1992 300D with 232,000 miles. Lately there've been instances of the center vent not opening. But thus far it eventually works. Today, for example, I couldn't get it to open on a 20 minute drive. But I turned on the car five hours later and the center vent popped open.

So I figure that vacuum actuator is on its last legs. With it opened, is there some easy way I can force it to stay open all the time? I'm as much into the compulsive need to make everything in my car work as the next guy....but there's not a chance I'm ripping apart the dash (in my case, PAYING someone to do it) just to have a working center vent.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 157k miles
06 E320 CDI "Rutherford", Black on Tan, 175k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 144k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 70k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

IIRC the center vent actuator is inside the airbox so I think the answer is no.

Sixto
87 300D

Seems like a dumb design....they had to know it would eventually go bad....how hard is it manually to open and close a vent?

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 157k miles
06 E320 CDI "Rutherford", Black on Tan, 175k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 144k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 70k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

When I got my '87 wagon there was a piece of wood wedged inside the vent to force it always open. Not elegant but...

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punkinfair

Not necessarily the actuator, not too long ago someone on here maybe Jeremy posted about the vacuum control manifold that uses an electrical signal to open a vacuum valve to allow vacuum to what ever pod is needed.The one on my wagon is intermittent to the center vent usually will eventually come on,however hitting a hard bump in the road will just about always make it come on,so i suspect the failure of a solder joint or circuit trace not the vacuum pod.The writeup that was done is excellent wuth good pictures ect,hope you can find it with the search! Don

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Red Green "This is only temporary,Unless it works!"

97 E300D 157000 miles
87 300TD ?141k? miles

Here ya go -

PeachPartsWiki: Climate Control Vacuum Valve Repair

PeachPartsWiki: Manually Controlling Center and Footwell Vents

Sixto
87 300D