I've made some picture and hope they will be a help to wire your fresh air blower. The wiring from my '68 912 has never been touched and the blower functions as it should.
The blower can operate at two different speeds. The switch in the dash therefore has three positions:
Pushed to the dash - OFF
Pulled to first "click" - LOW SPEED
Fully pulled - HIGH SPEED
The wiring of the back of the switch is shown below. Looking at the switch, a control light could be installed, but the wiring and fitting are not supplied. Perhaps someone (John?) could confirm the absence of the light and wiring:
Relay terminals:
85 and 86 - coil terminals
30 - mother contact
87a - connected to 30 when not activated
87 - connected to 30 when activated
The wiring of the relay:
Below the fresh air blower in the smugglers box and as a detail pic its terminal block:
The following is the most important info, I guess. I found the following wiring diagram for the blower in the 911 factory manual. So basically copyright protected.
And as a last picture my cocoa sunroof 912 from where the pics are taken.
I hope this helps wiring your fresh air blower.
Otto