Sorry the power supply didn't meet your expectations. An open load reading for a 6VAC (6 Volts Alternating Current) power supply typically reads very close to the supply's rated voltage, which in this case is 6 volts. When there is no load connected to the power supply, there is no current flowing through the circuit, so there are no voltage drops across any internal resistances or components. As a result, the voltage at the output of the power supply remains very close to its rated value, and you would typically measure close to 6VAC with an appropriate voltage measuring instrument.
However, keep in mind that there can be some minor variations and tolerances in power supply performance, and open load voltage readings can sometimes be slightly above or below the rated voltage, but they should generally be quite close to the specified value.
Where as a AC-DC & non-regulated power supply would usually read about 1.5x higher then the stated rating in a open load.