Originally Posted by Rog
Originally Posted by Mark+4
I have an idea to replace the 2 speed switch with a 3, but I'd like to keep the original Knob on the new switch so want to take it off to measure up before buying a new one.

I have this little sketch left over from when I was butchering my dash. The switch shaft diameter is 6.3mm

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This switch might work?

Worth mentioning that these wafer switches only have a switch rating of around 1A and on the Duratec (don’t know about the GDI) it’s switching the negative side of the relay coil.
This was demonstrated to me by the mechanic at Borghi's after I had burnt out the circuit board and was part of the incentive to change my dash. When the fan is running at high speed and you turn the engine off you see the various dash warning lights fade slowly because the spinning fan motor becomes a generator and feeds power back into the system.

It almost makes one wonder if the heater fan system goes back to when cars had a positive earth system thinking

Part of Borghi's dash fix was to reverse the wiring to the fan to the more conventional system so that power goes to the fan from the switch/relay rather than the fan constantly having power and being earthed via the switch/relay. I don't know the technical details of how this was done.

Peter

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