Patent ID: 7266961

Claim:
A mobile refrigeration system comprising: an engine operable at a first speed and a second speed; a compressor operable in response to operation of the engine to produce a flow of compressed refrigerant; a valve associated with the compressor and movable between a first position and a second position to vary the flow of compressed refrigerant; a fan operable in response to operation of the engine to produce a flow of air; a first temperature sensor positioned to measure a first temperature; a second temperature sensor positioned to measure a second temperature; a timer operable to time a duration; and a controller operable to vary the valve position to maintain the first temperature at about a user set point, the controller also operable to transition the engine between the first speed and the second speed in response to a measured first temperature in excess of a first predetermined value and the second measured temperature less than a second predetermined value and a timed duration greater than a predetermined time.