Bike getting hot cooling issue

Just throwing a thought out there, but did you try connecting the leads both ways to the fan?

Not sure on this model but some fans I've seen have a diode and will not run if the current is reversed.

That said, that's not too common so it does *sound* like possible motor trouble. Worth a shot though? If the motor isn't seized surely you could open it & test/fit new brushes rather than buying a whole new fan?

 

I think that's the other way round to be honest, a test lamp will require more current than a multimeter's volts setting will ever ask for & thus show up a weak circuit better than the multimeter...

The other side of that coin is that a multimeter will be able to show voltage drop through a bad circuit when it gets loaded up. So really a multimeter AND a test lamp are a good idea to be truly sure :wink:

 

Most people using a test light, only check to see if the light comes on and not how bright it is. That's why I always recommend a multimeter, so you can check volts and amps.