The ornamental design for an air-conditioning outdoor unit, as shown and described.
1. Air-conditioning outdoor unit
1.1 : Front
1.2 : Back
1.3 : Left
1.4 : Right
1.5 : Top
1.6 : Bottom
1.7 : Perspective
1.1 is a front elevation view of an air-conditioning outdoor unit showing our new design; 1.2 is a back elevation view thereof; 1.3 is a left side elevation view thereof; 1.4 is a right side elevation view thereof; 1.5 is a top plan view thereof; 1.6 is a bottom plan view thereof; and 1.7 is a perspective view thereof.
The broken lines in FIGS. 1.1-1.7 depict portions of the air-conditioning outdoor unit that form no part of the claimed design.