Abstract: An electronic controller receives an evaporator inlet (or outlet) temperature sensor signal and measures the time required for the evaporator to be heated from compressor clutch cut-out to compressor clutch "ON". Depending upon the elapsed time, the controller selects from a predetermined schedule, a new value CLHOFF of the evaporator inlet temperature at which the compressor is next cut-out, raising CLHOFF for lighter thermal loading to prevent evaporator icing and freeze-up and lowering CLHOFF for heavy thermal loading to prevent unwanted compressor cycling.

Abstract: An automotive air conditioning system utilizing an electrically operated refrigerant expansion valve controlled by a micro-computer. The compressor clutch cut-off is controlled by a suction pressure sensor at high thermal load. At partial flow conditions of the expansion valve, representative of moderate evaporator thermal loading, the micro-computer controls compressor clutch "ON" time from an accumulated count incremented by a predetermined amount according to suction pressure change. When the accumulated count over successive signal sampling intervals reaches a predetermined maximum the clutch is cut-out based on the count which is representative of a predetermined time interval.

Abstract: A method of controlling a refrigeration system employing an electronic controller for operating an electrically actuated refrigerant expansion valve supplying the evaporator or endothermic heat exchanger. The controller is of the type which modulates the valve for refrigerant flow to maintain a desired target level of superheated vapor discharging from the evaporator. When the compressor return, or evaporator discharge pressure (P.sub.c) is within a preselected range the system employs a strategy to increment or decrement the target level of superheat depending upon whether the rate of change (.DELTA.P.sub.c) of discharge pressure is positive or negative and thereby maximize pulldown by minimizing compressor cycling to achieve the superheat target.

Abstract: An electronic controller receives a suction pressure sensor signal and measures the time required for the evaporator to be heated from compressor clutch cut-out to compressor clutch "ON". Depending upon the elapsed time, the controller selects from a predetermined schedule, a new value CLHOFF of the suction pressure P.sub.s at which the compressor is next cut-out, raising CLHOFF for lighter thermal loading to prevent evaporator icing and freeze-up and lowering CLHOFF for heavy thermal loading to prevent unwanted compressor cycling.

Abstract: A system for controlling refrigerant flow in an air conditioning system employing an electrically operated valve for controlling flow of refrigerant from the condenser to the evaporator. Separate thermistors sense the temperature of the refrigerant entering and discharging from the evaporator. A comparison of the sensed temperatures is used to modify the control signal to the valve for maintaining proper refrigerant flow to the evaporator. A control module is directly attached on the valve body to enhance heat conduction.

Abstract: A system for controlling refrigerant flow in an air conditioning system employing an electrically operated valve for controlling flow of refrigerant from the condenser to the evaporator. Separate thermistors sense the temperature of the refrigerant entering and discharging from the evaporator. A comparison of the sensed temperatures is used to modify the control signal to the valve for maintaining proper refrigerant flow to the evaporator.