I realized the Empeg FAQ that covers the hiJack options is missing the I2C fan control options.

They should be:

fan_control=1 (1=enable)
fan_high=## (in degrees celsius)
fan_low=## (in degrees celsius)

Where "high" turns the fan on and "low" shuts it off.

I don't know who maintains, so I thought I would ask if it would be worthwhile to add those to the FAQ?