Carrier Heat Punp Compressor heat exchange unit outside Humming sometimes

[vdotmatrix]

I was out side and heard a loudish humming coming from the outside unit, with the fans NOT turning. I dont know what these means and i didnt notice it before. The fan starts to turn later up at some point with almost the same sound...I will try to capture this on video...

Any ideas.

[HayZee518]

The magnetic contactor for the blower and or compressor can be outdoors. The control circuit for the contactor is 24 volts. the movable part of the contactor is called the armature, the fixed part is the frame. They both are made up of steel or iron laminations. The laminations are supposed to be isolated from one another by a silicone grease or paper. When the contactor is closed you say it hums. This can be from two reasons. Maybe there is some dirt between the metal contact surfaces of the contactor or the copper shorting bars (wire) on the lower portion of the contactor are loose causing the hum.