I am still trying to figure out all the nuances of my recently purchased 1983 300D. I bought a manual to help me figure out the heating a ventilation controls and a Haynes manual for the mechanical bits. Half the time everything work likes it suppose to. At the moment it is not. For some reason the fan does not come on at any speed. I can hear the dampers move when working the buttons and I have installed a couple of bypass swithesto make the fan run and with this I can tell the thermostat is working properly. What I can't figure out is why the fan works some days and not others.</P>


In chasing down all the wires I found what appears to be a control logic box located under the dash just left of the glove compartment. When I asked the dealer for the cost of a replacement unit he couldn't even find it in his shop manual. The box didn't show up in the wireing diagram either. He said if I gave him a part number he could probably get the part.</P>


Has anyone else had a similiar problem? If so, how did you fix it?</P>


TimK</P>