thermo switch - fan kit.

finally had a chance to install the new thermo switch ( Beck/Arnley 2011310 switch which is a 95C/91C) tonight along with a trailtech thermo gauge.

Gauge is on the hose coming off the return of the head maybe 3-4 inches up just before the thermostat

I nervously watched the Gauge climb to 210+ thinking damn something must be wrong!

But @ 215 the fan finally came on, woohoo

This was just idling in the driveway, and it didn't really come down at all, but i'm sure with movement this will be perfectly fine.

Looks like my thermo switch is gone again

Same symptoms as before, fan doesn't come on, but if I jump it across the terminals it spins up.

Anyone know of some possible reason a thermo switch unit could go out so fast?

I replaced this around 25 hours / 1000 km's of use ago. Thinking I should order 2 this time so i have a spare

Has the thermo switch been frozen???

Ordered 2 units from thewrenchmonkey.ca, 20 bux each so at least i'll have a spare on hand this time!

I've ridden in the winter with this last thermo and my timberseld snowbike kit installed, but it's never been left outside overnight or anything.

I'm heading outta town for business for a week, new switches should be here when i'm back and i'll get it installed asap.

bumping this... so my order got cancelled, and i had to source one from a local place (also had to order them in).

yesterday I was out riding and the switch is dead again. I can jump the pins and the fan comes on, so all the wiring/fuses are good.

this is now the 3rd thermo switch that's died on me in 2 years... wtf am I doing to kill these things?!

i'm going to hardwire a on/off switch inline so at least i have a manual backup.

Yes you can jump the pins, this is where you would hook your fan switch to

I would also look at a plugged rad as a air pocket will prevent coolant from hitting the thermos switch and making it come on. Take the switch out and put it in boiling water and see if it is working as it does sound funny that your going through switches. Are the rads low? where is the switch mounted? Lower part of rad of upper?

I had just put the bike back together several weeks ago and based on having so many fan issues, I purposefully let it run upto temp to ensure the fan kicked in.

And it did.

I've had 3 rides since then and just noticed this past ride that it was no longer triggering the fan.

I did have to leave the bike outside over night in the rain prior to this last ride, but no idea why that would kill the switch.

I'll try the boiling water idea and see how that goes. I assume I need to use a multi meter to measure it somehow?

Thanks for the help FE!

Rain/water and a electric switch not a good combination. At the very least Dielectric Grease on the switch or seal the switch some how.

jeffk95z said:

I had just put the bike back together several weeks ago and based on having so many fan issues, I purposefully let it run upto temp to ensure the fan kicked in.

And it did.

I've had 3 rides since then and just noticed this past ride that it was no longer triggering the fan.

I did have to leave the bike outside over night in the rain prior to this last ride, but no idea why that would kill the switch.

I'll try the boiling water idea and see how that goes. I assume I need to use a multi meter to measure it somehow?

Thanks for the help FE!

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The rain in no way will cause a problem with the switch as it is sealed and a low voltage switch. Even if the water shorted the switch all that would happen is the fan would come on. It is a motorcycle designed to get wet
I however would not submerge the bike, but mine has been many times without incident.

You have heard of corrosion? Overtime. On this Forum people ask about electrical problems and water rain mud are reasons sometimes. Sometimes it's better to fix a problem before it starts.

Yes Rainerio that is correct for sure, but finding the reason the problem exists is the first step, then correcting it. If the problem is from corrosion then he will need to fix that area. He mentioned that shorting the wires together runs the fan so I do not think it is a corroded wire but more a switch issue or an issue with the switch no touching the coolant thus coming to temp and switching on.

i havn't had a chance to do much with this yet, but I did check coolant level tonight, its just above the fins - I think thats the right level?




Will boil/check my old broken one (kept it) and this latest non-functioning one asap.

Also get a manual toggle switch wired up

Thanks for the replies and suggestions!

I had car door switch go bad. Took 13 years for it to fail from rain and it's inside the car why did it go bad corrosion/oxidation. Granted it's not heat related like temp. Sensor but still no good at wire contact points. Anyway my fix is new switch with Dielectric Grease should be fine.Time will tell?

Rainerio said:

I had car door switch go bad. Took 13 years for it to fail from rain and it's inside the car why did it go bad corrosion/oxidation. Granted it's not heat related like temp. Sensor but still no good at wire contact points. Anyway my fix is new switch with Dielectric Grease should be fine.Time will tell?

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He has replaced the switch 3 times. I somehow don't think in the last six months the corrosion is that bad that he requires three thermo-switches????????? Just a thought from an automotive/motorcycle electrical technician???
Trying to help him out with my years of knowledge is all. He needs to isolate the issue is all. I am doing my best helping him online with what I can

I'm not saying Your help is wrong FE350 just throwing out possiblies. It's not just for jeffk95z it's for anyone reading this thread.

There is another possible cause. Perhaps the current is too high and switches are just burning out. Wire in relay. Use switch on signal circuit and fan on power side. Hook up power to 30 and fan to 87. Hook up switch to 85 and ground to 86. This might help you. Any regular relay good for 30 amps.

polska said:

There is another possible cause. Perhaps the current is too high and switches are just burning out. Wire in relay. Use switch on signal circuit and fan on power side. Hook up power to 30 and fan to 87. Hook up switch to 85 and ground to 86. This might help you. Any regular relay good for 30 amps.

Click to expand...

Very good point as most thermos switches will be 12v or 24v application specific. Amperage is good on most between 25 to 50 amps.

Is this a factory hook up or did you add this in. Is it hooked to your headlight circuit? Or is it hooked directly to your battery?

If it is direct to battery you will only need a fuse and nothing more. If you have it in line to your headlight it might have AC voltage running through it and this could cause an issue as it requires DC voltage and voltage that does not spike big ranges.

The relay idea is great but will not change voltage and or reduce it in any way. It will stop from breaking down a circuit on a light wire application and if the harness was designed as a fan circuit it will have 18 or better gauge that will be more than sufficient for this application. I assume that the circuit is still good when you short the wires together the fan runs.

Easy way to check this circuit. Run a volt meter and check for AC or DC voltage and high spikes above 15V. If the voltage ramps hard on throttle and above 15v than it just might be on the wrong circuit and or a bad regulator. Stators put out AC and DC voltage to your system, little more complex that that but making it simple. Voltage regulator stabilizes the DC voltage to charge your battery. Lighting coils can produce AC just to the headlight. Back in the old days our bikes would have dim then bright lights upon rpm. These were AC lighting circuits for the headlights.

Just some food for thought.

I haven't done it yet. But if I do then I would either use factory hook up for relay swith side and just run power wire from battery to power side of relay then to fan and to ground. Or I would be looking for ignition dc power source for the switch side of the relay. I'd try to stay away from ac voltage.