Is he taking it out directly from a warm place (heated truck) into the cold? The way that I understand it is that the greater the temperature difference between the unit and the environment the more often it will NUC until the two temperatures somewhat equalize. I leave my NOX in my truck in an unheated garage and I don't have to NUC it very often at all. I leave my Halo in a box in the bed, I NUC on startup and rarely NUC again during a 20 minute stand.
If it is auto NUCing nonstop and it is close to the same temperature as the environment there is a problem with it and it needs to be sent in and diagnosed..