The ornamental design for a portion of a ceilingfan housing, as shown and described.
FIG. 1 is top perspective view of a portion of a ceiling fan housing showing my new design;
FIG. 2 is a bottom perspective view thereof;
FIG. 3 is a front elevation view thereof; and,
FIG. 4 is a bottom plan view thereof.
The broken line showing of the ceiling fan housing is included for the purpose of illustrating environmental structure and forms no part of the claimed design.