Hey if anyone has had a problem with the fan and fan switch not operational, you might want to take a look at the grounding for these units. I have a project bike, which was not taken care of by the previous owner, which I am using as my Track bike. What I did was I added an additional ground going directly to the aluminum frame. Maybe this has already been covered on this Forum...but I thought I would throw it out there.

 

The only time I see single wire temp switches not have a good ground path is when someone mistakenly uses thread tape or other non conductive sealants to install the switch. But for sure a secondary ground is not a bad idea.