A great little mod here by Anthony that uses one of the dial on off switches and the led on the heater control panel for what is normally for heated seats which many dont have.

In summer one of my two cooling fans died. While I waited for the new fan to arrive I decided to fit a fan override switch to give the one remaining fan a head start cooling me down in traffic.
 
I didn't like the idea of using the dash light switch by the left knee as I still use this for the dash lights. On a previous occasion I've had the centre console out and noticed all four rotary dials in the heater unit come with on / off switches built in. I thought I'd be clever and try use on of these for my fan override switch.

My idea was to simple use a variable resistor (potentiometer/pot) to attenuate the power getting to the dash lights. I started by removing the on/off switch by the left knee and measuring the current draw of the lights. It was 1.1A, so I made the assumption the resistance of all the dash lights 12.5 Ohm.