The factory included these reservoirs so vacuum actuated accessories wouldn't stop working on a long climb in a nutless car that was basically WOT to lug its own weight up said hill. Without your HVAC would default to whatever spring loaded position it was set up for.
Vacuum Sphere of Mystery?
- Thread starter DWCaprice2017
- Start date
Depends on the model and options. I know 84-87 VIN 9 cars have a large single port ball for HVAC and cruise.
Hi!
Thank you for the diagram!
I believe that’s the XJU version that I have as the sticker near the fan shroud. The problem is that the diagram doesn’t show the hoses that goes to the sphere vacuum reservoir above the canister nor the hoses that goes to the cruise control unit.
Thank you for your response!
“Vacuum actuated accessory”, like the cruise control, I’m guessing.
Thank you for the info!
I’ve been looking for a non-emission hose routing diagram in the Chevy Shop Manual cd I have, guess I need to look harder! I wonder if the cruise control unit is bad, would that affect the engine performance (cause a rough low idle)?
Thank you for your response!
I’m embarrassed to admit this, I’ve been looking at the responses to my sphere question in random order—the hazard of using a cellphone to view these—I saw yours last. Had I seen it earlier, I wouldn’t have asked my later questions on this thread!
Typically, the cruise servo will not leak if it goes bad as the solenoid vacuum valve fails closed and the vent valve fails open when the unit isn't operating. Although you can't rule that out if you know the unit is fubar or the valve leaks or is stuck. You can take the smaller hose off and plug it to test. The fat line just goes to the vent valve release above the brake pedal.
If you want to test your servo, you'll need to do some electrical tests on the vacuum/vent valve solenoids, etc.
Go here for a pdf of the K34 electronic cruise control troubleshooting manual:
If you want to test your servo, you'll need to do some electrical tests on the vacuum/vent valve solenoids, etc.
Go here for a pdf of the K34 electronic cruise control troubleshooting manual:
THANK YOU very much for the manual!Typically, the cruise servo will not leak if it goes bad as the solenoid vacuum valve fails closed and the vent valve fails open when the unit isn't operating. Although you can't rule that out if you know the unit is fubar or the valve leaks or is stuck. You can take the smaller hose off and plug it to test. The fat line just goes to the vent valve release above the brake pedal.
If you want to test your servo, you'll need to do some electrical tests on the vacuum/vent valve solenoids, etc.
Go here for a pdf of the K34 electronic cruise control troubleshooting manual:
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