87 SDL

I've only got defroster no matter what setting I have the fan on.

I'm assuming I've got a vacuum leak somewhere but can't find it. Is it in the dash? If so what's the best way to get to it? Windows, door locks, all work fine.

I see a pink vacuum boost/reducer/transducer/thingamabob when I pull the controls out of the dash does this have anything to do with it?

Thanks,
Bill

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'87 300SDL, intensely modified Greasecar setup, with nickle plated heat exchanger, 3 valve setup, 312,000 miles
'95 Suburban diesel, Greasecar basics, 16 plate heat exchanger, mercedes fuel lines, Racor filter
'85 Renault Alliance converted full electric vehicle