The refrigeration mechanic, who appeared to be in his 50s, had apparently fallen about 20 feet down the air duct from the roof around 11:15 a.m. while making repairs at the building at 2310 N. First St.
He yelled for help and someone on the second floor of the building heard him and called 911, Stallard said.
Firefighters rescued the man by cutting through the duct from the first floor ceiling and pulling him out, Stallard said. He was rescued around 1:10 p.m. and was transported to Valley Medical Center.
The repairman injured his back and suffered a 3-inch cut to his right forearm. He was slipping in and out of consciousness during rescue efforts, but was expected to survive, Stallard said.