Abstract: A refrigeration system for a mobile unit and a method for operating the same are provided. The method includes the steps of: 1) providing a refrigeration unit having a compressor, an evaporator, and at least one fan operable to move air towards the evaporator, a generator dedicated to the refrigeration unit, and a battery; 2) determining at least one environmental parameter in one or both of the mobile unit and the refrigeration unit; and 3) selectively operating the refrigeration unit in one of a plurality of modes based on the environmental parameter, which plurality of modes includes a first mode wherein at least the fan is powered by the battery, and a second mode wherein the compressor and the fan are powered by the generator.

Abstract: A refrigerant system capable of operating at multiple capacity modes includes an evaporator, a multi-stage compressor assembly, a first fluid flow path, a second fluid flow path, a first valve, and a second valve. The multi-stage compressor assembly has a first stage and a second stage. The first fluid flow path extends from the evaporator to the first stage of the multi-stage compressor assembly. The second fluid flow path connects to the first fluid flow path and to the multi-stage compressor assembly between the first stage and the second stage.

Abstract: An apparatus and method are disclosed for terminating a refrigeration unit's defrost function. The refrigeration unit comprises an evaporator, a temperature sensor to measure the temperature of the evaporator during a defrost function, and a controller configured to calculate the rate of temperature change and terminate the defrost function when the rate meets a specified criteria, such as a predetermined rate or a sharp increase in the rate after the evaporator temperature has increased above the freezing point of water.

Abstract: A plurality of resistance heater rods are assembled in parallel relationship between the plurality of normally extending brackets and their associated retainers to comprise a subassembly which is then attached as a unit to an evaporator coil. Each of the coils is a continuous element that forms a complete loop with the ends then overlapping such that they are generally centrally located but are located on either side of midpoint such that their movement is not interfered with by other existing structures.

Abstract: Fresh air exchange is achieved by uncovering two ports which, respectively, allow stale air to leave the trailer through a high pressure duct and fresh outside air to enter the trailer through a low pressure duct. The trailer end of the ducts are connected to the refrigeration unit evaporator section where the evaporator fan provides the pressure differential. The opposite ends of the ducts are connected to a bracket mounted on the refrigeration unit frame and are exposed to the outside fresh air through a hole in the refrigeration unit's grille when the cover over the ducts has been opened by the linear solenoid under the control of the microprocessor.

Abstract: A refrigeration unit is provided with a manually operated fresh air vent made up of a cap assembly and a handle assembly which move together in a linear/axial direction. The handle assembly is rotatable to change the position of the fresh air vent. The fresh air vent controls both the providing of fresh air to the circulating air in the trailer and the exhausting of a portion of the circulating air. The evaporator fan is run continuously when the air vent is open to prevent the build up of gases produced by the perishable cargo.