Carl Greene, 53, said he needs time to sort out personal issues that he blamed on unspecified physical and mental stress. No return date was given.
Greene has not been seen in public since news reports broke last week about the foreclosure lawsuit. The bank's July 27 lawsuit said he owed $7,500 in missed payments dating to April 1. Greene took out a $400,000 mortgage on the $615,000 condominium in 2007.
According to Greene's statement, he has now paid the mortgage in full through October.
In 2009, the IRS filed a tax lien on the property. The lien was satisfied in late December, court records show.
"I sincerely apologize for being unavailable as I sort out my personal business," Greene said in a statement issued Wednesday by the agency. "My lack of attention to my personal financial dealings is a failure on my part."
Greene plans to take what he called a long-overdue vacation and vowed to come back "better and stronger."
PHA Board chairman John Street, the city's former mayor, said Monday afternoon that Greene had not returned repeated messages he had left over four days. Later that day, the office said Greene would be out through Tuesday.
On Wednesday came word of the weeks of leave.
Greene had been scheduled to take part in the city's mandatory foreclosure-prevention program on Sept. 16, court records show. It was not immediately clear whether he must still attend the court session.
Greene has led the Philadelphia Housing Authority, the nation's fourth-largest, since 1998. The agency has a $347 million annual budget and oversees 80,000 renters. He previously worked for housing authorities in Detroit, Atlanta and Washington, D.C.
Greene, who is unmarried and has no dependents, earned a base salary of $306,370 plus a $41,188 bonus last year.
Street, who now teaches at Temple University, did not return messages for comment on Wednesday.