Peter,
That worked a treat. Three closed tight and one (driver side cabin) opened fully. Thanks for that. I'm assuming there's a flow of air generally when the fan is off which was concentrated by there just being one outlet open. It increases when the fan is operated and when the fan is off it's at it's least intensity. When the car isn't moving there's nothing from it at all so it must be drawing outside air past the element? (comments invited) Which I suppose it has to do.
Found another knob under there. Right of steering wheel and under dash beside the clock set button. A rotating black (like the old marshall amp dials) knob. Dash dimmer? I'll try it later.
Cheers.
