The fan on the left is for the A/C, the one on the right is for the motor, this is the important one. I believe someone previously mentioned checking the sensor, I would try this also. There is 2 of them, one for the gauge and another for the fan.
Originally Posted by
martinjsxx
Today the fan has not come on, but I don't know if/when it will happen. If it is a short, why wouldn't it occur all the time?
Because it may not be a dead short. It could be a damaged spot in the wire insulation that is grounding out occasionally.