hooziewhatsit,

Are you testing w/o the blades? If so the PWM might not lower the RPM due to not having a load/drag on the motor. It could simply be that the internal magnets can run the motor at the full speed with lots of PWM (lower % on time) with no fan dragging it down.

Another test I can think of is to just add a resistor inline to lower the voltage. It'd be interesting what it's output is at 6 Volts.

But then I run into the problem of how to get 6 volts. I thought I'd easily find a 12V to 6V 'box' for use on pre-50's cars with a mixed power system. However I can't seem to find such an animal...

too bad the batteryies don't have a 6V tap on them.

Ben