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

bump tht...

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Think Alternative Energy!
300CD '80 (now gone but not forgotten...)

I've taken my 80TD's apart three times, with one replacement from the yards. WD-40 is a bad idea as it causes rubber to swell. WD-40 is a bad idea on all rubber and plastic. Use sythentic (ie...silicone) grease or lithium grease and may get better- mine did. Be sure to check that the lower plunger actually opens and closes. Be sure to check you have vaccumm to all the lines which enter the servo. It's really not complex inside- just delicate. Like a big very simple clock.

I believe Performance Products is selling a kit of modern components that replicates and replaces the servos. It's reliable and should never require periodic replacement such as the first-generation ACC servos do. The traditional servos can both seize internally OR crack on the outside. The "rebuilt" units with aluminum bodies aren't worth the money unless the internal mechanisms are new.

My suggestion and advice would be to investigate/purchase the Performance products solution. I remember it to be around $500-600 -- this is roughly half the cost of a new servo from MB.... and other than the aluminum-bodied "rebuilds" I believe that MB is the only company selling new units. And they've been playing around with the prices on them in recent years.

Cheers,
Gerry