[pepito]

I just bought an '85 300D last week. It's my first Merc, and I'm having trouble figuring out the HVAC controls as I don't have an owner's manual.
Besides that, I'm pretty sure the HVAC controls aren't working properly anyway. Basically, when I start out in the morning I can't get any heat/fan until I drive about 20 miles.
Can anyone explain to me how the HVAC controls are supposed to work, generally?
Any ideas what my be causing my specific problem?

 

[jdc1244]

Only to say...

….mine does the same thing, almost. Perhaps after two or three miles or five minutes in stop and go traffic will the fan start and everything works correctly. The defrost works right away (first button on the left); I use it to “jump start� the system – that only works one out of ten times. Mostly I just wait for it to come on when it feels like coming on. I’m thinking the hose or tube that samples cabin air for the ACC is clogged or leaking or both. That may cause the sensor to not work.

 

[wdba123190]

Your system is actually supposed to do that. Mine does it as well. The fan will not sta...

Your system is actually supposed to do that. Mine does it as well. The fan will not start blowing until the engine is sufficiently warmed up to blow warm air out the vents. Personally I love it because I can start driving and set the heat where I want it and it will turn on when it's ready to blow warm air and I don't have to keep checking to see how warm it is and get blasts of cold air. The defrost works all the time as a safty feature. In fact the defrost is on a seperate, more reliable system (no bells and whistles) so even if the rest of the heating system blows up for one of many reasons (electrical, vacume, etc) the defrost will still work and keep you from going off a cliff.
-M-