Thank you! I had gone over this sheet and ordered a 3 way to plug in the grey line aswell (water heater) sounds like I need that vacuum to allow cold air in, thing is it sounds like I shouldn’t need that to have vacuum in order to get air out of the vents. I’ll re check lines tonight and hopefully I receive the air splitter. Thanks againHere are the pertinent pages from the 88 shop manual, which is pretty much the same system as all G bodies OTHER THAN the automatic A/C system found in higher option carlines (I think Buick and Olds...never seen one in real life)
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