Received a request from a cell phone shop in Modesto, California, for their air conditioning not responding. Tech arrived onsite and inspected the equipment. Reset the thermostat to cooler temperature for the back room, per manager request. Thermostat was not responding, traced issue to a tripped smoke detector for the backroom unit. Spoke to the manager, some food had been burned recently in the room. Reset detector and cycled units. Detector didn't trip again, all other equipment working well.