Tuesday August 13 at around 1430 hours we was dispatched to a possible electrical fire at McDonald’s. Once on scene smoke was found in the lobby area and was pointed toward the roof area were a fire was possibly at. Repair people was already on the scene fixing one hvac unit when this one failed. Fire resistant insulation in the duct work was scorched and smoldering and then blown through the duct work. We worked to ventilate the structure and determined no extension of fire or issues other than the coil system in the hvac unit failed. We want to thank Tazewell pd for assistance in the evacuation of the building and blocking the parking area for us to work safely.