The default function with a total loss of vacuum is defrost so based on your symptoms it may just be that a vacuum line got knocked off while you were working on it.

On the SDs you can access all the vacuum pod control valves by pulling the carpet on the passenger side kick panel. They are in a nice vertical row there and you can test each pod from that point wihtout having to take out the console like you do on the 123.

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique