I need a chicken switch

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Sir Brixalot
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Re: I need a chicken switch

Post by Sir Brixalot »

Going to fit one myself. Driving up and down hills at weekend with heating on when the gauge began to creep up - 28c outside!
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937carrera
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Re: I need a chicken switch

Post by 937carrera »

I had never heard of a chicken switch until this thread, and have read with interest, to the extent that I have been reading the whole WBX wiring diagram, just for fun. :oops: http://syncrosport.com/info/wiring/VW_T ... _SP_DG.pdf

Terminal 30 is battery live (unswitched), and there are a number of connections from the fusebox to switches which are totally unfused (ignition, lights etc). Terminal 30 is also one of the fusebox feeds to some of the fuses. When you look at the wiring diagrams, the same fuse can have multiple thickness's of wire, according to the expected load on that part of the circuit, not just the combined load, which is what the fuse is sized for.

The fan is on fuse 1, set at 30A. I was further thinking about CovKids idea of simply providing the switching current to the original fan relay (which is what the mod is) and running cables all the way from the fusebox to the dashboard (considering RHD vehicles only).

Having looked at all the fused connections from terminal 30 the smallest fuse size is 15A, and perhaps the most convenient from a physical perspective is fuse 2 which provides power to the brake light switch (current flow 97) and brake lights. In theory only 42w or 3.5 amps of current required, let's call it 4 amps to allow for losses, efficiency etc. Then add 0.25 amps for the coil side of the fan relay.

From a physical perspective the wiring for the brake light switch is probably closer to where the chicken switch will be mounted, so a shorter wire run of 1.0mm wire to the switch (same as brake light switch) and then the other side of the switch to terminal 86, as Itchyfeet kindly indicated so graphically above. Thicker wire could be used if preferred.

There's usually more than one way to skin a cat, just chucking this in for consideration :) :!: :?:
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itchyfeet
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Re: I need a chicken switch

Post by itchyfeet »

Whats the obsession with minimizing wire size and switch rating, perhaps you save a pound or two, not everybody is looking to do it on the cheap
Go large makes it idiot proof and robust, in my experience small switches and wire get broken and damaged easily.

Yes there are many ways to do anything, I never said my way was the only way, it was what I did and I gave my reasons why I made those choices.

As you are quoting VW lets not forget VW used a 1.5mm2 red/blue wire to the relay coil ( see diagram above) so if it's what they did then why go smaller?
The reason you don't go smaller is fault current makes fires, if your badly crimped thin skinny wire falls off your cheap and nasty chinese 1A switch and brushes your dusty old steel dash you can have a 20A fault current that won't blow the fuse but makes smoke, up to you.

Perhaps others would like to take some time to document and photograph their methods?
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izzybarnard
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Re: I need a chicken switch

Post by izzybarnard »

I'll be getting the snips out and doing exactly as you prescribe duck. All seems 30amp sensible to me.
30amp rated Job done for 12 quid is a no brainer.

Thanks for the images and method description.

Cheers
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Re: I need a chicken switch

Post by crazyhorse »

Im with you itchy, thanks for making it as simple as can be. Got my 2.5 wire.

Located wires at fusebox, marked up. Waiting for my 30amp switch to arrive.
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ermie571
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Re: I need a chicken switch

Post by ermie571 »

30Amp switches ...tick
wago 222 connectors ....tick
red 2.5mm2 wire....tick

Haven't dived underneath yet....

Em
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captain Byrne
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Re: I need a chicken switch

Post by captain Byrne »

Sir Brixalot wrote:Going to fit one myself. Driving up and down hills at weekend with heating on when the gauge began to creep up - 28c outside!

Sure you don't have an underlying problem? I've driven up & down the Pyrenees in temps around the mid 30's, and when the gauge creeps up, the fan kicks in & cools everything down pretty efficiently. I've never had to put the heater on to cool the engine. Generally the needle stays in the middle unless I'm in standing traffic or going slowly uphill.

Whilst I think it's probably a good idea to fit a chicken switch, surely it shouldn't be necessary to use it unless the fan switch fails?
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itchyfeet
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Re: I need a chicken switch

Post by itchyfeet »

And while you petrol van lovers have your wire cutters and strippers out have you considered adding the fuses to the unfused circuits in the engine bay black box?

Ignition 12V Black and the permanent 12V stud both unfused :shock:

let me know if you want details.

never used my chicken switch yet.
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937carrera
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Re: I need a chicken switch

Post by 937carrera »

itchyfeet wrote:Whats the obsession with minimizing wire size and switch rating, perhaps you save a pound or two, not everybody is looking to do it on the cheap
Go large makes it idiot proof and robust, in my experience small switches and wire get broken and damaged easily.

Yes there are many ways to do anything, I never said my way was the only way, it was what I did and I gave my reasons why I made those choices.

As you are quoting VW lets not forget VW used a 1.5mm2 red/blue wire to the relay coil ( see diagram above) so if it's what they did then why go smaller?
The reason you don't go smaller is fault current makes fires, if your badly crimped thin skinny wire falls off your cheap and nasty chinese 1A switch and brushes your dusty old steel dash you can have a 20A fault current that won't blow the fuse but makes smoke, up to you.

Perhaps others would like to take some time to document and photograph their methods?

Itchy, I seem to have upset you for some reason, that was not the intention, and I don't believe I criticised anything you wrote, took a position that you said your way is the only way and made sure I recognised the photos you included, which provide your usual clarity.

I would suggest the reason why VW used a 1.0mm2 wire for the brake light is because of the lower fuse rating, i.e in their original design the factored in shorting concerns. The 2.5mm2 from the fan fuse carries 8A current for the motor. The second stage from the thermoswitch only carries relay coil current and could be thinner if it only takes 0.25A, BUT 1.5mm2 was selected by VW because of the 30A fuse

So, that's my explanation FWIW.

I thought I was clear that all I intended to do was to provide an alternative approach, and supported your view that thicker wires could be used if desired. If no one chooses to use it, that's fine with me.

I'm quite happy to have an exchange of views on forums, that's part of the reason they exist, and have learnt a lot over the years through them, but have no interest in flame wars, so if I have upset or annoyed you I'm big enough to say sorry :)
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937carrera
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Re: I need a chicken switch

Post by 937carrera »

captain Byrne wrote:
Sir Brixalot wrote:Going to fit one myself. Driving up and down hills at weekend with heating on when the gauge began to creep up - 28c outside!

Sure you don't have an underlying problem? I've driven up & down the Pyrenees in temps around the mid 30's, and when the gauge creeps up, the fan kicks in & cools everything down pretty efficiently. I've never had to put the heater on to cool the engine. Generally the needle stays in the middle unless I'm in standing traffic or going slowly uphill.

My thoughts too, second stage not working ?
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
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itchyfeet
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Re: I need a chicken switch

Post by itchyfeet »

I'm an electro mechanical development engineer I spend all day debating design choices and solving design problems, I don't get upset with different ideas and opinions, I'm happy to be challenged but I challenge back

no offence taken :ok
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Sir Brixalot
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Re: I need a chicken switch

Post by Sir Brixalot »

captain Byrne wrote:
Sir Brixalot wrote:Going to fit one myself. Driving up and down hills at weekend with heating on when the gauge began to creep up - 28c outside!

Sure you don't have an underlying problem? I've driven up & down the Pyrenees in temps around the mid 30's, and when the gauge creeps up, the fan kicks in & cools everything down pretty efficiently. I've never had to put the heater on to cool the engine. Generally the needle stays in the middle unless I'm in standing traffic or going slowly uphill.

Whilst I think it's probably a good idea to fit a chicken switch, surely it shouldn't be necessary to use it unless the fan switch fails?

Fan didn't kick in (and it does work as it kicked in the other day once I'd parked up) so I'm probably being over cautious but anything for peace of mind. It's an automtic which seeps a bit of power from the 1.9 - great on the flat and so easy to drive - not so great on steep hills. Very soon going to look at getting a 2.1 tin top as the kids are too big for us to all sleep in the van now, just need to sort a few things on my autosleeper first.
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937carrera
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Re: I need a chicken switch

Post by 937carrera »

It's a two speed fan with additional wiring to achieve the faster speed. It's quite possible for the low speed to work (like you observed when parked up), but for there to be a problem on the high speed side. You could be avoiding fixing an underlying problem by use of the chicken switch.

If you run a test wire to the wire connected to pin 1 on the thermoswitch (see the wiring diagram on the previous page), the fan should come on at high speed. (You could just bridge wires 3 and 1)

E D I T

Doh, or simply use your chicken switch :oops:

Assuming it works, which I suspect it will then you might want to test the operation of the thermoswitch, or start thinking about another underlying cause).
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

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itchyfeet
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Re: I need a chicken switch

Post by itchyfeet »

937carrera wrote:It's a two speed fan with additional wiring to achieve the faster speed. It's quite possible for the low speed to work (like you observed when parked up), but for there to be a problem on the high speed side. You could be avoiding fixing an underlying problem by use of the chicken switch.

If you run a test wire to the wire connected to pin 1 on the thermoswitch (see the wiring diagram on the previous page), the fan should come on at high speed. (You could just bridge wires 3 and 1)


This ^^^, test the circuit and change the switch if it does not work.



You can change the switch in minutes without draining the coolant, you just do it quickly and you loose very little coolant.

I just changed mine for a new Brickwerks one anyway as it looked original and I don't want the risk of it failing in France on my summer holidays.

When I changed it I found somebody had not replaced the boot so in time the contacts would have failed.

ImageP1080380 by Paul_Barr, on Flickr

ImageP1080384 by Paul_Barr, on Flickr
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itchyfeet
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Re: I need a chicken switch

Post by itchyfeet »

interesting the switch temps in Hanynes/ VW diagrams are different to the switch I bought, perhaps there is variation and thats why some peoples fans kick in later?

This from Brickwerks

Image2 stage fan test by Paul_Barr, on Flickr
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