Okay, I changed the contactor and the noise is still there. I've looked at a few videos online and the closest thing Ive found that describes the noise is that it sounds like its constantly running in defrost mode...but with the fan on. Again, when the unit turns off, theres no noise at all. Does that make sense? Any other ideas? Thanks!
Wait.....didn't you say that you turned the outside unit off when you recorded the 2nd recording? Was that noise coming from the outside unit with the disconnect to it turned off and ONLY the inside unit running?
With the outside unit off the only thing that can be powered will be the circuit board and the contactor. They are the only things that are Low Voltage powered and that Low Voltage power comes from the Transformer inside the inside unit.
With the outside unit off the compressor won't be pushing refrigerant thru the lines so there shouldn't be much noise coming from that.
I agree with jbatey, call a professional to come out and look at it.
