Seems like it is usually one of those under hood rubber connectors, or the check valve going to the interior. The interior stuff can all be diagnosed from the passenger footwell IIRC. You need one of those mityvac hand pumps ideally to test each branch.
On Feb 17, 2018 9:20 PM, "Rick Knoble via Mercedes" <mercedes@okiebenz.com> wrote: >Any suggestions on how to go about >diagnosing the cause? Nope. Rick _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com