Scroll Technology: 
The Smoothest, Quietest, Most Efficient Compressor Technology Ever Invented.

The heart of an air conditioner is its compressor. And no other manufacturer today offers the benefits of scroll technology throughout its entire residential air conditioner product line. It's a technological advancement that acheives higher efficiency and durability at the same time. compressor
scroll cycle Scroll Compresssors use advanced engineering and flow dynamics to more efficiently and smoothly compress gas refrigerant. Old-fashioned reciprocating compressors use pistons and valves to compress and move gas. But with a scroll compressor, these noisy high-wear moving parts are eliminated.
With a Scroll compressor, your air conditioner will provide years of reliable operation. It's one more commitment that Ruud makes to using only the latest and most efficient technology.

A heat pump central will always save you money because, anytime above 32 F
your central can bring heat from the outside during winter, which effectively lowers
your energy consumption.  Also air from the heat pump will not be oxidized by heating elements (which turn on when pump is not meeting need in very cold weather) therefore it will be better for your health.

On a separate note, try to buy a fridge with the coils in the back. It is not too hard to pull a fridge out and clean the rear coils. (The fridges with the coils in the bottom claim they are easy to keep clean but that is not true. Also the coils on the bottom require an additional fan which also uses more energy.) The rear coils should be at least three inches from the rear wall for good ventilation of heat; Six inches of clearance on top of the fridge ; and two inches on at least one side of the fridge.