Nighttime Ventilation questions for newbie..AC or Fan?

Our WhiteHawk only had one exhaust fan, the cheap buzz saw fan that was the OEM installation in the bathroom. We paid the dealer to replace it with thermostatically controlled Fantastic model and a Maxx Air vent cover. It does a great job with temperature control night or day when air temps aren't warm enough to require AC. With one window opened slightly to draw in outside air with the fan, we're pretty comfortable. Only potential downside is when humidity levels are up, in which case we go with the AC.