Manual radiator fan switch.

[alfie1]

I have a manual rad fan switch in my van and as said previously, it is great for flicking on when you're slowing down to a traffic jam/queue, earlier than the fan would normally kick in. It alleviates a lot of panic when you look down and find that the temp needle has crept up to engine explode level.

My fan doesn't come on automatically though, think this one was just a quick fix job, but it works

It would work better if the engine worked and the van ran though

[Mr Bean]

I work in an aerospace organisation and keep on having top remind bright young engineers of the KISS principle. Without looking into it I suspect there are some electronicks involved in the fan system and so am aware that there is more to go wrong than a simple thermostatic switch. These are my views on the oil warning light system too. So who can blame anyone for installing a back up system for those times when reliance on this twenty year old bag of somewhat antiquated electronics feels a bit iffy?
Cheers
Wolfie
Keep It Simmple Stupid...

[A KIRK]

Off road vehicles often have a mannual switch for the Rad fans, but for the oppisite use to what most people would use them for. I lot of proper off roaders have them so they can turn the fans off if they are going through water, to save it throwing water all over the engine.

However in a T3 I fail to see the point of this as the fan is nowhere near the engine lol

[bigherb]

Radiator fan thermoswitches are notoriously unreliable. On many vehicles if used in rural areas the fans rarely operate as the forward motion of the vehicle is enough to cool it. In the winter the heater fan will return enough cool water back to the engine to stave off the radiator fan operating for long periods, even in build up areas. You don't really want to find out you fan is not working in the sixth lane queueing up for the Dartford Tunnel or in the middle of a motorway road works and by the time you've got the vehicle to safety you have cooked the engine. Fan switches are cheap engine rebuilds aren't.

[happy camper]

Radiator fan thermoswitches are notoriously unreliable. On many vehicles if used in rural areas the fans rarely operate as the forward motion of the vehicle is enough to cool it. In the winter the heater fan will return enough cool water back to the engine to stave off the radiator fan operating for long periods, even in build up areas. You don't really want to find out you fan is not working in the sixth lane queueing up for the Dartford Tunnel or in the middle of a motorway road works and by the time you've got the vehicle to safety you have cooked the engine. Fan switches are cheap engine rebuilds aren't.

Couldn't have put it better meself


We rest our case M'lud

[HarryMann]

Another, even lengthier discussion (and relay wiring suggestions for low current switching) here

[Titus A Duxass]

Radiator fan thermoswitches are notoriously unreliable.

Where are you sourcing your reliability information from?

[pionte]

The only time I have ever felt the need to add a over ride switch was on race cars....... I can only ever remember having one failure, and that was on a mk 3 escort XR3 that had had a very hard life ! It failed whilst on a trip so just bypassed the switch with a split pin untill I could fit a replacement.

I think that if it makes you sleep better at night then fit a switch, its your van personally I wont bother.

[bigherb]

Radiator fan thermoswitches are notoriously unreliable.

Where are you sourcing your reliability information from?

I worked for VW for 12 years and in the breakdown sector for 14 years and laterly teaching motor vehicle technology. I might have just got the jist of what goes wrong with them.

[Red Westie]

I have a similar background to you bigherb.....VW technician etc etc I've changed my share of faulty thermo switches but I still wouldn't call them 'notoriously unreliable' perhaps that they can fail so need regularly checking.
I conceed that many fail at vital moments ie: in a traffic jam on your hols etc but this can often be avoided with a simple check (desribed below) at important times.
ie: Done by allowing engine heat to rise (just let it idle for 10 minutes) in the spring/summer time and before a journey where you are likely to be caught in standing traffic or extreme driving of some sort.

They remain know more reliable or unreliable than any other switch or relay BUT with unfortunate catastrophic consequences if they do fail...
Mechanical switches and relays arn't the most reliable components when compared to inert parts like a bell housing or steering wheel but statistically they are probably more reliable than say a water pump or ignition switch.
All parts have a design life, thermo switches just like other moving/turning/switching components have gone at least 10 years past theirs.

Martin