I have a heat pump. It's not cooling the house like it should. I went outside to cool down after looking at the thermostat and it was set to 70 and it was 78 in the house. The fan comes on like normal, but like I said, it's not cooling. The filter inside the house is brand new and everything was working fine up until a couple days ago. Since then, about every 3 to 3.5 minutes or so a tone will come from somewhere in the unit. It lasts a few seconds then stops. I recorded it with my phone and compared the tone to a tone generator and it's almost exactly 480Hz. Not a beep. Not a buzz. Not a click. Not a tick. Not a rattle. An almost B flat musical tone. I've never heard anything like this before and have no idea what it could be. BTW, the click and smoke you hear and see in the video is me lighting a cigarette. Tone happens at the end-ish of the video.
**UPDATE**
So I've not run the system for fear of damaging things, but when trying to show my girlfriend the sound it was making I turned it on and after a few seconds the unit turned off and won't turn back on. I thought that the startup switch was the culprit all along, but It'll turn on when in Heat mode, just not in cool mode. I'm really at my wit's end here. If someone could give me an idea of what this could be, it would help out a great deal. We are on a very limited income and can't really afford to spend thousands of dollars if it's something simple.