Hey,

In my 86 320 SDL my defroster works ok when the windsheild gets foggy, but my heat wont work at all. What is the problem. Isnt this common among mercedes?

 

Yes!

It is very typical for MB climate control systems to fail. Sounds like vac pods are shot! The trouble is, that in most cases, you must remove the whole dashboard to gain access to replace vac pods! There may be other reasons too such as a vacuum hose leaking somewhere and that is a good place to start. If you have a Mity-Vac, you can test all you vacuum hoses not only for the climate control, but engine too.

Helps if you have a manual handy so here is a free site you can tap. I think it's only good for the 300D, but the 87 300D has the same engine as your 86 300SDL, so the info is the same for the engine, not sure about the climate system though, but I wouldn't think they could be all that different! http://skinnerbox.steaky.org/Service/Library.html

Cheers............BB