Tenants in a Pinnacle Group building on Riverside Drive and 144th Street are suing their landlord, claiming that the six-story rental building is in need of extensive repairs.

The building, at 668 Riverside Dr., is set to undergo a conversion into condominiums, but the tenants are claiming that “mold, constantly leaking pipes, rotting wood, fallen ceilings, and dangerous electrical environments” must be fixed before the conversion can begin.

The Pinnacle Group is a large landlord, with an estimated $1 billion in real estate in Upper Manhattan and parts of the Bronx. Its holdings include more than 21,000 rent-regulated apartments in roughly 420 buildings citywide.

This is not Pinnacle’s first tussle with tenants: In 2006, tenants’ groups and politicians alleged that the company improperly attempted to remove rent-stabilized tenants and raised rents on the strength of false major capital improvements, prompting a state investigation of allegations of tenant harassment. That investigation ended with a negotiated settlement in which Pinnacle admitted to no wrongdoing, but it did hire an auditor to analyze its rents and ended up adjusting some.

In the latest suit, filed in June in New York City civil court, tenants requested Pinnacle and its owner, Joel Weiner, fix the problems. An additional proceeding was filed last month, with tenants suing the landlord and the city’s Department of Housing Preservation and Development, alleging that conditions in the building violate the city’s Housing Maintenance and Building codes.

“Even to make it habitable, the building needs millions of dollars of work,” the attorney representing the tenants, Adam Leitman Bailey, said. “If he put these apartments on the market as is, he’d be defrauding possible buyers.”

The attorney representing Pinnacle, Kenneth Fisher, said the company has improved the buildings it has bought, fixing thousands of pre-existing violations. The company “has been unfairly painted as the poster child for gentrification,” Mr. Fisher, a partner at the law firm WolfBlock, said. “They’ve turned substandard housing into good housing stock.”

A report by Rand Engineering & Architecture, paid for by the tenant group, indicates the building would need some $1.87 million in repairs to comply with the plans the developer has filed with the attorney general for the conversion to condominiums. This includes $336,000 for a new roof.

There is one other case pending against Pinnacle: In 2007, residents filed a suit in the U.S. District Court alleging deceptive practices, harassment, and racketeering under the Racketeer Influenced and Corrupt Organizations Act. The Pinnacle Group moved to dismiss the case, and filed a lawsuit in June against Manhattan’s president, Scott Stringer, to force his office to release records of his communications with tenants who filed the RICO suit.