I have had problems with my NC30 overheating and now going through everything. Coolant level is ok check. Thermostat removed as wasn't opening but not paying loads to Honda, rads checked clear and flushed loads. So here goes fan now off the bike along with bottom rad so can test the switch also. Have read the Haynes manual but thought to do it off the bike as easier. Connected the earth lead to the battery earth and connected a jumper lead to the +ve now i touch either of the spades or both? either way makes no odds as the fan don't do anything. So is the fan faulty or am I doing something wrong?

Any other ideas to check and reasons for overheating let me know as this is now getting to me

Leave it wired up as its supposed to be and earth the wire that connects to the fan switch, the fan should spin.

If it doesnt check for power to the fan, earth to the fan / radiator and lastly hardwire the fan straight to battery to isolate faulty fan.

So just get this clear in my mind. Reconnect the plug and remove the single spade connector and eath it out ie frame to the connector. I assume i should connect whilst ignotion off and switch on and check. Then remove once ignition turned off. Correct?

Yeah, plug the fan back in, rad on etc then just take that single spade off, and with the igntion on (bike running or not, your choice) just touch it to a metal bolt on the frame (earth) and the fan should go.

Cheers Neo will check when i get home from work and will update.

scotjell wrote:Cheers Neo will check when i get home from work and will update.

No worries, if your fan doesnt go you either have a bad earth or a knackered fan, in this case try wiriing the fan motor straight to the battery terminals and see if it runs.

However, if you try this and your fan does go but isn't comming on when the temp is in the red you either have a bad earth or a knackered fan switch.

Right fan checked and works. Only downside is wasn't sure before I cleaned the brushes and stuff. Next thing to check is the sender so best i get a thermometer from somewhere. If this proves to be ok also any more ideas as the only thing left on the cooling system is the radiator cap!

The fan wont come on until the needles nearly in the red zone.

I have a digital thermometer that I put on the radiator by the temp sender and monitor the temp, i think the fan comes on around 94ish.

If you have a multimeter you can check its working.

Put the switch in a cup of boiling water and measure the resistance from the spade to the outside of the temp.. if should be open (ie close to 0 ohms) when the waters boiling.. as it cools the resistance should go up to infinity (closed)

Any ideas where to buy a thermometer one that goes beyond 110 degrees C??