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Vacuum tanks

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I tried this in the build forum but buried it under other pictures.


The PO of this MJ hooked up these two Vacuum tanks and the laid them on the electrical relays under the hood. Now, He led me to believe that the jeep did not have them origionally, and he needed to install them to make the HVAC work properly. He said they were to be installed under the front bumper (but as you can see, he replaced the front clip!).


Question is, they don't seem to connect with any of the HVAC equipment...they actually connect in one spot on the manifold, as marked with the green circle.


Can anyone advise on thier purpose? The A/C does not work right now (PO used hose clamps on the compressor line :nuts: so it has leaked down). and...does anyone have a vacuum drawing for the Renix 89 4.0?



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Those are vacuum reservoir tanks. The ones in your picture are the type with two chambers, typically for vehicles with cruise control. That type we sometimes refer to as the "blimp." The ones for XJs and MJs without cruise are round, about the size of a softball, and have only one chamber.


The purpose is to maintain vacuum for the HVAC control flappers when engine vacuum drops -- like when going up long upgrades and/or pulling a heavy load. They are normally mounted behind the front bumper on the right-hand side.

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