text: is it bad to run a window a/c uit rated at 125v at 120v?  i want to use the unit with a gas powered generator.   won't be a problem. just don't exceed the amperage and keep the a/c on it's own fusible circuit. most 120/125 volt systems max out at 20 amps. air conditioners are usually 15 to 20, a colour tv is 8 or so, hair dryers 9-12, clothes dryers...forget it.  and check the amps output on your generator.  or stay naked all of the time. sleep in the shower.