Try mapquest "UPS O'Hare Hub" on 610 S. Access Rd Chicago, IL 60666 and some suggest "610 South Access Road, Franklin Park IL 60131" as destination
Some folks in past took Uber from terminal 1 and about $20 (in 2016)
Its on the south side of the airport in the cargo area.
Let the security folks guide you into ops. Be careful, lots of vehicle traffic as you walk across the property