Rusty (by the way, they still make gun oil),

I suppose the def vents can be mechanically blocked. Remove the radio and look into the opening to the left. There you will find the short/long throw pod. You could fashion some kind of mechanism to lock the vents closed by manipulating the linkage there. You will need to mechanically open the dash vents as well, if not already open.

All this provided you have the Climate Control system ACIII (or whatever its called, 1986-89 560SL). I suspect similar for earleir vacuum controlled systems, but I am not familiar with them...

Review the diagram on my page and pay close attention to the default or relaxed position of each pod (Spring actuated). That spring in each pod is kinda stiff, I'll tell you! It takes a good bit of force to compress it (and I'm amazed the vacuum generated in our systems is sufficient).

__________________
RM Smith
1988 560SL

"Where is it again that we are going, and why are we in this handbasket"?