What is the mailing address for first source credit union? Mailing Address: First Source Federal Credit Union. 4451 Commercial Drive. New Hartford, NY 13413. Phone: (315) 735-8571. 1-800-735-8571. 24-Hour Account Access:Why choose one source fcu? Since 1937, One Source Federal Credit Union has grown from 10 telephone company employees to over 12,000 members. And since that time, we remained focused on the credit union philosophy of "People Helping People." With locations in El Paso, Texas and Las Cruces, New Mexico, One Source FCU is here to help you with all your Life's Choices.What is first source bank? Founded in 1938, First Source is a not-for-profit, Member-owned financial cooperative with branches in New Hartford, North Utica, South Utica, Rome, and Herkimer. They serve more than 50,000 Members throughout Oneida and Herkimer Counties in Central New York, offering a full suite of deposit and loan products for both personal and business banking.What is it like to work at first source? “I have been an employee of First Source for 11 years now. The credit union genuinely cares about the needs of their members. At First Source you are part of team where everyone shares common goals, and the environment is focused on collaboration.