Winter weather may be past, but the lingering dinginess of your home's carpets still leaves you cold. You could spot-scrub the worst of it, but if your wall-to-wall hasn't had a deep cleansing in a while (or ever), now's a good time to call in the professionals.

To find out which services are best, the Good Housekeeping Research Institute had undercover consumer testers make appointments with four leading firms. The mission for each: have two rooms of carpet cleaned, with stain-protection treatment added (since cleaning can strip the manufacturer's original finish).

Testers evaluated customer service when making the appointment, their in-home experience with the technicians and how clean the pros got their carpets.

The winners

With tying overall scores, Stanley Steemer and Sears Carpet & Upholstery Care cleaning services came out on top in Good Housekeeping's tests. Both provided the best combination of good customer service, a pleasant in-home experience and effective cleaning at a reasonable price.

Stanley Steemer did the most thorough job overall, clinching the highest combined score for completing the most tasks and leaving Good Housekeeping's testers most satisfied with the results. It was also the only one of the services that located and pre-treated stains, and explained what to do if a stain reappears in testers' homes.

Sears Carpet & Upholstery Care came in a close second and had particularly good customer service, earning top marks in appointment setup and interactions with the in-home technicians. Sears scored well for not leaving anything out of place and letting customers walk on the carpets in the expected time frame.

Stanley Steamer and Sears Carpet & Upholstery Care also were the most cost-effective, at 22 cents per square foot and 27 cents per square foot, respectively, for cleaning and stain-protection treatment — roughly 45 percent cheaper, on average, than the other two firms tested, ServiceMaster and Home Depot's Chem-Dry.

What clean means

Whether you go with a national or local carpet-cleaning company, there are a few basics to expect.

Services may require a two-room reservation or a minimum dollar amount, and costs can vary based on floor size and extras like stain-protection application or odor treatments.

During the in-home session, the technicians should offer to move furniture (small stuff for sure; larger or delicate pieces, like a china cabinet, won't be moved) or at least put protectors under furniture legs.

They also should pre-treat stains, tell you how long before you can walk on the carpet (often immediately or within an hour or two), and explain what to do if stains reappear (which can happen if the pad or backing is also stained and the unremoved matter wicks up as the carpet dries).

If your carpets are very dirty, are matted down or haven't been cleaned in ages, don't expect miracles. The technicians should say what results are realistic before they start. To keep carpets looking their best, the Good Housekeeping Research Institute recommends deep-cleaning every 12 months, or more often in homes with kids or pets.

IT'S THE VACUUMS' TURN

Maintain that professional clean with these vacuums that performed well in the Good Housekeeping Research Institute's recent tests:

Electrolux Intensity: $299; 1-800-896-9756, www.electroluxusa.com

Dyson Slim: $470; 1-866-693-9766, www.dyson.com

Halo UVX: $399; 1-877-879-4256, www.gethalo.com

iRobot Roomba: $349; 1-800-727-9077, www.irobot.com