I just went to a computer surplus place and bought three 12V muffin fans (DC of course) and screwed them into the front of the evaporator inlet behind the passenger floor board. My car didn't have A/C from the factory, so my ventilation system is very different. The A/C was an aftermarket add on, which I converted to R-134a. BTW the fans cost about $2 each. Here's a pic. Also, I don't have the bowtie thingie and the only intake to the evaporator box is the one you see. I think other 911s with factory air have another intake for the A/C. BTW. I get A/C air from my top, center and underdash vents, I think most of our vintage 911s get it from the center vents only. I also don't get squat for air velocity from the vents.
