I have a 1978 240D that has the manual a/c heat control with the a/c knob you can turn and push/pull (not the wheel). I pulled the dash and climate control box to replace the heater core, and while going through the vacuum controls for the fresh air and leg flaps, I found the vacuum switch on the back of the a/c control knob to be leaking. Part number on the switch is 123 800 00 73 and it looks similar to the vacuum switches for the door locks. Tried to order it from Mercedes but they said it's NLA.

I'm wondering if anyone knows of a way to disassemble this to repair it. I've been trying to separate the large washer piece on the front from the shaft with no luck (and I don't want to break it). I'm hoping if I can get the shaft out I can clean it up and replace the seals inside to fix it. Thanks!

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Update for those wondering or who run into this situation. I cut the washer piece off and pulled it apart. Unfortunately the seals inside weren't o-rings, they were a rubber seal formed to a specific shape so they weren't going to be easy to simply replace. They were old and brittle too, I went to pull one off and it just immediately split in half.

I decided just to bypass this switch. It controls the leg vents, so hooking the leg vent vacuum pod directly to the a/c vacuum controller means the leg vents just automatically shut when turning on the a/c instead of having manual control by pushing in/pulling out the knob. Seems like a good solution to me because I never use A/C directed at the feet anyways.

You might try searching ebay.de with the part number, I've managed to find and buy quite a few N.O.S. parts that way .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better