A method for cooling air in an HVAC system includes moving refrigerant through a closed refrigeration circuit having, inter alia, an expansion device subsystem, which includes a full-load pathway and at least one partial-load pathway and a flow selector for directing refrigerant flow from the condenser to either the partial-load pathway or the full-load pathway. The method also involves directing refrigerant flow from the condenser to the full-load pathway when the refrigerant pressure is greater than or equal to a first preselected activation pressure and stepping down a refrigerant pressure with a set orifice and directing refrigerant flow from the condenser to the partial-load pathway when the refrigerant pressure is less than a second preselected activation pressure and stepping down a refrigerant pressure with a variable expansion device configured for partial loads. Refrigerant is delivered from the full-load pathway or partial-load pathway to the evaporator.