Radiator Fan Switch

prelude_h22 · Post by **prelude_h22** » Mon Aug 20, 2018 7:46 pm

Hi Guys,

Just wondering if anyone has any experience in rad fan switches.

I think mine is knackered on the s2000 and the fans are constantly on, even when the engine is cold and on pre-ignition.

Was going to order a genuine Honda one but they are like £65 ish.
Aftermarket is around £15
https://www.ebay.co.uk/itm/Radiator-Fan ... 1438.l2649

Has anyone tried a Mismimoto fan switch?
Whats the benefit of the switch kicking in the fan 15 deg lower than stock?
https://h-tune.co.uk/mishimoto-fan-temp ... -80-honda/

Thanks guys

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Tue Aug 21, 2018 12:09 pm

prelude_h22 wrote:Hi Guys,
Has anyone tried a Mismimoto fan switch?
Whats the benefit of the switch kicking in the fan 15 deg lower than stock?
https://h-tune.co.uk/mishimoto-fan-temp ... -80-honda/

For a road car - absolutely none.
You could even end up fighting the thermostat with that much of a rad fan temp drop.

prelude_h22 · Post by **prelude_h22** » Tue Aug 21, 2018 2:28 pm

Thanks Wurly,

Didnt think it would have much benefit - suppose if your on track it may help.

Will probably go genuine OEM for peace of mind.

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Tue Aug 21, 2018 5:20 pm

Just looked at the ebay item you linked.
Cambiare stuff is fine - it's European, not Chinese cheap copy stuff. I'd go for that if I were you.

prelude_h22 · Post by **prelude_h22** » Tue Aug 21, 2018 8:27 pm

Thanks Wurly, I think your right.
The cambiare one seems like the one to go for, at that price I can get a spare. lol.

Post by **NafemanNathan** » Tue Aug 21, 2018 8:35 pm

If the signal wire has somehow managed to earth itself this would also explain the symptoms you're experiencing.

prelude_h22 · Post by **prelude_h22** » Tue Aug 21, 2018 8:37 pm

If the signal wire has somehow managed to earth itself this would also explain the symptoms you're experiencing.

The switch is a two wire type, would one be a signal?
Or would this be for three wire switch type?

If it were signal issue should I get a MIL light?

Post by **NafemanNathan** » Tue Aug 21, 2018 8:51 pm

A lude has a two wire type. Green and black. Green is the signal wire. The way you install a manual fan switch is to splice into the green signal wire, run it to a new switch and connect the other pole to an earth.

So basically earthing the signal wire turns the fans on.

prelude_h22 · Post by **prelude_h22** » Tue Aug 21, 2018 9:03 pm

Ahh that is interesting.
The s2k is also a green and black two wire type.

So running it to another switch the way you describe I assume would be the fan relay?
So could be a bad relay?

Post by **NafemanNathan** » Wed Aug 22, 2018 6:59 pm

I haven't delved too far down the line, but it wouldn't be a relay causing it I'd have thought. It'll either be the switch causing it to earth (as it should) or the signal wire earthing. A relay if there is one couldn't really cause it to earth the signal wire.