Patent ID: 7448227

Claim:
A method of operating an air conditioning system for a vehicle having an engine to provide air conditioning to a sleeping area of the vehicle having an electric power generation and storage system, comprising the steps of: drawing electric power from the electric power generation and storage system when the engine is operating to drive an electrically driven, variable-speed compressor to cool the vehicle; drawing electric power from the electric power generation and storage system when the engine is not operating to drive the electrically driven, variable-speed compressor to cool the vehicle; disabling operation of the electrically driven, variable-speed compressor when an output of the electric power generation and storage system drops below a threshold; and determining a starting power requirement threshold of the vehicle's engine, and wherein the step of disabling operation of the electrically driven, variable-speed compressor when the output of the electric power generation and storage system drops below the threshold comprises the step of disabling operation of the electrically driven, variable-speed compressor before the output voltage of the electric power storage system drops below the starting power requirement threshold of the vehicle's engine.