[strictlypersonl]

The ERA is designed for the fan to run regardless of whether the ignition switch is on and the temperature in the bottom hose (where the thermo-switch is located) is above 175F. The fan will typically shut off after a couple of minutes if it is running when the car is shut off, which indicates that when the thermostat is open, there is some thermo-siphon action going on. That small flow (encouraged by the fan-cooled air in the radiator) keeps hot spots from forming in the block and heads. Therefore, post-shutdown boil-over is less likely.

Running the fan is also a small attempt to cool the engine compartment a bit after shutdown, which might help prevent fuel percolation during heat soak. Imperfect, but it might help a little. Running the fan for a couple of minutes is not a significant draw on the battery unless something else is wrong.