Auxiliary power unit and method for a vehicle

An auxiliary power system configurable within a vehicle having a main engine and a cab area, wherein cooled air is supplied within the cab using an air conditioning compressor within the vehicle, the auxiliary power system comprising:

• an auxiliary diesel engine having a power coupling, wherein the auxiliary diesel engine receives fuel from a diesel fuel tank of the vehicle during operation;
• a hydraulic power system coupled to the auxiliary diesel engine via the power coupling, wherein the hydraulic power system converts hydraulic power to mechanical power;
• a compressor drive mechanically connected to the hydraulic power system to receive the mechanical power;
• and
• an air conditioning compressor within the vehicle configured to receive the mechanical power from the compressor drive, wherein the air conditioning compressor is activated to provide the cooled air when the auxiliary diesel engine is activated.

A method for operating an air conditioning compressor in a vehicle having a cab and a main engine, the method comprising:

• activating an auxiliary diesel engine coupled to a hydraulic pump through a power coupling, wherein the hydraulic pump moves hydraulic fluid from a hydraulic reservoir;
• receiving the hydraulic fluid from the hydraulic pump at a hydraulic compressor drive motor;
• converting hydraulic power to mechanical power at the hydraulic compressor drive motor;
• providing the mechanical power from the hydraulic compressor drive motor to a compressor drive;
• and
• activating the air conditioning compressor by the compressor drive, wherein the air conditioning compressor provides cooled air when the auxiliary diesel engine is operating.