[A/S] electrical question

["michelle" <safoocat@xxxxxxx>]

1.    1971 A/S we just hooked up the exterbal electical power and discovered
the charger converter
is dead so I took it out and bench tested it to be sure. My thoughts are
couldn't I substitute
the old converter charger with a newer technology battery charger of similar
ratings?

2.    When connected to 110V external power there is a hum comming from the
roof air conditioner.
What is that and is there any way to silence it? The air conditioner comes
on when the thermostate
is raised.
thanks,
Michelle