My living room one 15,000 Dometic and I found the plastic blower wheel was worpped and causing a lot of vibration. New blower wheel was $8.97 and shipping was $8.98 LOL now my unit is very quiet. Also you might check to see if mud dobbers made a mud ball nest on the outside blade causing you vibration.
2014 Palomino Columbus 3650TH
435AH 12V VMax Charge Tanks, 520 watt Monocrystilline Solar Array, Morningstar MPPT TS-60 CC,Morningstar Remote,Cotek True Sine Wave Inverter,Cotek Remote Controller,50amp Progressive Hardwire Surge Protector
2015 Dodge 3500 6.7L 4X4
2011 CanAm Commander XT 1000