Patent ID: 8047449

Claim:
An expansion valve for an air conditioning system circulating refrigerant through a compressor, a condenser, and an evaporator, comprising: an inlet for receiving refrigerant liquefied in the condenser; an outlet for supplying refrigerant to the evaporator; a valve element for controlling flow of refrigerant between the inlet and the outlet, wherein the valve element is normally closed; a control assembly coupled to the valve element and responsive to at least one temperature or pressure in the air conditioning system to open the valve element to variably meter the refrigerant to the evaporator; and a bleed passage between the inlet and the outlet, bypassing the valve element; and a check valve in series with the bleed passage for substantially blocking refrigerant flow in the direction from the outlet to the inlet, wherein the check valve is biased for blocking refrigerant flow in the direction from the inlet to the outlet unless the pressure of refrigerant in the inlet is greater than the pressure of refrigerant in the outlet by a predetermined threshold.