Probably the contactor. When the furnace indoors is calling for
cooling, it sends a 24 volt signal to the outdoor unit.

To silence this, change your thermostat from "cool" to "off".

--

Christopher A. Young
You can't shout down a troll.
You have to starve them.
..

wrote in message
oups.com...
Hi,

I went out into the yard this evening and heard my air conditioner
humming. The unit hasnt worked properly since we had a major power
outage and so the only way to turn it on or off is at the breaker. I
removed the wires going into the breaker but the unit is still
humming.
I openned the unit and the only power wires I can see are the
black/white/ground. It is a very old sears model and I cant find any
other shut off switch. What's going on!! Should I be concerned about
the humming and if so, how can I completely remove the power to the
unit without getting an electrician involved. I even tried going
breaker by breaker to see if there was a wire touching but nothing
stopped the humming

Thanks