I have an 2005 suburban, about three years ago it started this tea kettle whistle on the front passenger side when it was cold out, pitch and intensity of the whistle changes when you press on the gas and depends how hard your on the gas.The first winter with this noise it would whistle and stop once the truck warmed up (thought no big deal it’s an older truck). The second winter with this noise it would whistle then there would be this pop noise (it would cause everyone in that vehicle to jump cause it was loud), but it would quit and be quiet the rest of the drive. Then now into the third winter with this noise and it is still there and now it is constant it does not stop when truck is warm, it still occasionally will pop but then returns to whistling. We thought it was speakers so we replaced those, I’ve turned the heat off and it is still there so I don’t think it’s blower motor. It sounds like it is in the location by the tweeter or the vent right on top by dash and windshield. Any ideas?