On 6/23/2012 5:24 PM, Bill M wrote:
> I have one of the fan switches that kicks the fan on lower
> than the stock switch is factory spec'd for.
>
> Bill -whose fan runs more than needed...

Sounds like it's too close to the thermostat temp. When the T-stat
opens, and lets more hot coolant through the system, the fan kicks in,
and the combination cools quickly. Lather, rinse, repeat. Doesn't really
hurt, but unnecessary wear and noise.

Fan T-stats need to be enough above the coolant T-stat to let it do it's
job. They shouldn't kick in until the coolant T-stat is fully open,
except A/C ones, which are to cool the condenser, not the radiator. But,
those are usually run continuously when A/C is on, so they don't cause a
feedback loop.