Abstract: A method of operating a directed relief valve to ventilate a refrigerant by sensing the concentration of refrigerant leakage from the air conditioning system, and if the first concentration exceeds a threshold, by sensing a second concentration. If the first and second concentrations exceed a predetermined concentration, the system will send a leak message to the operator and/or ventilate the refrigerant to the surrounding atmosphere. The system continuously monitors the refrigerant leakage concentration when the vehicle engine is operative, but only periodically monitors the refrigerant leakage concentration when the vehicle engine is inoperative.

Abstract: A blowoff valve assembly includes a diaphragm separating a refrigerant connection from an ambient port open to the atmosphere. The refrigerant connection is preferably connected to air conditioning system such that the diaphragm is in contact with refrigerant from the system. The diaphragm is deflectable based on the pressure of the refrigerant and is operatively connected to a switch. When pressure of the refrigerant drops to a predetermined level, the diaphragm deflects to activate the switch. Additionally, the assembly also includes a detonable squib that explodes and ruptures the diaphragm, allowing the refrigerant to flow from the refrigerant connection to the atmosphere. Additional features, such as sensors for detecting refrigerant outside of the system, a collision subsystem, and an associated controller are also disclosed.

Abstract: An air conditioning system using a refrigerant to control a temperature of a climate-controlled area. The air conditioning system comprises a refrigerant circuit and a compressor coupled to the refrigerant circuit. The compressor includes a compression mechanism comprising a swash plate and at least one piston engaging the swash plate for compressing the refrigerant. An electric motor has a drive shaft that supports the swash plate at an inclination angle. The swash plate is adjustable between a plurality of inclination angles or stroke positions to adjust a current pressure in a low-side pressure portion of the refrigerant circuit. An electronic control valve adjusts the compression mechanism between the plurality of stroke positions to adjust the current pressure. A controller is programmed to control the electronic control valve until the current pressure is within a predetermined limit of a target pressure.

Abstract: A HVAC system is operable in a fresh air mode and a recirculation mode for use in a vehicle is disclosed. The HVAC system includes a blower and a HVAC module in fluid communication with and downstream of the blower for warming and cooling the air to be circulated through the passenger compartment in both the fresh air mode and the recirculation mode. The HVAC module includes an inlet duct in fluid communication with and upstream of the blower and located above the dashboard for drawing air from the passenger compartment above the dashboard and through the blower and the HVAC module in the recirculation mode. The inlet duct above the dashboard improves air circulation within the passenger compartment that improves the air warm-up rate. The inlet duct above the dashboard also improves the airflow across a windshield to prevent fogging of the windshield.

Abstract: An improved method and apparatus for diagnosing the condition of an automotive HVAC refrigerant compressor based on information contained within the signal produced by a high-side pressure sensor provided for system control purposes. The output signal of the pressure sensor is divided into its DC and AC components, with the DC component being used for system control purposes, and the AC component being used for diagnosing the condition of the compressor. Pulsations of the AC component (which conventionally are removed by filtering for control purposes) correspond to individual piston stroke cycles. The pulsations indicate compressor operation and are counted for purposes of determining the actual compressor speed. Since existing pressure sensor information is utilized to verify compressor operation and to determine compressor speed, the system cost impact due to the diagnostic evaluation is minimal.

Abstract: A valve assembly for controlling the flow of refrigerant and coolant through an HVAC system is provided. The valve assembly includes a refrigerant housing defining a refrigerant conduit with a refrigerant inlet and a refrigerant outlet. A refrigerant valve is disposed within the refrigerant conduit for controlling the flow of refrigerant between the refrigerant inlet and the refrigerant outlet. The assembly also includes a coolant housing defining a coolant conduit with a coolant inlet and a coolant outlet. A coolant valve is disposed within the coolant conduit for controlling the flow of coolant between the coolant inlet and the coolant outlet. An actuator assembly is coupled to the refrigerant and the coolant valves for simultaneously actuating the valves.

Abstract: An automotive air conditioning system orifice tube type refrigerant expansion valve is axially symmetrical, so as to be error proof at installation, and/or so as to operate in a bi directional refrigerant flow. A pair of coaxial screens surrounding each end of the orifice tube, an inner noise attenuation screen of finer mesh, and an outer particulate screen of coarser mesh, provide upstream particulate exclusion and downstream noise attenuation without the potential for reverse installation. In addition, by pass ports allow for a by pass flow should the downstream inner screen become plugged.