anyone fitted a radiator fan switch?

[Doctor Foster]

Want to fit a manual radiator fan switch on the dash. Is it an easy job??

[famous phil]

Hi, Yes I just soldered new wires T'd into the fan temp switch sensor wiring on the radiator and ran the new wiring up through the rubber boot behind the headlamp to behind the dash ,,,, I'm not sure if you could just connect up to the wiring behind the fuse box or a relay on the later campers

Regards Phil

[Doctor Foster]

Hi, Yes I just soldered new wires T'd into the fan temp switch sensor wiring on the radiator and ran the new wiring up through the rubber boot behind the headlamp to behind the dash ,,,, I'm not sure if you could just connect up to the wiring behind the fuse box or a relay on the later campers

Regards Phil

Thanks Phil. Will give it a coat of looking at this weekend

[famous phil]

I helped a mate out on the way into a show and his campers rad switch was thought not to be working and as a temp ( no pun intended ) measure I made up a quick bypass two male spade connectors attached to two inch of cable ,, unplugged the plug from the rad and put the connectors into the plug so that the low speed came in on the fan

[Doctor Foster]

I helped a mate out on the way into a show and his campers rad switch was thought not to be working and as a temp ( no pun intended ) measure I made up a quick bypass two male spade connectors attached to two inch of cable ,, unplugged the plug from the rad and put the connectors into the plug so that the low speed came in on the fan

How easy is it to get to the plug??

[famous phil]

Hi, if you remove the lower grill it should be on the nearside , feel round the side of the radiator ,, saying that you should be able to see it

[big red bus]

Can I just ask why you want to do this. If the motor is working as it should and everything is operating o.k then you should not need a manual by pass switch. Would it not be better to sort out any problem you may have so the system works as it should.
But yes easy to do, if you have three pin connector then you have 2 speed fan. 2 pin single speed, just put a fuse in the wirng and wire it up o a toggle switch some where at hand.

[Doctor Foster]

Can I just ask why you want to do this. If the motor is working as it should and everything is operating o.k then you should not need a manual by pass switch. Would it not be better to sort out any problem you may have so the system works as it should.
But yes easy to do, if you have three pin connector then you have 2 speed fan. 2 pin single speed, just put a fuse in the wirng and wire it up o a toggle switch some where at hand.

Nothing wrong as far as I am aware. Just fancy fitting one for when Im in slow moving traffic.

Found another thread https://club8090.co.uk/forum/viewtopic.p ... n#p7450513" onclick="window.open(this.href);return false;

[clartsonly]

put the heater on instead the fan will cut in when it nbeeds to...

I have done this on the fiat cinqcento but that is because the head gasket hgas already been replaced and the fan doesn't cut in until about 110c which is too hot for that little car. remember when you forget to switch it off the battery will be flat.

[tencentlife]

Can I just ask why you want to do this. If the motor is working as it should and everything is operating o.k then you should not need a manual by pass switch. Would it not be better to sort out any problem you may have so the system works as it should.
But yes easy to do, if you have three pin connector then you have 2 speed fan. 2 pin single speed, just put a fuse in the wirng and wire it up o a toggle switch some where at hand.

Nothing wrong as far as I am aware. Just fancy fitting one for when Im in slow moving traffic.

Found another thread https://club8090.co.uk/forum/viewtopic.p ... n#p7450513" onclick="window.open(this.href);return false;

I was going to offer some sound rationales but the thread linked-to covers the reasons. Myself, we live in the Rockies and often spend half an hour or more at a stretch slowly climbing in low gears up rough dirt forest roads. We'll gain two or three thousand feet of elevation without a break, it's a lot of work the engine is doing. The OEM thermoswitch works just fine, never ever overheats (but then, in even decent trim, this cooling system is actually very powerful despite what all the nervous Nellies say). But, the system can't think ahead, and I can; when I know the grade is going to be long, I can flick my little dash switch and guarantee the engine a supply of nice cool water to use as it needs.

The ideas in this thread, though, go at it with a 6-pound hammer, intercepting the heavy current wires right at the thermoswitch is crude, expensive, and prone to failure. What you want to do is use X-bus power and apply it to the fan relay, and let the relay switch the heavy power because it's already there to do just that. That means you can use very light wire, a tiny, cheap switch, and do all the wiring right in the dash without having to route anything at all thru the firewall. Using the X-bus means that the fan only runs when the key is on, and is killed during cranking so as not to rob power from the starter circuit. It doesn't matter if you forget and leave it on, it can't kill the battery unless you leave the key on, too.

The switch I use is a tiny little rocker bit with a nice bright-blue LED in it, so even in daylight I'm aware that it's on (witness the unblinking eye of doom):


Exactly which way to go depends on your year/model and whether or not you have AC. Most of the late vans in the US have AC, so we get the big 450w fan with three speeds. If you have this, the low speed can already be activated by just switching on the AC; leaving the temp dial at its very lowest will cycle the compressor almost not-at-all, but the rad fan runs constantly. If that's not enough cooling, the rad thermoswitch will still jump in and override it with the higher speed if needed.

My extra dash switch triggers the 2nd speed relay, like this (Bentley p.97.141):

This can be done all right on the back of the fuse panel, you can get X power off of G1 or G3, and tap into the T-shaped brown H-plug that services the rad fan relay. Then you just need to run two very light wires to wherever you want your switch mounted to complete the circuit.

Here's a handy list I have of the available extra connections on the back of the late fuse panel (sorry you all who have early stick fuses, you'll have to muddle thru this yourselves, I just don't have such neat data on them because the book is not so helpful):

This applies to the late, '86-on fuse panel only:

When you want a power supply for something, there are unused pins on the back of the main relay panel for most anything you'd need. On the left end (installed position), there are 6 pins in two rows labelled "P". These are all #30 pins, battery direct, unswitched, unfused. They are good for fairly heavy consumers. At the other end are ten pins labelled "G". These are hot under various conditions and can be used to power accessories. You can patch into the panel at whichever pins do the job for you by just plugging on a female spade terminal. It is always advisable to use a fuse inline from any power source to protect your device and wiring.

I'll list them according to the diagram. Where power is via a panel fuse, I've noted that with the letter "S". Always verify with a testlight or VOM before hooking up:

G1 & G3- X-bus load-controlled power (hot when ign. on, goes cold when starter operates) via S12
G2 & G5- #15 ignition-switched power via S18 (this is the ideal power source for extra instruments)
G4- D+ (alternator trigger circuit) via alternator warning LED
G6-dead end
G7 -headlights power
G8 -dimmer-controlled panel lighting power (to light your extra gauges)
G9 -parking lights power via S20 (for your low-rider under-chassis lighting, ese!)
G10- hot when windshield washer pump runs (headlamp washers, anyone?)

Earlier panels with stick fuses may also have extra power pins on the panel. You can check with a testlight or VOM.



Here's the skiz to trigger the 2nd speed fan relay on a late non-AC van (p.97.99):

That is the high speed on the two-speed fan motor, though, which might be too much for some to leave on for long, but it would provide pretty quick cooldown.

Triggering the lowest speed on an early or non-AC van is a little harder, because the rad thermoswitch powers the fan directly without an intermediary relay. If I wanted to do that, though, I would still add my own relay nearer the fan itself, and run the small triggering wires and use a small switch up on the dash rather than having to run heavy wire and a bigger switch.

Hope some of you find this info useful.

[AngeloEvs]

E D I T. Posted reply just after previous reply was posted.......but will leave as is......thinking pretty much the same.

You can take a feed from the ignition side of the fuse box, via a switch to the coil feed for the rad fan relay (terminal 86) colour coded R/Bl behind the relay......pretty sure thats how I did mine but its been a while. .....useful for checking every so often that the fan actually works OK!

I remember getting a real lambasting for doing this from the guys on Brickwerks some years back.......modding a VW doesn't always go down well but, what the hell.......it's my bloody van! Went up Porlock HIll and the fan didn't come on ......earth spade had overheated and crumbled away (at the crown next to the fuse box) and hadn't been aware of it. I see a big hill looming and I flick the switch.......just to make sure......

Easy enought to do which ever method you use but don't try and feed the Fan directly using a switch......it will be foobarred in no time at all.....take a fair bit of current those Rad Fans!

[tencentlife]

take a fair bit of current those Rad Fans!

Yeah, that's the whole point. And the switchgear is already in place to handle it, so it's smarter, cheaper, and more reliable to just use the highway you already have rather than building a new one.

I remember getting a real lambasting for doing this from the guys on Brickwerks some years back.......modding a VW doesn't always go down well but, what the hell.......it's my bloody van!

That's also exactly how I feel about it, I have no patience for old ladies telling me I can't do a better job than VW. Of course I can, I have twenty years of hindsight on what they did that worked and didn't work.

[Doctor Foster]

Oops Have I opened a can of worms here.

[AngeloEvs]

No.. ..there's a few on Club80-90 with manual switches......(don't ask on the 'Brickies' site tho'.......which is kind of odd considering that its ok to fit Porsche allys, Suby engines, 1kW bass boomers, etc)........who cares anyway.. it only a friggin' switch!

[bigherb]

Like I said in the other thread it's not much good finding out your thermoswitch isn't working when the engines boiling and can't do anything about it.
Good idea tencentlife but a lot of UK vans are only fitted with a single speed fan without a relay, which are even more susceptible to failure without the backup of the second high speed switch contact.