S4 / Sprint Electric Cooling fan wiring

[pharriso]

If you look through the various S4 & Sprint wiring diagrams you will see that Lotus omitted the Radiator cooling fan wiring.

I looked through wiring diagrams of other Lotus models of the period & they are similar to how the S4 & Sprints are actually wired from the factory.

Federal Elan Sprint Engine Cooling Fan Wiring_V2.pdf

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Notice in all cases the Thermal "Otter" switch is taking full motor current, thus shortening it's life.

I've come up with the attached wiring that adds a relay & optional manual switches & indicator light:

RadiatorCoolingFan_Wiring_V1.00.pdf

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Power for the radiator fan is taken from the large headlight feed wire at the headlight relay. I've bolted my relay to the side of the radiator on the blanking panel.

[gjz30075]

Thanks Phil! Yet another addendum to add to the book