On the 1985 300D the a/c works great (actually as well as one that has been converted to 134a can work). My problem comes up when I want to turn the a/c off and just have the vent blowing. I mash the button next to the off button and the fan blows fine for a couple/few minutes and then I hear a relay click and the fan shuts down. I can run the a/c again (middle button) and go back to vent and it does it again. It does not seem to matter what temp setting the wheel is on. Where do I need to look for resolving this?

Another question - I just replaced the outside air/recir air damper vacuum actuator and when I went to purchase it (purchased local) the MB system said "not applicable" to my car (I supplied the VIN #). In addition, when the MB sales person called MB they tried to talk him into supplying a different one. The part that was in the car was 123-800-12-75 which is what I finally ended up with. Why would they do something like this?

thanks

It could be that the pushbutton unit is having a problem. I have resoldered a million of them.

On the part#, it could have been updated or something. Also, the new parts sytem is not 100% accurate.

pushbutton unit is brand new
 

thanks Donnie
I was wondering about the cc boxes located underneath the dash board above the glove box.