A generator set for a transport climate control unit is provided that is operable at a first frequency and a second frequency. The generator set includes a generator, a prime mover configured to operate at a first non-zero speed and a second non-zero speed that is less than the first non-zero speed, and a genset controller configured to control operation of the generator set. When operating at the first non-zero speed, the genset controller is configured to monitor a prime mover load parameter to determine whether the prime mover is approaching or has exceeded an overload or stall situation. The genset controller is configured to reduce the speed of the prime mover from the first non-zero speed to the second non-zero speed to prevent the overload or stall situation.