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Ha! I'm redoing mine for the second time... discovered I had a bad vacuum valve in the HVAC controls after getting it all back together. Since it was out again I decided to redo all the gaskets properly, including pulling and "restapling" the one on the defrost door. I hope to reinstall it tonight barring further issues.Rebuilt my HVAC box with a new heater core, new seals and cleaned/lubed all the moving components. Then after lots of cussing and about 3hrs, finally got it back in the truck. That is not a fun job
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Is the defrost door supposed to have gasket all the way around like that? I only replaced the 2 little strips at the end where the staples were. I pray I don't have to do this again for a very long time. If I do, I will redo the entire system lolHa! I'm redoing mine for the second time... discovered I had a bad vacuum valve in the HVAC controls after getting it all back together. Since it was out again I decided to redo all the gaskets properly, including pulling and "restapling" the one on the defrost door. I hope to reinstall it tonight barring further issues.You must be registered for see images attachYou must be registered for see images attachYou must be registered for see images attach
Not entirely sure TBH. The old one was crumbling goo and appeared to have torn at the ends. As I tested the HVAC controls I noticed there was a gap between the door and case when fully closed. I assume you'd not want blowby if the door is meant to seal. I chose to gasket on attempt two rather than have to do an attempt three lol. Plus, the surface rust pattern indicated there was something there at one time.Is the defrost door supposed to have gasket all the way around like that? I only replaced the 2 little strips at the end where the staples were. I pray I don't have to do this again for a very long time. If I do, I will redo the entire system lol
Never in the unfortunate multitude of brake failures I've had on GM vehicles has that valve "shut off" anything. If it did you wouldn't get that spongy pedal and half of the master emptying itself. All it does is turn on the warning light.
If the system is that neglected it is possible that the assembly is plugged with rust. You can take the back end of the valve (the rear proportioning side) and see how cruddy it is in there. You could also loosen the line to the rear brakes and see if you get fluid out of the valve at that point.
In my case valve activated and brakes were firmSame here. If I had a nickel for every time I lost a rear brake line, the pedal squished to the floor and I lost all my brake fluid... I wouldn't be rich, but I'd have a big pile of nickels.
I have firm pedal as well.In my case valve activated and brakes were firm
Here is an explanation of how a combination valve should function.
How Do Combination Valves Work?
techtalk-mpbrakes-com.cdn.ampproject.org
Rebuilt my HVAC box with a new heater core, new seals and cleaned/lubed all the moving components. Then after lots of cussing and about 3hrs, finally got it back in the truck. That is not a fun job
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