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bad cross brace vacuum valve

Posted: Mon May 17, 2021 10:07 pm
by captainOCD
Not sure what the correct terminology is for this guy, but mine seems to be bad. I think it's referred to as "AC Kickdown' on my vacuum diagram from Roger, looks like it's tied into the evap system though maybe. Either way it doesn't hold vacuum, so for the time being I routed the line and capped it off.


On it is part number 928.110.429.07. I can't really find mention of it anywhere. What is this thing, and are there going to be any negative consequences of running the car without it functioning? I'm still waiting for some other parts to come in this week before putting the rest of the car back together.


It normally mounts to the cross brace over the intake.
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One line from it runs back to another valve near the coolant bottle. The other to the plastic T that goes off to the filler neck, then to the throttle body.
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Part number on it.
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Re: bad cross brace vacuum valve

Posted: Tue May 18, 2021 8:49 am
by SeanR
It's not the valve for the A/C idle, it's a valve for the fuel tank emissions system. Last I heard it was not available so you'd have to find it used. The A/C idle is controlled by the LH/EZF on the US 85+ cars.

Re: bad cross brace vacuum valve

Posted: Tue May 18, 2021 10:18 am
by captainOCD
So right after I posted that last night I realized if it's not working I've been running without it functioning for 3 years now. I've just capped off the vacuum line to the diaphragm now so I don't have that vacuum leak.

Do you know if the vacuum applied to the diaphragm opens or closes the valve? Maybe something else can be sourced to replace it with.

Re: bad cross brace vacuum valve

Posted: Tue May 18, 2021 12:30 pm
by captainOCD
I went and took a look at my 84 parts car at lunch time. Looks like it has a valve that looks the same mounted to the fender, and it holds vacuum. It's got a 944 part number (94411042900) on it though, so not positive if it's the same in operation (as far as vacuum on vs off goes).
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Re: bad cross brace vacuum valve

Posted: Tue May 18, 2021 9:11 pm
by captainOCD
After further inspection, while the diaphragm on the one from the 84 holds vacuum, the diaphragm doesn't seem to do anything to shut off flow between the two sides of the valve. It flows between the two no matter the state of vacuum.