Outside Unit Humms

by Scott
(Pittsburgh)

I have a Carrier outside unit. It was working fine all summer till the other day i noticed that the house was getting much hotter.

I turned the ac off and back on again, and the thermostat clicks once for the call for cold air and then 5 secs later, clicks again, like off?

I reset all the breakers inside and out, and the outside unit will not kick on? It just humms, starts with a constant electrical hum, and then every 30seconds or so its a much louder electrical hum, like its trying to start, and then nothing?

any thoughts?