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Fan Override switch wiring

tims31 - 19/1/15 at 11:09 AM

I know this is a subject that has been covered several times on here and the pros and cons of doing it but I have decided to add an override switch to my loom while I am doing the wiring.

Refering to the post by Snowy2 here I have used his drawing as a guide.

Description

The question I have is really as to the wiring of the override switch and lamp, I have done it this way to reduce the amount of wiring required and would just like it checked by the wiring experts on here that what I have done will work correctly.

Fan-override

gremlin1234 - 19/1/15 at 11:20 AM

the circuit looks ok, but the lower diagram shows relay contacts not the coil on 85/86

tims31 - 19/1/15 at 11:43 AM

Yep, your right.

I have adjusted it now, is this correct?

Description

loggyboy - 19/1/15 at 11:44 AM

Looks indentical to me.

tims31 - 19/1/15 at 12:05 PM

Changed the relay contacts on 85/86 to coil...

Irony - 19/1/15 at 01:32 PM

Can't remember the correct relay wiring numbers but I have wired mine so the lamp comes on when the fan comes on. It comes on both when when the switch is thrown and the thermostatic temp swicth turns the fan on. The theory being if the fan comes on whilst driving you can see that it has come on alerting you to a potential problem.

ken555 - 19/1/15 at 02:07 PM

fan

Works so the light comes on with the fan

Sorry only have paint handy

[Edited on 19-1-15 by ken555]

loggyboy - 19/1/15 at 02:23 PM

quote:
Originally posted by ken555

fan

Works so the light comes on with the fan

Sorry only have paint handy

[Edited on 19-1-15 by ken555]

I think the idea is the light warns you have overridden the thermostat, not to just tell you its on.

Trollyjack - 19/1/15 at 02:42 PM

I have a 2 colour LED when its energised by the temp switch its green
But if I override it it shows Red

[Edited on 19/1/15 by Trollyjack]

tims31 - 19/1/15 at 04:34 PM

quote:
Originally posted by Trollyjack
I have a 2 colour LED when its energised by the temp switch its green
But if I override it it shows Red

[Edited on 19/1/15 by Trollyjack]

So how does that work then, sorry but I dont know how that works, how is that wired up?

Ken555
I have updated the diagram as per your instructions.

fan-wiring3
The original way was to show when I had overridden the thermostaic switch but I suppose having it show when the fan is running would also be good, however if I could get it to work the same as Trollyjacks that would be great...so long as its not too complicated

[Edited on 19/1/15 by tims31]

ken555 - 19/1/15 at 04:55 PM

quote:
Originally posted by Irony
Can't remember the correct relay wiring numbers but I have wired mine so the lamp comes on when the fan comes on. It comes on both when when the switch is thrown and the thermostatic temp swicth turns the fan on. The theory being if the fan comes on whilst driving you can see that it has come on alerting you to a potential problem.

I was following this train of thought.

Warning it's on when moving, and warning it's over ridden.

I would have to work on the Bi-Colour Led version, as you need to reverse flow to make it work.

Trollyjack - 19/1/15 at 05:29 PM

Hi i use a switch on the dash that had double pole switch
Here is a photo of my wiring that shows the fan wiring

Description

tims31 - 19/1/15 at 08:08 PM

Err ok, really confused now with your diagram. Having looked up dual colour LEDs it shows them if current flows one way the LED lights one colour and another colour if it flows the other way, however your diagram using the double pole switch suggests that the current flows through it both ways whenever the switch is made. I could understand if it was a single pole switch as the current would flow one way when the switch was made and another way when the Thermo switch made...???

Sorry but just trying to understand this, does it need the double pole switch?

EDIT: Ok having looked at it again it looks like the LED you are using has three legs not two like the ones I was looking at, is that right?

[Edited on 19/1/15 by tims31]

Trollyjack - 19/1/15 at 08:52 PM

The light has 3 legs one is - the other two are + one lights up orange the other lights it up green when both are high the light is yellow

tims31 - 19/1/15 at 09:52 PM

Ok, So ive had a look at the diagram I used before, articles on three leg LEDs and refering to trollyjacks image.

I may be completely wrong but would the diagram shown below work to have the LED light one colour for the Fan running through the normal thermo switch and another running through the override switch??

Radfan3led

Having looked again it would be permenently on , time for a rethink..

[Edited on 19/1/15 by tims31]

Trollyjack - 20/1/15 at 08:58 AM

Cannot see that working why have you 2 earths on the led

Also I did not use a relay to control the fan

I used a fan swith of a polo and they dont use a relay.

loggyboy - 20/1/15 at 09:43 AM

Like this maybe - but ensure you have a shared cathode/negative bi colour LED
(ignore the warning lamp notation, I forgot to move it back!)

Fan Warning Bi LED

[Edited on 20-1-15 by loggyboy]

Trollyjack - 20/1/15 at 11:36 AM

Not sure if that would work you are using the led earth also to pull down the relay.

loggyboy - 20/1/15 at 12:37 PM

Assuming it was a 12v LED, should be fine.
Of it was a standard 2-3v LED then it would need a seperate circuit with extra relays or similar.

tims31 - 20/1/15 at 06:37 PM

quote:
Originally posted by loggyboy
Like this maybe - but ensure you have a shared cathode/negative bi colour LED
(ignore the warning lamp notation, I forgot to move it back!)

Fan Warning Bi LED

[Edited on 20-1-15 by loggyboy]

Ok I have tried again, just as a way of reducing another run of cable from the dash to the front of the car and assuming I use a 12v LED do you think this may work instead?

Description

loggyboy - 20/1/15 at 07:06 PM

quote:
Originally posted by tims31

quote:
Originally posted by loggyboy
Like this maybe - but ensure you have a shared cathode/negative bi colour LED
(ignore the warning lamp notation, I forgot to move it back!)

Fan Warning Bi LED

[Edited on 20-1-15 by loggyboy]

Ok I have tried again, just as a way of reducing another run of cable from the dash to the front of the car and assuming I use a 12v LED do you think this may work instead?

Description

That wont work, as you need to supply 2 dignals for the led, one from the thermostat and one from the overide, you can combine them.

snowy2 - 21/1/15 at 11:04 AM

In my article with the diagram it tells you how to wire it with the minimum wire.
the bulb will light whenever the fan is "on"

tims31 - 26/1/15 at 01:35 AM

I have had another look at trying to use a three leg/colour LED that will show a different colour depending on which switch is used, either the Thermo switch or the override switch.

Does this look like it would work this way?

Description

I know it is using another wire but I can run that no problems at the moment.

loggyboy - 26/1/15 at 08:32 AM

You have 2 unnecessary earth's, one to right of relay that will short past the led. And another to left of overide switch. Take those out and you have the same circuit I posted!

tims31 - 26/1/15 at 07:33 PM

quote:
Originally posted by loggyboy
Assuming it was a 12v LED, should be fine.
Of it was a standard 2-3v LED then it would need a seperate circuit with extra relays or similar.

Thanks Loggyboy, when you say a 12v LED, are there dedicated 12v LEDs or are they just normal LEDs with resistors to reduce the working voltage? Would the one atthe bottom of here be ok and would that work to pull down the relay?

I added the earths to the switches as I was concerend that if the LED was to fail then there would be no earth to operate the realy from either switch and the fan would not operate...

loggyboy - 27/1/15 at 10:33 AM

quote:
Originally posted by tims31

quote:
Originally posted by loggyboy
Assuming it was a 12v LED, should be fine.
Of it was a standard 2-3v LED then it would need a seperate circuit with extra relays or similar.

Thanks Loggyboy, when you say a 12v LED, are there dedicated 12v LEDs or are they just normal LEDs with resistors to reduce the working voltage? Would the one atthe bottom of here be ok and would that work to pull down the relay?

I added the earths to the switches as I was concerend that if the LED was to fail then there would be no earth to operate the relay from either switch and the fan would not operate...

Sadly those earths render the led useless and the current will never reach it. However you right in that the LEDs may restrict the relay from triggering, but without knowing the trigger voltage/currents of the relay, and the full spec of the diodes to run the numbers, the only way to ensure this doesnt happen is to use another 2 relays (could smaller surface mount ones) to trigger the LED.

snowy2 - 27/1/15 at 04:02 PM

Look its really simple....ANY SUITABLE AND CLOSE TO HAND 12V SUPPLY ........Under the dash goes to a switch the switched side goes to BOTH the LED (and then from the led to earth) and to the relay contacts (85)
from the fuse box a wire goes to the thermostatic switch ( AND Pin 30 on the relay) and then the other contact to pin 85 on the relay. Pin 86 to earth........pin 87 to the fan (s)
You only need one wire from the dash!

tims31 - 9/2/15 at 04:07 PM

Yes, thanks Snowy2. I did understand how to have it wired for just the single colour LED and for both the Thermo switch and override but was just trying to see if it was possible (or should I say easy enough) to do with a dual colour LED. It seems that I would be over complicating things and so will just go ahead with the single colour LED, just thought I would ask the question that was all...