An air conditioner system including a condenser fan, an ambient temperature sensor, a refrigerant pressure sensor, and a controller. The ambient temperature sensor is to sense ambient temperature at the system. The refrigerant pressure sensor is to sense pressure of a refrigerant of the system. The target refrigerant pressure module is to identify an optimum pressure of the refrigerant in the system. The controller is to generate an output representing a speed of the condenser fan operable to maintain the pressure of the refrigerant at about the optimum pressure as the ambient temperature of the system changes.