A few niggles... Fan switch and warning light

[majcd213]

Its nice to have the fan fail light... But I find that my nerves give out at a lower temperature than the otter switch comes on and I spend much time in jams worrying that the cooling system will fail... Or has already failed! I'd really like reassurance that the fan has actually come on, and a manual override switch for suspected otter switch failure. I think I can wire in both but has anyone done this? If so where have you mounted the switch and light?
Mike

[rbgosling]

Maybe a little camera in the engine bay, so you can confirm the fan is actually turning?

[Redlotus]

Its a while since i have this concern but I used to put on the AC as that puts the fans on if i recall correctly.

[POD2100]

I fitted a fan override switch a few years back for the Le Mans classic journey.

As the Fan relay is near the driver side fuse box I removed the cover from the relay drilled a hole in it and soldered a couple of fly leads direct to the coil side positive and the permanent feed (I think 30 & 86 best to check this first)
I then fitted a rocker switch under the dash near the bonnet release so if required I can just reach under and turn it on.
I didn't bother with a confirmation light as the Fan Fail light does seem to work and when the fans cut in the temperature drops very quickly.

I've never needed to use it but I have also replaced the otter switch (when it failed on) and housing with a generic replacement from Ebay.

[majcd213]

Thanks guys. I don't have a/c so sadly can't use that. Actually something that confirms the fan is turning would be safest because the fan fail light mainly seems to be a relay fail. I can envisage a non turning motor but functional relay so no light. However Im going to go with the switch in the foot well. Might try an under dash "panelette"... But I don't really like those as they look like an add-on.
Mike

[amarshall]

The fan fail really does detect a failed motor or wiring fault. It's all in the diodes. I speak from experience.

[majcd213]

Well it didn't detect mine! However, given the state if my previous wiring I'm not sure this will be down to the warning light alone.
Whilst we are on the subject of warning lights, I'd really like the low coolant sensor... Yes these two concerns are interconnected! Im thinking this wouldn't be too tricky to swap expn tanks and retrofit relevant gubbins??

[barker_001]

I carry (but have never needed) a short length of wire with two male spade connectors on it. If my otter switch fails I can unplug the leads from it, and plug the short cable onto the leads in its place, so the fans should run permanently. In traffic, I watch the temperature closely, and can normally hear the fan relay click into operation. The temperature then falls rapidly once the fans have started.

[richardw]

If the fan fails, an easy check is the fuse box. On my car, the fuse was OK but it wasn't making contact with the sprung holders under load. However the fan fail light did work.

Richard

[escape]

I've added a manual override for the cooling fan with a warning light in my Excel, just like I did in my Esprit. I often use it when in traffic, especially when I'm near my destination. I want to avoid parking the car with the temperature so high the fans are about to come on or have just come on. Flip the switch just a bit earlier and the fans get the chance to bring the temperature down by the time you arrive.

On both cars I've used the RHS switch and rewired this to the fan relay on the same pin as the Otter switch (BO wire). By adding a bridge to the lamp in the switch (WB wire) it indicates when the relay is engaged, so will come on if the Otter switch closes as well. You could wire the lamp directly to the fan motor for added reassurance, but the fanfail warning light will cover failure of the relay and fuse. If the ground wire of the fan motor gets disconnected, the warning light will not come on and the one in the switch will be on, regardless of how you wire it.
I did have to cut a small section of the switch cover, to be able to see the light clearly with the switch off.

Filip

[majcd213]

Hi Fillip, that sounds perfect... Although I think I will use a new switch. RHS= HRW? I was going to use one with the illuminated toggle to get over the visibility issue. Do you have a wiring diagram by any chance?
Cheers
Mike

[escape]

Yep, rear heated screen or heated rear window
I'll send you the relevant electrical diagrams by mail.

[majcd213]

Great please PM me for email. I have had a go at this and the results on my blog here https://majcd213.blogspot.co.uk/2017/10 ... otter.html let me know how it compares to your approach.
Thanks
Mike