It may be the end of April, but there was no spring thaw at Thursday's board meeting of the Port Authority of New York and New Jersey. Port Authority commissioners had been expected to vote on a $3.9 billion capital and operating budget, which would have signaled some movement on an impasse that has held up major projects for the agency. However, Chairman Lewis M. Eisenberg said the budget had been discussed among board members, but a decision was made not to take a vote. No reason was given for the inaction. Board members have been paralyzed on the major items pending resolution of a 16-month dispute between New York Gov. George Pataki and New Jersey Gov. Christie Whitman over Port Authority revenues.