I have a month old Harman Accentra FS with OAK. Hubby cleaned it yesterday & we noticed overnight that there was an annoying whirling / whistling noise coming from the stove. I pinpointed that it is when the room temp is on High. Turn it to low & it goes away. And it sounds like it's coming from the side that the control box is on. Any suggestions on what to do or check. Thanks.