Testing the cooling fans

chrisw2811 · Post by **chrisw2811** » Tue Aug 29, 2006 11:03

Does anybody have a quick test for the cooling fans? The missus left the Excel ticking over on the drive (i.e. for me to put in the garage) but omitted my trick of leaving the heater full on with the windows open (engine overheating paranoia). When I got in the temperature gauge indicated v high 90s but no sound/sign of fan operation. I got it in the garage quick with the the heater full on and have since checked fuses - ok. I presume the otter switch should have turned the fans on, so would like to check what does and doesn't work. My thoughts were to check if the fans can operate and then work from that. The fans spin freely by hand. Should I short the otter contacts? Was there a link to a wiring diagram to enable one fan to operate continuously or to by-pass the otter switch for operation? Thanks, Chris

GavinTaylor · Post by **GavinTaylor** » Tue Aug 29, 2006 13:03

Yes, if the gauge is reasonably accurate, I'd expect the fans should have come on, too.
Yep, to test the fans, just connect the otter switch contacts. If the fans now run, then the otter switch is a suspect.

Gavin

amarshall · Post by **amarshall** » Tue Aug 29, 2006 16:33

Don't forget to check the fan fuses (one each) and fan relay (if fitted) if the otter-switch bypass doesn't turn them on.

amarshall · Post by **amarshall** » Tue Aug 29, 2006 17:33

Fuses & relay layouts should be in both the parts manual and your owner's manual.

chrisw2811 · Post by **chrisw2811** » Sat Sep 23, 2006 22:15

Fans work fine when I short the otter switch connections so it looks like a duff otter switch. Also, the otter switch is cable-tied into its body as the clips look suspect, suggesting it has been apart before (probably several times). Options - new otter switch or look at modern alternatives such as Angus' upgrade?

Skeggy · Post by **Skeggy** » Sun Sep 24, 2006 17:40

Just in case you don't know....apparently the otter switch is the same as used on Scimitars.
Scimitar suppliers sell them a lot cheaper than Lotus suppliers so I've heard/read.

Pete Boole · Post by **Pete Boole** » Sun Sep 24, 2006 22:58

Hi Chris

I'd go for the modern alternative: You can then choose the temp at which the fans come on. You could even control each fan separately if you wanted to.

Pete

chrisw2811 · Post by **chrisw2811** » Mon Sep 25, 2006 20:27

The wiring diagram shows both fans switched via a single relay triggered via the otter switch. Would individual control require a second relay (and fuse)? A by-pass switch parallel to the otter switch is the cheapest option.....

Pete Boole · Post by **Pete Boole** » Tue Sep 26, 2006 08:32

Hi Chris

Yes, controlling the fans individually would require two relays (or three if you wired the fans in series for slow speed operation and parallel for high speed operation at different engine temperatures!).

Pete

chrisw2811 · Post by **chrisw2811** » Tue Sep 26, 2006 21:43

I'm waiting to hear if Mike has any cheap otter switches at Lotusbits

before reaching a decision.....

Tango190 · Post by **Tango190** » Mon Jul 16, 2007 12:33

Guys,

Bringing back to life this thread as I can't see the point in starting a new one for the same issue.

Except ...

My car is a very early Eclat Excel (Regd - 83) and only has a single fan unit.

Can I still do the test by bridging the otter switch out to see if the fan comes on.

I've only just got the car back again after a period of use by a friend and he has stated the fan doesn't seem to come on.

Hence I'd like to test it and haven't got a manual with wiring diagram yet.

Regards

Bob (aka Bob Blewitt from the old forum)

16VJay · Post by **16VJay** » Mon Jul 16, 2007 15:53

Hi Bob,

Yes, shorting the Otter switch wires should fire up the fan on your car. Irrespective of the car, the Otter switches all work the same way and shorting them out should start the fan(s) if all is well.

Cheers,

Jeremy.

Tango190 · Post by **Tango190** » Mon Jul 16, 2007 17:28

Thanks for that Jeremy,

What makes me a bit suspicious is my mate changed the otter switch for a "green" one from Paul Mattys.

Could be a dodgy otter or my dodgy mate

I'll give it a shot.

Thanks

Bob

lambert.john · Post by **lambert.john** » Tue Aug 14, 2007 15:30

I have a problem with the cooling fans failing to turn off. My mechanic has pinpointed the otter switch as the likely culprit. Can someone kindly tell me whereabouts under the bonnet this component is located , please? And who/where is the best source for a replacement?

John Lambert

Steve C · Post by **Steve C** » Tue Aug 14, 2007 16:11

It's located in an alloy pipe set into the top radiator hose. It is meant to be a press fit but is normally held in with wire.

You can check if by measuring the voltage across the two pins... if it's zero, it's switched on whether it should be or not!

I don't know of any sources except Lotus dealers ... it has a unique fitting compared to most cars which use a threaded connector.

The Lotus Grand Tourers

Testing the cooling fans

Testing the cooling fans

Early car - single fan - fan testing