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Radiator Fans not coming on :-(

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I've got an 1989 Esprit NA HC (carbs) and basically the car overheated in traffic and boiled and pissed its coolant all over the floor. A bit of investigation and I realised the radiator fans hadn't kicked in when the coolant reached its max temperature.

I've taken the fan relay out and hot wired the inputs to check the fans work. They do, all three.

I've taken the wires out of the top thermo switch and wired them together and nothing... no fans... So have I done my checks right? Does this mean that my fan relay just needs replacing? If I do this and it still doesn't work, is it then down to the wiring from the thermo-switch (in the back) to the relay (in the front)? or is there more to this? How do I test to see which part of the car is not letting the car switch on its rad fans when the coolant reaches temperature?

Thanks, Gary





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Not knowing the layout of the Stevens loom I could not tell for definite. 

But I would presume that if the relay was not working then it still would not work even if you bypassed the thermal switch.

The thermal switch is just that, just basically like an on/off switch so when you bypassed this the fans should of come on if this was the problem.

Which would tell me your relay is the problem or as you say a possible damaged wire from the bay to relay.

I would normally test the relay, if this turned out to be ok, then I would run a continunty test on the wires to check for a break/ poor repair will electrical connectors etc.


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It's worth stating that the fan circuits draw relatively high amperage. If the relay socket connectors get 'warm' as a result, they might have loosened, backed-up into the plastic, and are no longer making contact.


So, remove the relay(s), have a look at the wires too (a gentle tug should not free the wires). Use an awl to tighten the 'mustaches'. When replacing the relays (ANY Lotus relays), support the wires underneath to prevent them from backing out.

Atwell Haines

'88 Esprit

Succasunna, NJ USA

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