Persistence paid off Friday night for Montecito firefighters who were called out twice to a reported smoke odor at the Bonnymede condominium complex.

The first call to the Montecito Fire Protection District came in at about 9:30 p.m., reporting a smoke odor in a two-story residence in the 1300 block of Plaza De Sonodares, district spokeswoman Geri Ventura said.

“One engine responded, and although there was no smoke or smoke odor present when they arrived, circuit breakers and radiant heating systems in the residence were checked,” she said.

Usuing thermal-imaging and gas-analysis equipment, firefighters were unable to find any abnormalities, Ventura said, and left the scene after advising the resident to get a working smoke detector.

At midnight, the same resident called back to report a continuing odor of smoke, and this time firefighters found a haze of smoke in the residence.

The building was evacuated, and firefighters eventually traced the problem to an adjacent vacant unit, Ventura said.

“Crews made entry into the structure, and found the fire origin to be located within the walls inside the structure,” said Ventura, adding that the cause remained under investigation.

“The smoke source came from an unoccupied unit under construction, with no working smoke detector,” Battalion Chief Todd Edwards said. “We are lucky the neighbor was diligent about reporting the situation.”

Fire officials encouraged all residents to check their smoke detectors and make sure they are in working order.

— Noozhawk executive editor Tom Bolton can be reached at tbolton@noozhawk.com. Follow Noozhawk on Twitter: @noozhawk, @NoozhawkNews and @NoozhawkBiz. Connect with Noozhawk on Facebook.