SL500 air vent problem

You may have seperate blower motors for different vents. You could also check your fuses to see if one has blown.

Yeah, checked all the fuses, the Climate control unit responds well including diagnostics, it even registers the vents opening and closing when I do it manually with a screwdriver. I'm inclined to think it may be the Vacuum Valve actuator. which is what I am afraid of.

This turned out to be a disconnected Vacuum hose behind the firewall. Once I located the loose connection (small thin white tube) and connected back to the engine hose. Vents began to work after I started the engine and ran for few minutes.

Scottc, I have the identical problem with my 99. Could you be a bit more specific as to the location of the thin white tube? Thanks

Thanks Scottc. Found it and fixed it!!!!!

Glad you found it, probably saved yourself $200....I'm re-doing my convertible top in the next couple of weeks (getting all the parts and tools together), can't see paying someone $2k to do a lousy job (got the top on Ebay, and an installation video) looks easy but tedious, lets see how it goes...

Knowing my local M-B shop, I think it saved me a lot more than $200. Let us know how the top installation goes. Have a great summer, thanks again.

I have the same problem, connected white hose, ran a few minutes then stopped, any ideas?

I also have 99 sl500, can you please let me know where the white tube is?

Where was the hosecond located? Do I need to remove console? Other feeds said sensor or control module. Fuse box under hood is fine but I also,read there are 3 boxes where are they?

This issue is normally due to a vacuum leak, like a loose vacuum line, but the most common leak is a split on the underside of the Vacuum Distribution Block. It is located near the firewall.. you'll need to remove the large flat cover to get to it. On the underside of the block, there is a ball bearing that works as a seal, check for a split/crack here. Reseal with epoxy or similar. Or just buy a new block: https://www.pelicanparts.com/More_Info/129800 1478.htm?pn=129-800-14-78-M22

Thanks, fixed it in 1 minute. In case anyone is trying to locate it: the small white hose is the diameter of a swizzle stick located almost in the center coming out of firewall accessible from drivers side; connects to black hose.

Thank you all. Will try finding it tomorrow. Leo