A federal employe union urged 56 Housing and Urban Development employes yesterday to return to work Monday following a D.C. court ruling that temporarily blocks HUD Secretary Samuel R. Pierce from dismissing or downgrading about 200 department workers.

Ernest Parker, president of the American Federation of Government Employees Local 476, said few of the workers were aware of the ruling. "Most of them don't know they've still got jobs," he said. "We're trying to locate them and notify them."

Parker said the court order expires on Nov. 10, at which time the union will seek a permanent reversal of HUD's personnel reduction plans.

Union spokesman Gregg Holman said that 144 employes had been scheduled for downgrading before the restraining order was issued on Friday.

Parker and Holman went around with copies of the temporary order to several farewell parties Friday night. "You should have seen their faces," Holman said. "The parties turned from wakes to New Year's Eve."

District Judge June L. Green issued the order Friday after Rep. Martin O. Sabo (D-Minn.) filed suit against Pierce. Sabo argued that congressional approval is necessary before any reorganization of the department, including a reduction in work force.