Make sure nothing is loose or rubbing. Aside from that, the units do have a fair amount of fan noise. Small fans moving a lot of air create a lot of noise and with the roof being lower, you will hear it louder.
Amateur Radio Operator (KE5DFR)|Full-Time! - 2012 6.7L Ford Crew Cab Dually -2013 HitchHiker Champagne 38RLRSB - Travel with one Standard Schnauzer and one small Timneh African Gray Parrot