Patent ID: 7946123

Claim:
A system comprising: a compressor, a condenser and an evaporator connected in a closed refrigerant loop; a motor connected to the compressor to power the compressor, the motor being configured to operate at a first output speed to generate a first output capacity from the compressor and to operate at a second output speed to generate a second output capacity from the compressor; a control system connected to the motor to power the motor, the control system being configured to provide the motor with a first output frequency and corresponding voltage to generate the first output speed from the motor and the control system being configured to provide the motor with a second output frequency and corresponding voltage to generate the second output speed from the motor; a sensor to measure a parameter corresponding to an outdoor ambient temperature and to provide a signal to the control system with the measured parameter; and wherein, after starting the motor, the control system is configured to provide the motor with the first output frequency and corresponding voltage in response to only the measured parameter being greater than a first predetermined setpoint and to provide the motor with a second output frequency and corresponding voltage in response to only the measured parameter being less than or equal to a second predetermined setpoint.