Wiring an electric fan with override switch - guide

[alolympic]

I am currently fitting the alloy rad I bought from Dollyboy on here. I am refitting the same Pacet fan but having to use a new thermostat controller, because the other one stopped working for some reason.
I have been using a toggle switch on the dash to control the fan since the thermostat gave up, and I must admit I have got used to that now, and it actually is great for preventing the system getting too hot. Basically, as soon as you anticipate that the system could get hot, then you can switch the fan before it happens. Prvenetion is better than cure and all that.

I stumbled across this page recently, which I am going to follow for wiring in the fan with a manual override alongside the thermostat controller, as well as an LED light that will tell me when the fan is on.
http://www.trdrivers.com/fan.html

Thought it might be of interest to people on here if they wanted to tackle the same thing.
The only difference I am going to make is to connect the relay to the live circuit, rather than the ignition side. This is because I invariably have a hot end to my journey back to my lock up and I want the added advantage of the fan running to help the cool down process after I have switched off.

Maybe overkill for some people, but I like the peace of mind that this set up will give. I'm no expert as you all know, so if anyone knows of any flaws with following this set up then please let me know.

[Oli_88]

Al, you can get switches with a little LED bulb built in that turns on when the switch is depressed, you can also get the light to come on whenever the fan turns on without the switch too. I am also wiring my fan in to be permanent live, so it will run on a bit if needed.

Guide looks good (only skimmed it so far) however, I wouldn't use the ties that go through the radiator. On older rads they can shake and move around and ruin the rad. Putting some mounts on the frame instead is a better option. You're fitting a new rad anyway, so it might be ok, personally I'd still try and mount it to something more sturdy.

[alolympic]

Al, you can get switches with a little LED bulb built in that turns on when the switch is depressed, you can also get the light to come on whenever the fan turns on without the switch too. I am also wiring my fan in to be permanent live, so it will run on a bit if needed.

Guide looks good (only skimmed it so far) however, I wouldn't use the ties that go through the radiator. On older rads they can shake and move around and ruin the rad. Putting some mounts on the frame instead is a better option. You're fitting a new rad anyway, so it might be ok, personally I'd still try and mount it to something more sturdy.

Yep, my current toggle switch has an LED but I thought I would get confused if the same LED came on if the fan is on automatically or because I have switched. I'm even getting confused writing about it!!

No choice about the rad, unless I want to weld in new brackets. It did have brackets on it, to mount a fan centrally, but that wouldn't clear the alternator belt. Ties it will be, albeit 6, so I hope there is strength in numbers!

[alolympic]

Right, this is all done, ready for an MOT tomorrow.
The only issue I have, which is not critical, is that my LED Toggle switch is not illuminating when I want it to.
So, I have followed the diagram I attached before but have used an LED Toggle switch.
This switch has 3 terminals. I am connecting the switch to earth, the relay and the live side of the fuse box.
The switch operates the fan fine, but when the switch is on, the LED isn't. I can only get the LED to light when the switch is off, or not at all, based on swapping which terminals I am connecting the wires to.
I'm pretty sure now that it I have got switch wires going to the wrong place, rather than the wires being connected to the switch incorrectly, if you know what I mean.

Anyone help?
Cheers

[JPB]

Are you by any chance trying to do this with a 5-pin relay? If so, it's entirely possible that the feed from one to the other has been connected "always on" rather than to the neighbouring spade, which turns the load off when the switch is opened, IE is in its off position.

[Oli_88]

Al, is the switch the same as the one I posted on your thread on RR?
Robin seems to have explained it on there...
John, this is much the same as the question I mentioned last night. So I won't be posting it now!

[alolympic]

Al, is the switch the same as the one I posted on your thread on RR?
Robin seems to have explained it on there...
John, this is much the same as the question I mentioned last night. So I won't be posting it now!

Ah, apologies, I hadn't seen the most recent responses from last night.
I have now, but am still not clear.

[sprint95m]

Al, the illuminated part of the switch won't illuminate if you wire up as per diagram in the link
(because terminal 85 is the earth).
You need to run a wire from terminal 87 to feed the illumination, so it is better to use a warning light and ordinary
toggle switch instead.......
(Warning light is shown in the diagram to right of the switch).
Doing this will mean that the warning light will also illuminate when the thermo-controller switches the fan on.


I understand that all warning lights must operate properly for the new MOT (read this is Retro Cars).



Hope this clears it up.

[JPB]

Using 87A instead of 87 (or vise-versa) would have the same effect, which was why I asked whether you were trying to use a relay with five, rather than four connections.

[Carledo]

I understand that all warning lights must operate properly for the new MOT (read this is Retro Cars).



Hope this clears it up.

I think this only applies to things in the compulsory category like main beam, indicator tell-tales, rear foglight (1980 or later) etc and for stuff that doesn't apply to "our" cars like airbag and ABS lights. Steve

[alolympic]

Al, the illuminated part of the switch won't illuminate if you wire up as per diagram in the link
(because terminal 85 is the earth).
You need to run a wire from terminal 87 to feed the illumination, so it is better to use a warning light and ordinary
toggle switch instead.......
(Warning light is shown in the diagram to right of the switch).
Doing this will mean that the warning light will also illuminate when the thermo-controller switches the fan on.


I understand that all warning lights must operate properly for the new MOT (read this is Retro Cars).



Hope this clears it up.

Ah, I see. That makes sense.
I already have the warning light working fine. I just want the toggle switch to light up too, to make sure I don't just leave it on - especially as the fan is fed to the live circuit.

Using 87A instead of 87 (or vise-versa) would have the same effect, which was why I asked whether you were trying to use a relay with five, rather than four connections.

My relay has 4 connections.
So, if I get a relay with 5, and then connect as per the current, but with the toggle switch connected to 87A would solve the issue and give me a switch with working LED?
Please tell me yes, then I won't have to try everyone's patience any more - and I can pretend that I am helping Oli out at the same time.

[Oli_88]

Damn, caught me.
Think I have a 5 connection relay kicking about somewhere... Time for another extremely scientific battery on a bench, some clamps, some wires and a fan testing session!