KARJ's transmitter and antenna are located at 33°6′39″N 117°9′13″W / 33.11083°N 117.15361°W / 33.11083; -117.15361 in Escondido, California near Frank's Peak on Mount Whitney.

The callsign was changed KFSD while owned by the Astor Broadcast Group, who chose a format of classical music acquired from Lotus Communications in 1997.

Station management admitted that the classical format has been in the red for years and the change was made to increase revenue.

On September 26, 2017, Entercom announced a divestment of three stations (KSOQ, WGGI, and KSWD) to the Educational Media Foundation as part of its merger with CBS Radio (which locally owned KEGY and KYXY) to comply with FCC ownership rules in the San Diego market; the FCC approved the sale of all three stations on November 2.

Upon the closing of the acquisition on November 16, EMF flipped the station to its Christian contemporary hit radio network Air1 at 1:00 p.m. that day.