the fans can be loud, and annoying... mine is under the bed in the storage bay and we can also hear it easily... when the temperature is higher than 80-85 degrees, most will run the fan... at least until the temperature around the inverter/charger is back to below those numbers...
if the inverter is working, while you are not on shore power, then the fan may come on to cool it down
if the charger is working, while you are on shore power, and it is in bulk charge mode, it will also run
'14 Palazzo 33.3 bunkhouse 34' diesel
KingTailgater2 Dish HD, 100w/5a SOLAR, BlueOx
100,000+mi since '14 - US, Alaska, Canada - Northwest, GA! (also, '14 Gulfstream Amerilite and '07 ForestRiver Rockwood) : )