WHERE in the world is Carl R. Greene?

That was the question all over town yesterday as Philadelphia Housing Authority board members, housing advocates and political insiders tried to figure out what was going on with the PHA executive director, whose posh condo is in mortgage foreclosure.

Former Mayor John Street, who serves as chairman of the PHA Board of Commissioners, said Greene had not returned his calls or e-mails.

"It's a little unusual that he would be unavailable under these circumstances," Street said, noting that he had spoken with other commissioners about the situation. "We want an explanation from the executive director. We want him to tell us what's going on."

PHA spokeswoman Nichole Tillman said Greene had notified staff that he would be out of the office yesterday and today. She said she had no further information on his whereabouts.

Street, meanwhile, said Greene owed the public some answers.

"He's a significant public official running a big public agency that spends a significant amount of taxpayer dollars," Street said. "He owes the public a level of transparency about all of this that we hope will be forthcoming."

This isn't the first time Greene has pulled a disappearing act. Back in 1999, then-Mayor Rendell announced he had hired Greene from Detroit. But the next day, Detroit's mayor said Greene had been persuaded to stay at his old job. During the confusion, Greene was unavailable while vacationing in Florida.

Yesterday, amid a growing firestorm over Greene's whereabouts and his financial troubles, housing advocates said Greene should be held to the same standards by which PHA residents must live.

"He collect rent from everybody else. If you don't have rent, he take you to court," said Diane Gass, president of the Norris Apartments Tenant Council. "He's not paying his own bills? That's unfair to everybody. I think that's a disgrace and embarrassing."

Greene, who makes $306,370 as PHA executive director, is facing foreclosure on his $615,035 Naval Square complex condo and recently settled a federal tax lien for $52,480.

In 2007, Greene bought the condo in the gated community in southwest Center City, taking out a $400,000 mortgage. Wells Fargo Bank sued Greene in July, saying he had defaulted on his payments and owed $386,685, which is the principal balance plus interest, late charges and other fees.

Virginia Wilkes, president of the Richard Allen Homes Resident Council, said her phone has been ringing nonstop since news broke about Greene's mortgage.

"He has those managers taking residents to court if they owe $25," Wilkes said. "How can you lead us to anything if you can't pay your own bills?"