The last couple of days I have noticed vibrations from the A/C. Vibrations occur with the fan only or the compressor running. Can feel it in the walls and in the rear bathroom. I have removed the bottom of the A/C inside and removed some mud dubbers nest on the squirrel cage and on other places. Went up top and remove the shroud and found a few there . The fan turns freely as well as the squirrel cage. No grinding or particular sound. Cools very well. I did tighten the four bolts on each conner of the A/C one was a little loose. Not sure that did much...any ideas?