Abstract: An air cycle automotive air conditioning system for providing conditioned air to an automotive passenger compartment (20) includes an air compressor (10) tandemed to an expander (12). The expander (12) is efficiently run so as to expand air to a very low temperature, sending recovered work back to the compressor (10). The very cold expander air is then mixed with warmer air from other sources, providing a proper volume flow and temperature of air to the passenger compartment (24).

Abstract: An improved system and method for suppressing high side pressure transients in a motor vehicle air conditioning system due to engine speed transients during vehicle acceleration through the use of a throttling valve. The throttling valve may be mechanically or electrically activated, and is connected in the low pressure side of the air conditioning system to controllably restrict refrigerant flow in response to one or more parameters that detect or anticipate a high side transient pressure condition. The parameters may include the high side pressure itself, or engine parameters such as engine speed and vehicle speed. In a preferred embodiment, the throttling valve may be controlled to prevent evaporator icing in addition to suppressing high side pressure transients.