Kennett Fire Company was dispatched to South Union Street for a fire alarm. Upon arrival, Officers made entry with the store owner to find a smoke condition inside. The assignment was quickly upgraded to include Avondale, Longwood, and Po-Mar-Lin fire companies. Engine crews entered the store and connected stores to search for the cause of the smoke. No visible fire was present. Thermal Imaging Cameras were utilized to search the walls, ceiling, and electrical. Ladder crews took to the roof to examine air conditioning units and vents. Finally it was found that one of the refrigeration units was no longer running and should be. After further examination, it was highly probable that the electrical components on one of the units were no longer function as a result of overheating. The fire is still under investigation by Fire Marshals.