At the moment it's running at a single high speed and is quite noisy.
How do they work? I note that there are three leads coming from the fan
motor, two of which are connected i.e red & blue. The third is white and
isn't connected to anything, I assume it's a tapping on to the field coils
to reduce the magnetic field, and cause slippage to slow it down. would this
cause the motor to run at a higher temperature? or am I barking up the wrong
tree here. I'm loathe to try connecting the white lead without some
guidance.

Don