The refrigerator recently started making a weird whirr whirr whirring sound….all the time. It is louder when I put my head into the refrigerator upper section. I cleaned the dust off out of the area that I opened up in the back of the refrigerator…I think this is coming from inside the refrigerator side of the box…any ideas what causes something like that? Would love to replace a part to stop the mildly loud but very annoying noise.