An electronic control valve for an HVAC system of a vehicle may include, in the electronic control valve configured to control the angle of a swash plate (angle with respect to the surface perpendicular to a rotation shaft of a compressor) in the compressor in an HVAC system, a solenoid, a plunger coupled to the solenoid member and configured to slid according to whether the solenoid is magnetized, a valve body formed integrally with the plunger, and configured to open or close a supply flow path through which a fluid flows into the compressor, a discharge flow path through which a fluid is discharged from the compressor, and a control flow path through a fluid flows to control the angle of the swash plate mounted inside the compressor, a diaphragm configured to operate the plunger by the pressure of refrigerant, and a return spring configured to return the plunger, and the solenoid is applied with power according to a vehicle target cooling load.