Radiator fan not running

Please move if this is incorrect location:

After upgrading the alternator and getting it running, I see that my fan does not come on. I put 12V direct to the fan harness and nothing. Is this common, or are they repairable at all? It spins easy enough but powering it up does nothing. Any Suggestions or experience?

Yuergen


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Re: Rad fan not running

Hi yuergenb,
This is Winston 66 from Western Australia.
All that I can suggest is that you check all of the plug in connectors that you might have disturbed (clean them)
The fan will not come on until the engine has come up to its proper operating temperature.
Let us know what you find.
Cheers , Winston 66

Re: Rad fan not running

The complete fan circuit is powered up at all times with the ignition key switch on. When at specified temp (205 degF), the fan switch closes and completes the circuit to ground, turning on the fan motor. You're putting 12 volts into a circuit that already has 12volts. With a test light or multi-meter, see if you have power going to the fan switch terminal with the ignition switch turned on. If so, put the fan switch terminal to a good ground and the fan should come on. So with this being said, if the whole circuit is being powered up with the ignition switch, and you put the fan switch terminal to ground and the fan comes on. Then the fan switch is no good, or the radiator is not grounded properly. Report back your findings...

Re: Rad fan not running

Thanks Guys. Will try these suggestions

Re: Rad fan not running

Make sure the radiator is grounded. I believe there is a ground wire that is connected to the radiator. The temp switch is mounted ( screwed into ) to the radiator. When the switch closes, if the radiator isn't grounded, the fan circuit will not be "completed" to ground. Make sure the radiator is grounded - use an ohmmeter to verify.

Re: Rad fan not running

So the fan motor runs and turns. I had read the instructions wrong on how to test it. it turns over when I put 12V to the right place. Now I am looking at either the thermo switch or cooling switch to see why it would turn on.

Re: Rad fan not running

Is there a way to test the rad cooling switch?

Re: Rad fan not running

yuergenb said:

Is there a way to test the rad cooling switch?

Click to expand...

By dropping it into boiling water?? ;-)
Its a standard 100?C ON device... (see other thread...)

Re: Rad fan not running

Jim Van said:

Make sure the radiator is grounded. I believe there is a ground wire that is connected to the radiator. The temp switch is mounted ( screwed into ) to the radiator. When the switch closes, if the radiator isn't grounded, the fan circuit will not be "completed" to ground. Make sure the radiator is grounded - use an ohmmeter to verify.

Click to expand...

+1 And let me expand on that post.

Got an Ohmmeter ?? Disconnect the two pin connector that goes to the fan. Check to see if the green wire is connected ( grounded ) to the chassis. Connect one of your Ohmmeter leads to the negative battery post and the other to the green wire. You should read real close to zero Ohms. If you have that reading, snap the connector back together and keep the one lead connected to the negative post of the battery, but switch the other lead to the body of the thermo-switch body ( the radiator, in other words). You should read real close to zero again.

The black lead at the fan connector should be connected to the radiator. My bet is that the thermo-switch is good, but you are missing a good ground at the fan. That would be the cheap fix, anyway.

If the green wire isn't grounded, you have a bad connection somewhere at the chassis, according to my schematic diagram.

Re: Rad fan not running

thanks will try that

Re: Rad fan not running

Back up and running. Replaced the thermo switch and sending unit. I also hardwired in a fan switch, just in case it goes on me while out riding, ever again. Thanks for the tips.

Where on the rad is the ground wire? I thought I fixed my fan not working asit was not plugged in. But it still seems to not be kicking in.

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StuartKeith said:

Where on the rad is the ground wire?

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There is a connector on the underside of the LHS frame tube, routing plus (to motor) and negative (back out) to the Klixon/thermo switch on the rad, which is "closing" to ground at >100?C...
Brief test: pull connector off the prong on the Klixon, push the rubber boot back and hold the crimp to a grounded point (like the hexagon outside/casing of the Klixon); with ign ON the fan should kick in.
If not, trace fuse and motor resistance.

Yes I've grounded this wire to the mana fold and it kicks in. But where is the rad earthed to the bike? Might take the heat switch off the weekend and try and test it.


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StuartKeith said:

But where is the rad earthed to the bike?

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Through the coolant to the engine block? ;-)

Low coolant level or Klixon/fan-stat defective... standard '90ies Honda Civic or Accura will fit...