Abstract: A vehicle climate control system develops a fog index based on relative humidity at or near the inner surface of the windshield, and uses the fog index to variably override the normal control settings. The relative humidity is combined with a pair of humidity thresholds to form a dimensionless fog index, and fog index values within a predetermined range are applied to a variable path function for transitioning between existing control settings and control settings that maximize defogging.

Abstract: An improved HVAC control method immediately closes an air inlet valve to provide full cabin air recirculation when an outside air quality sensor detects polluted air, and thereafter progressively re-opens the air inlet valve at a determined rate when the air quality sensor detects unpolluted air. Preferably, the air quality sensor quantifies the pollution level of the outside air, and the opening rate of the air inlet valve is determined based on the detected pollution level. Following a high level of detected air pollution, the valve is re-opened at a relatively slow rate, and following a low level of detected air pollution, the valve is re-opened at a relatively fast rate.

Abstract: A pneumatically-operated control valve selectively opens and closes a passage between discharge and crankcase chambers of a variable capacity refrigerant compressor for purposes of controlling the compressor capacity, and includes an integral pressure sensor for measuring the compressor discharge pressure. The valve includes a plunger having an axis, a stopper biased against a seat in the passage coupling the discharge and crankcase chambers, an annular bellows and a pressure sensor. A portion of the plunger passes through the annular bellows, and one end of the bellows is attached to the plunger for axially displacing the plunger to unseat the stopper. The stopper and plunger are maintained in engagement, and have axial bores that are aligned to form a passage between the compressor discharge chamber and a cavity in which the pressure sensor is retained.

Abstract: An integrated capacity control valve for a variable capacity refrigerant compressor includes an integral pressure sensor that is continuously coupled to a discharge port of the valve for measuring the refrigerant discharge pressure. A plunger of the control valve is disposed within a passage coupling the compressor crankcase to the discharge port, and is positioned by pneumatic and electric control elements to regulate the refrigerant suction pressure. The plunger has intersecting axial and lateral bores that define a continuous passage between the discharge port and a cavity in which the pressure sensor is retained so that the sensor is continuously exposed to the discharge pressure regardless of the plunger position, and refrigerant discharge pressure in the lateral bore produces a bias force on the plunger that compensates the pneumatic suction pressure setpoint for a pressure drop between the evaporator and the suction port of the valve.