Manual Fan Switch - Clarification!

[frodo_monkey 0]

I want to have a manual override switch for my fans so that I can have them running even with the engine off... So I searched and found (here) the following by Jonah:

 

1. Disconnect battery.

2. Pull the connector off the thermoswitch on the end of the rad.

3. There are 3 wires going into this connector (red, blue and white IIRC). About an inch from the connector, cut away a small section of the insulation off each wire, join a new piece of wire to it (best to solder the joint) and wrap with insulating tape. Making the joints close to the connector means they will be inside the rubber boot when it's put back together which will give them some weather protection.

4. Route the 3 new wires around the engine bay and through the bulkhead, making sure they are well secured to prevent chafing, and use a grommet where they pass through the bulkhead.

5. Connect the other ends of the wires to a heavy duty on-off-on switch mounted in the dash. Can't remember which wire needs to go to the centre terminal of the switch but it won't do any harm if you get it wrong, you just won't have the choice of low and high speed override. When it's connected the right way, the 3 switch positions will give you low speed, off, high speed.

6. Reconnect thermoswitch and battery. Job done

 

Which is great, exactly what I needed and I'll be off to do it tomorrow evening... But (you knew it was coming ) I only want an off/high speed override setting on my switch. So, which 2 of the red/white/blue wires do I need to run the wires off? I would look in my Haynes for guidance but its disappeared somewhere

 

Thanks!

[Higgy 0]

A few ways to do it I guess, but here is one.

 

Take off the connector from the rad fan switch, then using a short length of wire, bridge the pins (2 at a time).

 

Keep going until you hear the fan on its quickest speed. Then you will know which coloured wire to carry on with Jonah's instructions.

 

I did this, but a word of caution. You will need fairly heavy gauge wire. I used wire from a bedside lamp, and when the fan was running (it's a high amp drawing component) the wires got hot.

 

So I changed the wiring so that instead of going to the fan switch it went to a relay (which was rated for the amps drawn by the fan), so the relay activated the fan switch instead. This way the wires running into the cabin only have low amps going through them. Hopefully no chance of causing a fire.

 

Higgy.

[frodo_monkey 0]

Job done! For future reference, the wires are green/white/blue, and using green & white gives you fast (pins 1 and 2 in the connector) - I can't quite remember the colours (maybe green/blue) but pins 1&3 give you slow...

 

35A cable rocks

[shings 0]

why are you not using a relay for safety?

 

You will need a suitable switch and wiring which will take the current draw of the fans

[tom_m 0]

because you don't need too, as long as the appropriate gauge wiring is used and the correct amp fuse is installed its fine.

[DanS1982 0]

And the correct amp switch of course

 

I used a relay in mine

[shings 0]

And the correct amp switch of course

 

I used a relay in mine

 

Agreed- see you Sunday week Dan

[robgti 0]

sorry to bring this up again but where can i find a switch with the right amp rating? ive looked on ebay and found one thats rated at 25amps at 12volts. will this be ok? ive alright had one switch burn out so dont want it to happen again thanks

[VisaGTi16v 1]

Not sure but I took my dash out the other day in the Visa as one of my 2 switches had been playing up (one for fast speed, one for slow) and found the crimp on the end of the fast wire from the sender (not the 12v one) was black where it had got so hot and had partially melted the prong on the switch itself!

 

I have now put a inline fuse in and just rigged up one switch for fast speed on/off and will see how it goes, my switches are 25A. I put a 10A fuse in the fuse holder and it blew instantly, 15A works with a few on/off tests so will see how that goes, could probably do with some thicker wire if its getting that hot to show blackness on the crimp!

[SPGTi 2]

USE A RELAY

[robgti 0]

how would i wire a 5 pin relay for use with a switch to power the fans? any diagrams or pictures?

[jonah 1]

I'm sure that a 25A switch will be fine. The original fan wiring is not hugely thick, looks like standard 15A stuff, so the current draw can't be much more than that. The swtich I've got is not particularly big, it's probably rated 20A or so, and I've never noticed it getting hot. There were certainly no signs of overheating last time I checked it.

[pdd144c 0]

I usually use a relay and have the fan as a completely manual device. The dash switch is used to give a live feed to the coil input of the relay, and is then earthed on the output side. The contact side is then wired up somewhere on the positive side of the fan.

 

If you still want to keep the original switch in the rad just join the positive output from the rad switch wiring to the coil input of the relay.

[Guest larson]

how would i wire a 5 pin relay for use with a switch to power the fans? any diagrams or pictures?

 

if frodo_monkey is right regarding pin numbers and wire colors then the following scheme should work.

 

You should use automotive 40A 12V relay for the purpose.

Check terminal numbers on your 5pin relay, do you have 2x "87" terminals or "87" and "87a"? In case there is "87a" terminal then it is "change over" relay and you should leave "87a" unconnected.

In case there are 2x "87" then you can use only one of them or both.

 

 

Route thin (0.5mm2/20AWG) wire from relay terminal "85" to body or battery negative terminal or gearbox ground.

Install On/Off switch wherever you want inside the cabin. Since there will be little load on the switch you can use almost any switch.

Route 2 thin wires to the above: one from relay terminal "86" and another from permanent +12v source (battery positive terminal).

 

Install relay near the fan to keep thick high amp cables short.

 

Just check if you really need to bridge pins 1 and 2 on rad fun switch for high speed fan operation.

 

I hope someone can confirm this schema.

[Guest larson]

For manual only fan control you can use the following simple schema

 

 

I guess even 2mm2/14GA (25A) cable is sufficient for the task.

[robgti 0]

i see so i would only need a four pin relay? cheers for the diagram mate clearly explains it now

[GLPoomobile 958]

if frodo_monkey is right regarding pin numbers and wire colors then the following scheme should work.

 

You should use automotive 40A 12V relay for the purpose.

Check terminal numbers on your 5pin relay, do you have 2x "87" terminals or "87" and "87a"? In case there is "87a" terminal then it is "change over" relay and you should leave "87a" unconnected.

In case there are 2x "87" then you can use only one of them or both.

 

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Route thin (0.5mm2/20AWG) wire from relay terminal "85" to body or battery negative terminal or gearbox ground.

Install On/Off switch wherever you want inside the cabin. Since there will be little load on the switch you can use almost any switch.

Route 2 thin wires to the above: one from relay terminal "86" and another from permanent +12v source (battery positive terminal).

 

Install relay near the fan to keep thick high amp cables short.

 

Just check if you really need to bridge pins 1 and 2 on rad fun switch for high speed fan operation.

 

I hope someone can confirm this schema.

 

Can anyone confirm if the above diagram will allow manual switching for both high and low speed in addition to the orginal radiator mounted switch?

 

Also, would a fuse need to be incorporated at any point in the above diagram?

[Super Josh 4]

Can anyone confirm if the above diagram will allow manual switching for both high and low speed in addition to the orginal radiator mounted switch?

 

Also, would a fuse need to be incorporated at any point in the above diagram?

 

That schematic will only allow the switching of one speed, in this case the fast one.

If you keep the wires from the thermoswitch to the relay short, then you should be okay not having a fuse in that part of the circuit, as it is fused from the power distribution block on the slam panel. However, I would fuse the power wire to the dash mounted switch because that is direct from the Battery and goes through the Bulkhead (Firewall).

 

 

Josh

[Guest larson]

You'll need 2 standard relays then. Or some kind of double control and double output relay..

 

 

I assume here that green wire is fused feed wire coming from power distribution box. You can check this by checking continuity between battery (+) and pin on the termo switch before and after removing the fuse from distribution box.