A review by Bush administration officials that could lead them to relax a new efficiency standard for central air-conditioners has been dealt a blow by an unlikely source: the nation's second-largest air-conditioner manufacturer. The company, Goodman Manufacturing, which owns Amana and several less prominent brands, has sent a letter to Energy Secretary Spencer Abraham asking his department not to revise the standard, which was approved in the last days of the Clinton administration and would require new models to be 30 percent more efficient than the current minimum standard.