An air conditioning system for use in an over-the-road or off road vehicle
that provides operation during both engine on and engine off conditions.
The system includes a variable speed compressor, a motor, and a
controller. The controller receives electric power from the vehicle's
electric power generation system when the engine is on to enable
operation of the compressor during an engine on condition. When the
engine is off, the controller receives electric power from a battery to
enable operation of the compressor during the engine off condition.