captainOCD

Found out a couple weeks ago that all 5 of my vacuum solenoids were leaking when energized. Since hvac vacuum solenoids aren't available new anymore and used ones are $50 each and with an unknown lifespan left I decided to look around for something else that would work.

Stumbled across this mercedes vacuum solenoid block that looked promising so figured I'd give it a shot.



Found a wiring diagram from a video testing one of these. They're solenoids so they work just fine with a common ground and switched power to the pin for each solenoid like the 928 uses.




Used mercedes parts on ebay frequently come with the electrical connector, but since I didn't want to mess with another used part I didn't get a connector (maybe that's able to be obtained separately?). So for now I used bullet style connectors onto the pins of the mercedes valve and adapted to the spade terminals that the factory solenoids use. Just left the caps on the two unused ports.






It tucks in there nicely for the most part. I still need to make a bracket or something so the other side can srew in too, but for now it's not flopping around or anything. All the actuators work as expected now and I could visually tell that my recirc flap switches fully to recirc now whereas before it didn't have strong enough vacuum to completely move.

Needs some polishing, but I think this has promise to be a good substitute for the NLA original solenoids.

Zirconocene

That's rad, great find. I can't quite tell from your pictures, but is the connector on the Mercedes part different than the standard 14 pin connector that you can see in other parts of the 928? I mean, apart from the pin count. Not that you should do it this way, but if you chopped down the 14 pin connector to 8 pins, do things fit, from a width perspective?

I believe that it's part of the same connector family, so it should be available, similar to this: https://928srus.com/products/911-612...8b9d88dc&_ss=r

Cheers

captainOCD

I think the pins may be the same size, but the spacing of the rows appears to be much closer together.


This one on ebay shows the back of the connector:




https://www.ebay.com/itm/18395935600...Bk9SR6CvkoacZA

Kiln_Red

Awesome. I've got my HVAC opened up on my '84 while I try to refurbish it, so this is timely.

Zirconocene

I dug around and found this, but maybe it's not quite right for this part: https://www.pelicanparts.com/More_In...ader=Y&SVSVSI=

ETA: For those interested, the OEM for these kinds of housings is/was Kostal, and the part in question is their 9628 part number. I looked around on their site but didn't see anything from them. The current MB parts look like they have a Bosch symbol printed on them, so maybe that's where the modern source is.

Cheers

captainOCD

Yeah pin spacing looks too far apart between the two rows