By Mark Hosenball and Dhanya Skariachan WASHINGTON/NEW YORK (Reuters) – The U.S. Secret Service visited the office of a Pennsylvania-based refrigeration contractor, Fazio Mechanical Services, in connection with an investigation of the Target Corp consumer data breach, a spokesman for the agency said on Wednesday. Fazio is the largest refrigeration contractor in the Western Pennsylvania region, and Target is one of its clients, according to the Sharpsburg-based company’s website. A law enforcement source told Reuters that evidence suggests the hackers stole login credentials from Fazio and may have used the credentials to break into Target’s network.