Weird AC noise?

[Orleans]

Maybe this is a weird question, and I'm not even sure how to describe it, but does anyone else have an issue when using AC or heat in the winter where there's a climbing hum, like, there's a whirring sound and then the pitch continues to climb to a point and then start over?

 

[kiev]

Does it sound like it is the blower fan, or the motor in the AC compressor?

 

[Orleans]

I'm not sure of the difference. If you put it on max, the fan is cranked, but until then, it's pretty weak. Feels like under the feet. But the heat/AC still works, it's just that weird climbing hum climbing pitch in steps.