We have used 40000 simultaneous ion temperature and drift measurements on Atmosphere Explorer C to study the ion energy balance in the high-latitutde F region. The large number of measurements allowed us to find how the mean ion temperature, and the average deviation from that mean, change as a function of ion drift speed during solar minimum conditions. We found that in spite of an apparent large scatter in the data, the measurements could always be reasonably explained in terms of fluctuations in the neutral dynamical properties, to which the ion energy is coupled. The results also provide evidence for increased neutral drift as the ion E¿B drift increases. Evidence for systematic ion drag effects can also be found, on the average, for dc electric fields stronger than 60 m V/m.