Take a vacuum cleaner or shop vac and slide on a brush-head attachment. This is the most efficient way to clean objects with complex construction and many irregular surfaces, like the inside of a radiator. The brush attachment will dislodge dust and debris on the fins, which can then be sucked up by the vacuum. You may be able to dust your unit without the use of a brush attachment (or with another device like a hand vacuum), but it will take longer and won’t be as thorough. Turn on the vacuum and place your hand over the hose to make sure it’s getting proper suction. Run the brush head along the length of the radiator pipes and fins, using long, sweeping motions to collect as much dust as possible. Go over the fins as many times as you need to until you’re satisfied with their condition.  Brush around the fins in both directions, across the tops and down the sides. If your unit is particularly dirty, wipe away cobwebs, dust bunnies and clumps of hair with a dry cloth or paper towel before vacuuming. In some cases the bristles of the brush attachment may not be long enough to penetrate the spaces between the fins. If this is the case, use a separate tool, such as a slender paint brush or pipe cleaner, to work the stuck-on dust and dirt out of the deeper crevices of the unit’s innards.  Cleaning between the fins can be a tedious process, but it’s worth it to save yourself the expense of a poorly-running radiator. Some people claim to have had success loosening stubborn buildup with a spray bottle of water. This is not recommended, as it may cause rust or damage your unit. Depending on how dirty the radiator cover face plate is, you might decide to clean it as well. Wet a washcloth with warm, soapy water. Scrub the inside of the cover to loosen any caked-on grime. Rinse and rewet the washcloth, then wipe away any remaining debris.  This step will be especially important if you used your radiator cover to catch stray debris. Treat rusted metal covers with a rust-remover solution before replacing them. Lift the cover and position so its back side faces the wall. Set the cover down in the groove at the top of the unit’s base, then lower it over the radiator until it fits back into place. It may click or snap to let you know it’s secure.
Ready a vacuum cleaner with a brush attachment. Vacuum out the inside of the unit. Remove hard to reach debris with a separate brush. Wipe down the radiator cover. Replace the cover.