All but three of the 35 room air conditioners Consumer Reports recently rated scored “excellent” in tests focusing mainly on temperature and humidity control. And even those three, which scored “very good” in that crucial measure, should keep you cool this summer.

The top-scoring models overall, however, were the ones that also performed the most efficiently and quietly.

All the models we tested meet the energy-efficiency rating (EER) of 9.7 required for units with a cooling capacity below 8,000 British thermal units per hour, and the 9.8 EER for those 8,000 to 13,999 Btu/hr.

Moreover, most small and midsized machines we tested meet or exceed the 10.7 EER needed for federal Energy Star designation. (Energy Star is a voluntary federal program that helps identify models at least 10 percent more efficient than the standard.)

One large unit, the 10,400-Btu/hr. Friedrich SS10L10-A, hit the 12.0 mark, the highest we’ve seen a manufacturer post. Top-rated in its category, the $800 Friedrich was also the most expensive. By far.

That’s sharp contrast to the prices for many of this crop of air conditioners, which dropped from comparable units we tested last year. Still, lower prices don’t translate to fewer features. New models in all sizes typically include electronic touchpad controls and an additional remote control. As well, digital temperature readouts and energy-saver settings are the norm.

If you’re sweating out buying a new room air conditioner, start your search by assessing how much machine you’ll need. Rules of thumb:

¢ Small models (5,000 to 6,000 Btu/hr.) cool rooms 100 to 300 square feet in area.

¢ Midsized models (7,000 to 8,200 Btu/hr.) cool rooms 250 to 550 square feet.

¢ Large models (9,800 to 12,500 Btu/hr.) cool rooms 350 to 950 square feet.

Once you determine the right size, consider that the more off-center your window, the more it matters that the unit blow air where you need it. In recognition of this, we test each model to see if it directs air better to the left or right (as you face the machine), or if it has a balanced flow. Most, we found, did a better job directing air to the left.

Here are some standout models from our tests:

¢ Small: At just $130, the Frigidaire FAA067P7 qualifies as a CR Best Buy. It directs air best to the left. For a right-directed unit, try the Haier HWRO6XC5 ($165). The top-rated GE AGM06LH ($180) has a balanced flow and was our quietest small air conditioner. Each is rated at 6,000 Btu/hr.

¢ Midsized: Top-scoring in this category, the 8,000 Btu/hr. Frigidaire FAA 087P7 is a left-directing machine and – at $160 – a CR Best Buy. The 8,200 Btu/hr. LG LW8000ER ($250) blows best to the right. For a balanced flow and comparative quiet, we recommend the GE AGM08LH, an 8,000-Btu/hr. model that sells for $240.

¢ Large: Almost the performance equal of the über-efficient Friedrich SS10L10-A, the Frigidaire FAC107P1A carries a much smaller pricetag ($195) and distinction as a CR Best Buy. Like the Friedrich, it directs air best to the left. For a right-directing machine, consider the Kenmore 74107. It’s not quite as quiet as the Friedrich, but at $290 (from Sears), it costs a lot less. The LG LW1000ER ($300) was the highest-scoring of our large machines to provide a balanced flow. It, the Kenmore, and the Frigidaire are rated at 10,000 Btu/hr.

Shopping for these or other units should be a breeze, as air conditioners are such a commodity that you can buy them even in drug stores. Manufacturers list all salient information right on the box, including EER, features, and the range of window widths the unit will fit. We have found this information to be generally accurate.