Radiator Fan Switches.

Bit of info for the collective:

My van is a 2003 1.3 and I have had issues with, among other coolant related fun, a radiator fan which doesn't switch on.  I tested it by shorting the two terminals in the plug to be greeted with a whoosh of hot air coming from the environs of the radiator, which suggested the fan switch itself was suspect.  A quick missive to Woody of this parish soon had a switch of the correct vintage in a jiffy bag and on it's way to me.  Happy days.

The usually accepted switch has a M22 thread to fit the pipe.  Mine wasn't - it being an M18 so no way would it fit.  Here's a pic, the smaller one is mine:



Trying to get the correct switch has been a nightmare.  I'd tried the likes of Eurocarparts through to the old style motor factors with the dusty old parts catalogues without success.  I'd given up hope on finding the correct part so began to look elsewhere for a switch of the correct thread which I could use with modified wiring.  It seems that the M18 thread is not very common, the only other switch in M18 I found was from a late 90s Honda Civic, but it was special order only.  Hmm.

After a bit of hunting on the net I found out that a version of my vans switch was also used in a number Suzuki cars and bikes, a well as a Holden Barina from oz.  Important that.  It turns out that the switches for the UK spec Suzuki cars seem to use a higher temperature rated switch, 100/95 whereas the Holden version closes/opens at 95/90.  Arm with this knowledge, I tested my old switch in a pan on the hob and found it did work, on a very fast boil.  The larger switch woody supplied (marked 93/88) worked at a lower temp in the pan.  

Point of this post?  Apart from a second (third?) type of rad fan switch being available for later vans, the more common version in the UK is too highly rated for the application.  Coolant gets hot, fan doesn't kick in, van boils over and the owners starts down that well worn path.

Anyway.

Armed with a known good AC Delco part number, I phoned up my local parts place and found that they could get a switch in for a couple of quid, but it would be the higher rated one.  Same with a Suzuki dealer, but they wanted 33 quid ex vat.   In the end, ebay won out after finding the right one for £15.  Oh well.

Right, part numbers:

Valeo 7.5282.  This is the 95/90 switch and the one I'm trying out.
Valeo 7.5186.  Physically the same, but 100/95.

Cross reference it here: http://www.facet.eu/db_comp/catalogo/opencatalogue.asp

Other part numbers:

ECHLIN : FS154
AC DELCO : A1854
STANDARD : TS306
4 SEASONS : 36567
WELLS : SW1888
Tridon: TFS225

Link to a forum with the above (and more) part numbers and info: http://www.stromtrooper.com/v-strom-service-maintenance-questions-discussions/63617-radiator-fan-switch-17680-33e00.html

Nice research, thanks for sharing, will come in handy.

I actually have a tin full of sensors and switches including both types of fan switch.... so if you need anything else just ask! Hind sight I know now

The rule is pre 2001 is the big one, later vans which have 4 coil packs are the small radiator fan switch.

I would keep an eye on this situation, quite often when I've had vans which the fan doesn't kick in, it turns out the pipe it sits in doesn't get warm.

Then you have to ask yourself how many times in the past has the vehicle been left to spiral out of control on the temp gauge if the fan doesn't kick in.

And make sure you bleed it back up, and gently heat cycle it 3 or 4 times before you work it hard.

Switch fitted, coolant system bled and engine run up on the driveway. Drivers side rad hose warmed up then later the left hose flowed warm as the thermostat opened. No cold spots on the radiator that I could feel. The heater blew hot. The fan now kicks in at about 2/3rds up the temp gauge for about 10-20 seconds. I let the fan run twice, switched off and left it to cool. I checked the coolant under the cap below the passenger seat and added a small amount of coolant ~50ml.

I'll do the same again tomorrow to give it another heat cycle.

Excellent, next time drive it up the street, steer left and right harshly and some heavy braking.

Then cool it off, top it up again.

Next time take it for a drive.