Three applicants filed in 1976 for one of the last Class C FM allotments in Phoenix: American International Development, owned by Julia Zozaya; Herbert Owens, owner of Turf Paradise; and KXIV. In June 1979, the Federal Communications Commission issued an initial decision awarding the frequency to Zozaya. However, KXIV challenged the initial decision, alleging that the signatures on Zozaya's applications did not match; the commission's review board agreed, overturning the initial decision and finding in favor of KXIV. Zozaya, who was legally blind, appealed the review board's finding, claiming that her disability resulted in the mismatched signatures, and on May 7, 1981, the FCC issued a final ruling awarding the 99.9 frequency to Zozaya. The station signed on the air July 4, 1982, as Spanish-language station KNNN, Phoenix's first Spanish-language station on FM and at the time the only one operating in Arizona. It operated from a converted home at 4548 W. Osborn Road on Phoenix's west side. Technical difficulties that developed on the first day of operation prompted KNNN to go silent again until July 12. In late 1983, Zozaya sold the station for nearly $4 million to TransCom Communications, owned by Robert G. Herpe and former KDKB owner Eric Hauenstein. By January 1984, it was apparent that a format change was likely coming as the new owners engaged former KDKB morning man Bill Andres. KNNN ceased broadcasting on February 28 to make way for TransCom's adult contemporary outlet, KLZI, The new outlet, doing battle with KKLT, made a dent in its competitor's ratings in the first survey. which began broadcasting March Meanwhile, the Phoenix market would not get another Spanish-language station on FM until the creation of KVVA-FM in 1987. KLZI—along with KSUN, which TransCom was in the process of buying—was sold in 1986 to Duffy Broadcasting of Dallas in a $15 million transaction. It was announced the same day as the sale of KOOL-AM-FM for the same price, with both tying as records for the Phoenix market.
Relaunch as KESZ
On January 15, 1988, KLZI gave way to KESZ "EZ-Rock 99.9", remaining in the adult contemporary format. Also introduced was a new airstaff, which included Barry Chase and Beth McDonald in mornings, as well as Marty Manning. Success was not immediate: with the station languishing at 15th in the ratings that summer, Chase was fired and Manning moved to mornings opposite McDonald. After the Arizona Television Company, owner of KTVK, acquired the station in 1990, KPNX meteorologist Bill Austin joined the morning show, which became known as "Beth and Bill". In the span of a year, Arizona Television purchased KESZ, Phoenix Magazine, and a TV production studio. The station's share remained steady, but cume increased throughout the 1990s to a top-5 position. 1996 also saw the first time KESZ played Christmas music over the holiday season. In 1997, Arizona Television—by then known as MAC America Communications—announced that it was forming a joint venture with Buck Owens, owner of KNIX; the venture, known as OwensMAC, would operate KESZ and MAC America's struggling station at 103.5 FM. In 1999, KESZ became the market's top-billing station for the first time.
KESZ under Clear Channel/iHeartMedia
In 1999, Jacor, which was already in the process of merging with Clear Channel Communications, acquired KNIX from Owens and KESZ from OwensMAC for $84 million and $58 million, respectively, marking the end of one of the market's last large independent owners. "Beth and Bill" continued in morning drive until Austin retired in February 2010 as a result of bladder cancer, when the show was renamed "Beth and Friends"; he died four months later at the age of 55. KESZ has continued to see success with Christmas music and is typically one of the top-rated stations in the United States during the holiday season. In the Holiday 2019 Nielsen Audio survey, KESZ earned a station-record 19.2 rating, up from the prior two years.
KESZ's HD Radio signal is multiplexed. The main signal is a simulcast of KESZ's adult contemporary programming. The second channel initially carried KEZ's Classic Channel programmed by iHeartMedia's Format Labclassic hits format consisting of songs from the 1960s, 1970s and 1980s. As of April 2017, this changed to iHeart 70s. On October 1, 2017, KESZ-HD2 switched to a Christmas music format and continued to do so until November 14, 2018, when the primary station went Christmas for the holiday season, and the HD2 moved to soft adult contemporary as "99.9 HD2 The Breeze." The move gave iHeart the right to use the "Breeze" name in the state of Arizona, preventing any other station group to use the name in the case of another station flipping to soft AC, which saw a renewed interest in late 2018. In September 2019, KESZ added a simulcast of KGME “Fox Sports 910” to its HD2 stream, bumping The Breeze format to HD3.
