releases pressure when I take off the vacuum lines...

 

anybody have a clear picture of what my vacuum hose configuration should be? I have only one of those "vacuum" valves in the line coming off the intake... it seems like there should be one before the white canister or something...

 

here's a large pic of my vacuum system highlighted... the cruise is the blue line... tell me if there's something obviously missing... http://easilyamused.com/subaru/misc/vacuum_highlight.jpg

 

I tend to think it's not the vacuum lines into the controls because it changes when accelerating and decelerating... the vacuum to the controls should be constant, so if they were the problem it would happen randomly... *shrug*

 

right now I just want to know if things are plugged in right... maybe somebody else in portland has an ea82t I can compare with and we can both stand there and stare at the hoses until something pops out at us... (:

 

on a side note, the 4wd works, but the cruise doesn't... not sure if the cruise problem is also vacuum related or not... but at least the 4wd is getting its vacuum...

 

 

Just a thought... I dont know if its the answer, but its an idea.

 

If any valving is missing (say if you replaced the vac lines and one maybe had a 1 way valve inside) when you accelerate you build boost... your HVAC works off vacuum, which boost is not...

 

Just an idea.

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yeah, you can see the white canister above the strut tower in the pic and the vacuum pump is where the hose ends below the strut tower...

 

I suppose I should buy a little vacuum gauge and see if it's putting out enough vacuum... I just wanted to know if my lines looked like they were all running to the right places, and that there was no one-way cehck valves missing or anything... (:

 

 

 

 

there is also a vacum pump on the same fender as the white canister..

at least on my 87 ea82t there is...

just a thought

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Well I just went through a whole bunch of vacuum mess up's after my new motor swap in, from not paying attention. Looking at your picture, yea it doesn't look quite right, but hard to say with out standing there. But looks like your check valve is in the wrong spot (it's after that big round plastic tee atm, thus not holding vacuum??). Not sure about a few other things also. Will refer you to the following diagram which may or may not help you out (also should be under your hood)

 

vacuum.jpg

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  • 3 months later...

ok, so I've narrowed it down to the single vacuum line that runs down the left from the vent controls, hangs a right behind the stereo towards the glove box, and then goes down behind the stash/ash tray area...

 

it's not holding air like the other 2 lines that come from the vent control... so the vacuum is leaking from there and causing the defrost to slip back to default front vent...

 

so... what am I getting into in order to replace that? is it something that can be repaired? will I have to take much apart? anybody have pictures?

 

just trying to get an idea as I'm about to eat some food and the start tearing the console apart...

 

thanks! biggrin.gif

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wow, surprising that nobody has replaced that unit before...

 

I'll be at a junkyard this evening to grab a master power window switch so I'll tear a car apart and check out that unit... it's possible that the leak is in the line that runs down to the unit and not in the unit itself...

 

if it's easy enough I'll just grab that part at the yard just in case...

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ha ha! very funny... the defrost control isn't behind the stash/radio area... it's behind the glove box... but at least now my center console is pretty clean...

 

I've found the source of the defrost problem... it's the vacuum unit (03H25) that pulls the lever for the defrost box... there's a leak in there and it's not holding the lever open and the spring is pulling it closed...

 

it's a *************** to get out... there's a screw on the back of it for some reason... seems like the 2 screws on the front would be enough... I don't think I'll be putting that rear screw back in...

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