Manual fan switch - just an idea...

[jeffsy]

Probaby been done before but...

Iv been having these problems with engine bay temperatures so I (well, not me obviously but Neil Garner) have just had the dashboard lights on off switch rewired so that this becomes a manual fan on/off switch. This way when I am approaching a town or am in slow traffic I can switch the fans on before the engine bay gets hot.

The dash lights switch (which is a little wierd to have if you think about it anyway) is now linked to the sidelights switch so that when they (the sidelights) go on the dash lights go on.

The fans are still controlled by traditional means to come on if I forget to press the switch, at whatever temperature they are set to (about 90 degrees for me). The only thing Im in discussion with/waiting for now is a ittle gizmo off Dave Beer to bring the fans in on a soft start rather than jump straight into full power.

On first showing yesterday they appeared to work well although I had to change the 15A fuse on the sidelights circuit to a 20A one. (and yes...I did that bit )

Graham

[AntonyJ]

It is a good idea, and as you say not uncommon.
Yours is obviously done now, but for other people.

The easiest way I found to do it was drop the fuse box out, find the wire that feeds the otter switch,link another wire to it and then feed the new wire to a switch (or use the dash lights switch) under the steering column.
All you need to do is earth the other side of the switch and its then brings the relay in , instead of the otter switch.

You could of course incorporate a "fan running" light somewhere into this.

[spend]

Override switch is always a good idea and should be std on all cars. Rather than having to short the otter switch you can quickly tell if any problems are due to a faulty otter switch (and even manually evaluate the effects of using one of a different rating).

A tell tale led is useful, but you want to know fans are being powered, even tri-leds can be used to show which fans are running. This feed can be taken from the fuse box as well. Be advised the fans act as generators in the airflow so you will need a resistor to the leds to stop them glowing falsely when you accelerate.

Having done all this stuff, I still maintain the most significant improvement (apart from good rad & pump) is to have the otter switch on the rad return. There are far too many spikes on the inlet side that set the fans off.

Dave

[350Matt]

spend said:

Be advised the fans act as generators in the airflow so you will need a resistor to the leds to stop them glowing falsely when you accelerate.
Dave

Aaaah my does the glowy LED thing

That explains it, I thought the otter switch was duff, how big a resistor? 40Ohm?

Matt

[spend]

Need to look at the spec of the LEDS you have used, they all seem quite different...

Dave

[GreenV8S]

If you feed the LED from the motor +ve and earth it via the otter switch/override you don't get the problem of motor back EMF lighting the LED when it's windmilling. It's just a matter of picking the right two terminals when you wire the LED into the relay socket.

Edited by GreenV8S on Saturday 30th June 20:29

[Pasco]

I had Carl Baker fit a fan over ride switch and a yellow light to tell me when the fans are on around two years ago and the good thing is that when the fans switch on in normal mode the yellow light also comes on so i know the fans are working

Top bloke is Carl and i am sure he will be at the Griff Growl 08


Keep up at the Back Welsh Singing Boy !! (When Pisse* in Coach)

Edited by Pasco on Saturday 30th June 23:45

[clive f]

pasco, YHM

[Pasco]

clive f said:

pasco, YHM

Clive i have no e-mail due to works server down since Wednesday night

I am not Joking dude!!

Land line playing up also

[Slacey]

Pasco said:

I had Carl Baker fit a fan over ride switch and a yellow light to tell me when the fans are on around two years ago and the good thing is that when the fans switch on in normal mode the yellow light also comes on so i know the fans are working

When I bought my Griff it had an override fitted with a yellow LED as you describe - I wonder if Carl fitted that one too? (the car came from down south)

[Pasco]

Slacey said:

Pasco said:

I had Carl Baker fit a fan over ride switch and a yellow light to tell me when the fans are on around two years ago and the good thing is that when the fans switch on in normal mode the yellow light also comes on so i know the fans are working

When I bought my Griff it had an override fitted with a yellow LED as you describe - I wonder if Carl fitted that one too? (the car came from down south)

Since Carl lives around the south coast i think you could be right mate

A very usefull mod imho and saves confusion with the light switches

[jeffsy]

Pasco said:

I had Carl Baker fit a fan over ride switch and a yellow light to tell me when the fans are on around two years ago and the good thing is that when the fans switch on in normal mode the yellow light also comes on so i know the fans are working

Top bloke is Carl and i am sure he will be at the Griff Growl 08


Keep up at the Back Welsh Singing Boy !! (When Pisse* in Coach)

Edited by Pasco on Saturday 30th June 23:45

...and he will be there in 07 too!!!

[Pasco]

jeffsy said:

Pasco said:

I had Carl Baker fit a fan over ride switch and a yellow light to tell me when the fans are on around two years ago and the good thing is that when the fans switch on in normal mode the yellow light also comes on so i know the fans are working

Top bloke is Carl and i am sure he will be at the Griff Growl 08


Keep up at the Back Welsh Singing Boy !! (When Pisse* in Coach)

Edited by Pasco on Saturday 30th June 23:45

...and he will be there in 07 too!!!

Dammm

[Griffit]

spend said:

A tell tale led is useful, but you want to know fans are being powered, even tri-leds can be used to show which fans are running. This feed can be taken from the fuse box as well. Be advised the fans act as generators in the airflow so you will need a resistor to the leds to stop them glowing falsely when you accelerate.
Dave

spend said:

Need to look at the spec of the LEDS you have used, they all seem quite different...
Dave

Any idea how to work out the size of this resistor anybody? I've tried wiring my fan light various ways but have never been happy with how it has worked. As such I'm back to using the fans power supply to power the LED and fear I will get the glowing without a resistor. My LED is 12Vdc type, RS components 207-860.

Thanks in advance

[spend]

As Peter mentioned you can also switch the -ve on the relay otter switch connection, which is OK except if you use tri-leds for 1/2/both fans where the logic fails

Dave

[Griffit]

spend said:

As Peter mentioned you can also switch the -ve on the relay otter switch connection, which is OK except if you use tri-leds for 1/2/both fans where the logic fails

Dave

Sadly doesn't work with my LED spec as this is how I originally wired it. When using the override switch I get a nice bright LED, however the otter switch doesn't seem to fully ground the circuit and I'm getting about 1.5V across it, thus the LED barely illuminates... Just tested for glow and am getting it about 60mph+ Could try a small potentiometer to work out resistor size I guess?

[spend]

Buy a strip of resistors & try different ones, IIRC 100ohm was what I used... but LEDS do seem to vary quite a lot in sensitivity - I think the quoted currents are for full light not seen what you have to keep them below for no glow at all .

Dave

[GreenV8S]

Griffit said:

Sadly doesn't work with my LED spec as this is how I originally wired it. When using the override switch I get a nice bright LED, however the otter switch doesn't seem to fully ground the circuit and I'm getting about 1.5V across it, thus the LED barely illuminates... Just tested for glow and am getting it about 60mph+ Could try a small potentiometer to work out resistor size I guess?

You're getting a 1.5V drop across the otter switch? You need a new one. No idea what you mean by 60mph+, just use a 12V LED i.e. one with an integral dropping resister.

[David Beer]

If you need an indicator for "fans on" it should not be on the fan supply. It should be on the relay trigger, ie otter, that way it will not glow at 55 mph. Personally i do not need an over ride, nor cardboard across the rad.

[Pasco]

David Beer said:

If you need an indicator for "fans on" it should not be on the fan supply. It should be on the relay trigger, ie otter, that way it will not glow at 55 mph. Personally i do not need an over ride, nor cardboard across the rad.

Is your car sorted now Dave ?