brenin Posted March 26, 2013 Report Share Posted March 26, 2013 Hi All, the fan on my daughters 125 isnt coming on. We have only ridden the bike on about 4 occassions, and it has been v cold here in North Wales, but im sure there is something wrong. The fan can be spun readily by hand, so isnt seized. It doesnt feel tight or obstructed. There is coolant in the radiator, so the temp sensor must be seeing 'hot' coolant. Im looking for advice as to what order to check things. Is there a known problem with the fan? I was thinking of applying 12v dc to the fan to see if it spins. I guess the next step will be to find the temp sensor and check it hasnt failed 'open'. Im guessing a little bit of riding to get it hot will suffice, and then check its resistance? After that, im guessing, except maybe see that there is power to the fan when the temp sensor sees 'hot' coolant? Does anyone have any advice or experience with this? thanks Ian Quote Link to comment Share on other sites More sharing options...
jandyb Posted March 26, 2013 Report Share Posted March 26, 2013 Hi Try to connect the two leads to the temperature sensor together. If the fan runs now, its probably a faulty temp sensor. Quite normal... Could be some bad connections, so check that too.. If the fan still doesnt run, you could try appying 12v directly. -Jan Quote Link to comment Share on other sites More sharing options...
sting32 Posted March 26, 2013 Report Share Posted March 26, 2013 Hi All, the fan on my daughters 125 isnt coming on. We have only ridden the bike on about 4 occassions, and it has been v cold here in North Wales, but im sure there is something wrong. The fan can be spun readily by hand, so isnt seized. It doesnt feel tight or obstructed. There is coolant in the radiator, so the temp sensor must be seeing 'hot' coolant. Im looking for advice as to what order to check things. Is there a known problem with the fan? I was thinking of applying 12v dc to the fan to see if it spins. I guess the next step will be to find the temp sensor and check it hasnt failed 'open'. Im guessing a little bit of riding to get it hot will suffice, and then check its resistance? After that, im guessing, except maybe see that there is power to the fan when the temp sensor sees 'hot' coolant? Does anyone have any advice or experience with this? thanks Ian Jandyb is right, here's how you could try to trouble shoot it... I think the 05 has sensor in radiator top tank. there are 2 wires, the sensor is a "switch" that connects the 2 wires, make the circuit when warm enough water is found. It is possible for the thermo switch to fail, so we partially Test that out by taking it away from one of the reasons fan not working. find a spot to connect the 2 wires together, sometime just a Pin through both wire's protective covering does the trick. Start bike, fan should run, if not, then you have 2 more things to check... #1 fan, it is possible since it has brushes, for it to not run when getting power and ground (complete circuit). Try taking a 12v battery source touch juice from battery (using spare wires) to the fan's power leads, if you get the leads and battery backwards only thing will happen is fan goes opposite direction BTW. Once we know fan works or not, we can move on. If fan wont run off battery, fan has the problem. if fan runs, then you aren't getting juice to the fan for a couple of probable reasons; OR a third, being that your not getting a ground to the fan. The thermo switch is in the grounding circuit BTW, not the hot side. check your grounds first for dirty or corrosion, or bad wire at crimp on terminal connector connected to frame under the tank, usually (I think) shares the bolt on the Voltage Regulator. Now would be a great time to have a circuit tester, that measures OHMs or resistance. Resistance should be low from thermo to ground when water is hot. There are specs on this forum or on gasgas.com's site I believe, for checking resistance on the Voltage regulator part, but if everything is good (fan, ground, thermo switch) you might be able to assume the Voltage regulator is bad, or is also missing ground. To test thermo switch you have to test for continuity, when cool, it should be very high resistance (open), then place it into 180 degree (F) water on the cooktop, when thermo feels 180 or so (I guess within 10%) the resistance should drop to near or nothing (closed). if it doesnt, then of course thermo is bad. I had to change thermo in my 06 I believe after 3 years, that is only bike I had thermo problem (factory part), it ran several years after that with replacement. I have Never had the VR problem, yes I'm knocking on wood as I type... that is simple testing without many tools, there are people that can give you more technical steps, with better tools, hope that this helps... Quote Link to comment Share on other sites More sharing options...
brenin Posted March 26, 2013 Author Report Share Posted March 26, 2013 Hi Guys, wow thats great thank you very much! I will get onto that in the morning ;-) many thanks Ian Quote Link to comment Share on other sites More sharing options...
brenin Posted April 19, 2013 Author Report Share Posted April 19, 2013 Hi Guys, ok applying 12v to the fan in isolation causes it to run well. I have cleaned all the connections and earths that seem to be involved. The temp sender from radiator was showing infinite resistance with my ohm meter when the bike was cold. I have then run the bike and short circuited the connector that would go to the fan on the frame rail, thereby creating an earth. The fan ran. Does this mean that its purely a failed temp switch in the rad? I havent removed it, but it seems to be inset with a circlip holding it. Im assuming its fairly easy to change? thanks Ian Quote Link to comment Share on other sites More sharing options...
copemech Posted April 21, 2013 Report Share Posted April 21, 2013 Seems you are on the right track, however you did mention a few thinge that make me wonder, as you never mentiond overheating symptoms? If it is really cold out, a 125 does not(may not ) produce much heat to trigger the thermo switch just putting about. Specially if the rad is getting normal airflow! Prolly sitting stationary would kick it in after a while. Might try that, other wise the obvious true test on the thermo switch would be to put it in hot water while connected to meter. Just thoughts, carry on lad! Quote Link to comment Share on other sites More sharing options...
lineaway Posted April 22, 2013 Report Share Posted April 22, 2013 I think he answered his own question in his first sentence.`and it has been v cold here in North Wales` Basically you would have to ride the bike very hard to get the fan to run in cold weather. Quote Link to comment Share on other sites More sharing options...
seavoyage Posted April 22, 2013 Report Share Posted April 22, 2013 (edited) I replaced a seized fan motor (Daughters GG200) in November and a burned out Leonelli rectifier. 2-weeks ago (5-months later) fan stopped running.performed function test: 12V to (Blue and Black wires) fan = Motor not running. Replaced fan and Leonelli rectifier (Again). Fan did not work when engine running. Bypassed thermostat switch = No fan. Confirmed Leonelli rectifier is grounded (Yellow to Green wire grounded to bolt on coil); Has power (Yellow to Blue wire). Performed 12V test directly to fan = Fan does not run. Lesson Learned: Bench Test a brand new fan before installation. Edited April 22, 2013 by seavoyage Quote Link to comment Share on other sites More sharing options...
brenin Posted April 26, 2013 Author Report Share Posted April 26, 2013 Hi Guys, first off I'd like to thank everyone who has helped me with this problem, its now sorted :-) It had been cold, but i had also had overheating symptoms, with coolant blowing from the overflow on the pressure cap. It turned out it was the temp sender in the radiator. A new one and new circlip cost £40 posted and once swapped, the fan kicked in when the top of the radiator reached 60 celcius, so all is good. I did notice the radiator was marked KTM when i removed it, not sure if that means cheaper parts if i need them? I didnt try KTM for temp switch as if it was for a different spec motor then it may have different operating requirements.... many thanks Ian Quote Link to comment Share on other sites More sharing options...
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