Nick you know they will acclimate to the weather in your area like it or not , its just taking them LONGER since summers are not hot in Iceland even though they have a lot more hours of sun than you or I , they will get used to the heat and slowly use less and less AC, its same way around years ago when one of my neighbors moved back to MN from Fremont CA, she froze most of the winter her first winter then she got more used to it and her second winter was much easier for her. If this is a window unit then ask the LL if there is some thick round foam gasket can be put between the unit and all the wood surfaces so say as the compressor fires up or fan speed changes it shouldn't vibrate as much .