I have a 2014 HL North Trail, purchased used. The AC and the fan made loud bearing noise. After pulling the roof top covers off there were no "cups" for oiling the bearings. I put a few drops of oil on the bearings I could get too. I turned the fan on and off and oiled again. That seems to do the trick. It did not help to pull the interior metal plates off the roof top unit. I will carry oil with me from now on.