We have a 4 ton York heat pump outside our bedroom. Since it has started warming up, the AC has been running and there is some noise coming into the house. The noise is sort of a humming, but the pitch oscillates back and forth every second or two, and then sometimes stays constant for a little bit, then starts oscillating again, sort of like the vibration is coming into phase and then drifting out of phase.
I don't hear the noise when it's just the air handler running. The AC has always made noise but I don't remember it being like this last year, although it's hard to say. Can you give me any ideas what might be causing this?
I am a light sleeper and normally I like the constant drone of an AC to help me stay asleep. However this variable noise is making it hard for me to fall asleep. My wife doesn't hear it but I do.
I am not looking for DIY info, just some ideas so I can tell the tech what to look for. Odds are the tech might not hear the noise like I do, it is subtle but annoying.