Intermittent Cooling Fans

Topics relating to the Lotus Exige S1 (series 1)
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JE5TER
Posts: 22
Joined: Mon Jan 29, 2007 10:06 pm

Hi Guys,

I noticed recently my S1 occasionally getting hotter than usual and realised that my cooling fans weren't on when the temp is above the point they usually kick in. Other times they are working just fine. I'm assuming a faulty temp sender but has anyone else had similar?

Thanks
JE5TER
C8LGY
Posts: 75
Joined: Thu Jun 13, 2019 10:27 pm

You should plug in an OBD reader and see what temperature the ECU is reading (brown sensor), and then compare it with the dash (blue sensor). It may be that one of the sensors isn’t reading properly - I had this with the stack sensor recently, which made it look like the fan wasn’t coming on, but it was just really the blue sensor over-reading.

If you haven't already, unplug the brown sensor cable and check the fan starts, to prove that side of it too.
JE5TER
Posts: 22
Joined: Mon Jan 29, 2007 10:06 pm

C8LGY wrote: Mon Jun 13, 2022 4:43 pm You should plug in an OBD reader and see what temperature the ECU is reading (brown sensor), and then compare it with the dash (blue sensor). It may be that one of the sensors isn’t reading properly - I had this with the stack sensor recently, which made it look like the fan wasn’t coming on, but it was just really the blue sensor over-reading.

If you haven't already, unplug the brown sensor cable and check the fan starts, to prove that side of it too.
Thanks C8LGY I'll take a look a look at that and check, but the fan definitely wasn't coming on, as I parked up and got out to listen... :D then the very next day it was working fine...

JE5TER
C8LGY
Posts: 75
Joined: Thu Jun 13, 2019 10:27 pm

Ah, intermittent problems are the worst to pinpoint! Next time you think that it doesn’t kick in, go straight to the brown sensor and unplug it. If it kicks in then you know it’s an instrumentation issue.

Do you know what temperature you expect the fans to kick in at too? It depends on what ECU you have (177/190/Emerald etc) too.
JE5TER
Posts: 22
Joined: Mon Jan 29, 2007 10:06 pm

C8LGY wrote: Tue Jun 14, 2022 10:30 am Ah, intermittent problems are the worst to pinpoint! Next time you think that it doesn’t kick in, go straight to the brown sensor and unplug it. If it kicks in then you know it’s an instrumentation issue.

Do you know what temperature you expect the fans to kick in at too? It depends on what ECU you have (177/190/Emerald etc) too.
I'm in Dubai so it gets pretty hot here... they usually kick in around 95... then of course I've the infamous bad earth issue as well, so the reading immediately jumps to 105, and cools down from there....
C8LGY
Posts: 75
Joined: Thu Jun 13, 2019 10:27 pm

Sounds similar to what I experienced; nothing wrong with the cooling system and instead just the blue sensor (Stack) reading rubbish. The dash actually has nothing to do with the cooling system, other than being a diverse source of instrumentation. The standard fan cut-in is 104C, or 92 C if the 190 ecu is fitted, but you have to read this input temperature through the OBD.

Since replacing my blue sensor and properly grounding the Stack at the rear, dash temperature is not only rock solid but 3C colder with no electrical load!
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