0557 hours. Centereach Fire Department responds Millers Ale House at 4000 Middle Country Road in regards to an automatic alarm. Units arrive to find the fire alarm system active and smoke in the building. Crews quickly identified the problem within an HVAC unit on the roof. Power and gas to the unit was shut off and the building was ventilated to clear the smoke. The Lake Grove Fire Marshal performed a full inspection of the restaurant and gave them a clean bill of health. The restaurant opened at their normal time.