Air conditioners: cool values.(Product/Service Evaluation)(Buyers Guide)

The latest room air conditioners we tested are more energy-efficient, more feature-laden, quieter, and a better value than ever. Our Ratings of 35 units yielded CR Best Buys in all sizes.

This year's CR Best Buy for small units is $130, about $50 less than last year's best value. Prices for CR Best Buys in midsized and large models are $160 and $195, respectively, $100 less than last year's.

Price pressure on manufacturers from big retailers, plus low manufacturing costs in the Far East, where most machines are made, are fueling the price declines. Here's what else our tests reveal:

High efficiency is the norm. All models meet the energy-efficiency rating (EER) of 9.7 required for units 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 Friedrich SS10L10-A, hit the 12.0 mark, the highest we've seen a manufacturer post.

The high performance scores of energy-efficient models suggest that all air conditioners could be made to Energy Star standards. A Friedrich spokesman told us that achieving that involves pairing high-efficiency compressors with improved coil design. We were disappointed that several new models met only the minimum 9.7 EER threshold.

To find an energy-efficient model, look for a high EER and a certification sticker from the Association of Home Appliance Manufacturers (AHAM) or the Canadian Standards Association (CSA). Energy-efficient units not only help the environment but may also qualify for rebates in some areas; see the Energy Star Web site, at www.energystar.gov, for details.

Convenience features trickle down. New models in all sizes typically include electronic touchpad controls and an additional remote control. Digital temperature readouts and energy-saver settings are the norm. Other features we like include a timer and variable-speed fans that offer more options and potentially save energy Many models did a fine job handling low voltages caused by brownouts. Check "Brownout" in the Ratings for models that performed the best.

Shopping's a breeze. Room air conditioners are such a commodity that you can buy them even in drugstores. Manufacturers list all salient information right on the box, including window size, EER, and features. We have found this information to be generally accurate.

HOW TO CHOOSE

Assess your room size. A rule of thumb is that models of 5,000 to 6,000 Btu/hr. cool rooms 100 to 300 square feet, models of 7,000 to 8,200 Btu/hr. cool rooms 250 to 550 square feet, and models of 9,800 to 12,500 Btu/hr. cool rooms 350 to 950 square feet. Room construction, climate, and other factors will also affect your choice.

Consider window location. Most units did a better job directing air to the left. Check the Ratings for details.

Consider installation requirements. Many units are easy to install. But the GE models we tested were awkward. You must slide the unit out of its case to mount the side baffles. While that's a one-time issue, it may be enough to daunt you or make you pick another brand.

Clean it periodically. Clean the filter biweekly or as needed. Where possible, hose off the back of the unit if debris …