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MG Midget and Sprite Technical - Switching Kenlowe Fan

I want to abandon the temperature sensor and switch which at present controls/fails to control the operation of my electric fan.

I know that some of you prefer a simple switch on the dash, and that's the way I want to go. But I'm not sure how best to do it.

My car's positive earth, which presumably means that most of the switching is done on the negative side of the various devices. Would it be good practice to stick with that principle? It would mean completely re-wiring the fan, because at present it is switched on the earth side.

If the above hasn't revealed the fact already, I should tell you that I am electrically challenged.

Nick and Cherry Scoop

There's no reason why you can't switch to earth. Just use your dash switch in place of the temp sensor/switch.
Dave O'Neill 2

I think the wiper motor is switched to earth anyway!
Bob Beaumont

Nick,

I'm like you when it comes to that black art of electricity but as far as a fan goes, all you need to do is break the circuit some place so either place will work. I even figured out where to wire in an indicator light to tell me when the fan is on since I can't hear it when the engine is running.
Martin

That's a GREAT idea, Martin. It might be beyond me, though.

The existing switch I have is one of those little two-position pull switches. Do you think the demands of the fan might be too much for it? I once managed a relay for the hooter, so I think I could rise to that.
Nick and Cherry Scoop

If you install a relay you don't need to worry about the switch Nick. You can also buy very cheaply illuminated switches of various sorts. Push/pull, toggle, rocker - anything you like really - that will light up when closed to tell you the fan's on. Saves drilling a hole for a light. And the polarity isn't an issue as Dave said, as long as the fan's wired the right way round.
Greybeard

Im drinking greybreards and martians beer on this one....maybe even throw in an inline fuze

prop
Prop and the Blackhole Midget

Good call Prop. Inline fuse to the fan motor. Plus good call on the beer. Martin's closest - he can pay. Haha!
Greybeard

Nick
It doesn't matter whether you switch the battery supply (-ve in your case) or the earth side but, if you want a lamp, it would be better to switch the battery supply as the lamp can simply be connected via the fan feed terminal on the switch. If the switch runs hot you're better with a relay.
Bill
W Bretherton

I have a temperature switch in the head , and in parallel a toggle switch with an LED on the end of it on the dashboard.
Both switches are wired in parallel so that they can both operate the fan independantly.
I use a relay for the final power to the fan (actually i have 2)

The LED in the dashboard switch lights up to show the fan is working when it is switched by the thermo switch or the toggle switch.
Andy Phillips (frankenfrog)

Here's a pic of my dash. The red button in the center and under the dash is for my horn which is from some General Motors car since my standard horn always was erratic while the black button is the fan switch and the little light between the switches is the indicator light. They're mounted to a simple right angle bracket that is screwed to the bottom of the dash.

Martin

Hi Nick, I fitted (with help from bill sdgpm)a fan from a Maestro and removed the factory blades so I only run with the electic one fitted. You will gain a few bhp this way. Mine goes through a relay and I use a standard switch on the dashboard with a warning light. As I don't own as many brain cells as I used to I changed the oil/temp gauge for 2 separate ones, buying the mini style CNH full size temp gauge, so I can see it out of the corner of my eye creeping up towards H and brain then suggests I switch the fan on. Only had a few forgetful moments so far!! Good luck.
Geoff Mears

I fit a fan temp switch in the radiator just soldered a boss in works fine think its a 95° one
mark 1500 on the road Preston Lancs

Just to be different---
I had a fantastic run in my hillclimber/club car with the coolant sensor in the bottom tank of the radiator
It was a 50deg C on off switch type
Normal driving the bottom tank runs cooler than that but as soon as you get a lack of airflow, either from not moving or being close up behind someone else on comes the fan until you get some clean airflow
Works better than being in the top hose because the fan comes on earlier when it's needed BEFORE the overheating process has begun----
What do you reckon Prop
willy
William Revit

Ref the original post...why? If the thermocouple/sensor is kaput then simply buy another - cheap enough. Surely the whole point of such a set up is that the fan cuts in automatically, removing the risk of the frail human behind the wheel forgetting to flick a switch and cooking the engine. I agree that perhaps there are some cases where you would wish to override the sensor - manual and auto as it were - but surely not remove it altogether?
Oggers

Got to agree, fitting the sensing switch in the bottom tank or bottom hose works best.



Easy to fit one in the hose using one of these adaptors...............



http://www.carbuildersolutions.com/uk/aluminium-modular-inline-housing-32mm



I always finf the sort that slip into the hose with that rubber thing with the slot in, ie old type Kenlowe, are not easy to get a water tight seal with.



Mine's wired battery live and contunes to run after the key turns off, but not for long.



SR Smith 1

Hi Geoff - great to hear from you. What are you doing in Leicestershire?

I nipped into Hereford on Friday, and bought a relay from Halfords. The only ones they had were 4 pin 30A, and since I don't know what an amp is, I've got my fingers crossed.

To be honest, I'm fed up with the poor accuracy of the sensor and switch. I've got a three-row ali radiator which performs pretty well, unless you're in a very slow queue to get into Le Mans Bleu Nord Camping, and I've picked up the habit of looking at the temp gauge as part of the frequent instrument scan we all do.

BTW, it's my MGA I'm talking about, but I'd rather discuss it here because you lot are better.
Nick and Cherry Scoop

This thread was discussed between 30/08/2016 and 04/09/2016

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