The robot's intelligence is artificial intelligence, after all, which means that we humans are still smarter. As with a young child or pet, taking certain precautions enables a session to go more smoothly. Before you put the Roomba to work, you need to pick up all stray objects on the floor--loose cables, stray socks, last night's magazine--and, for the best results, move small pieces of furniture that may complicate its navigation. Objects that could be easily toppled--a small houseplant, for example--should be moved from the Roomba's path. The manufacturer recommends the appliance for hard surfaces--wood, tile, linoleum, and low carpets--and advises that it not be used for deep pile or shag carpeting. I found that in one room, the Roomba moved without difficulty from wood to a medium-pile carpet and back again, while in another, it could not move from wood to a low carpet with fringe. Although the manufacturer suggests that such problems can be remedied by turning fringe under, the Roomba was not able to make the "leap" from the wood floor to the carpet once the edge was rolled under and thus thickened. A good solution to this situation was to place the virtual wall unit at the edge of the problematic carpet, allowing the Roomba to sweep all the room except the area where it could encounter trouble. The virtual wall unit is a small box that sends an infrared beam that the Roomba translates as a barrier. To operate it, you simply turn it on, select the length of "wall" you wish to create from three options (defined in the manual), and aim the unit's eye in the desired direction., Open Access Door To Verify A Frozen AC Unit. I recommend that homeowners first verify that the air conditioner is actually frozen. When AC’s freeze up, the air from the vents will usually be warm or have very little airflow.This happens when the evaporator coil is frozen, because it blocks air from the blower from pushing through the supply ducts., After every 10 uses (5 in households with pets or long hair), the unit needs to be cleaned. Removing the dirt tray or "particle bin" after every use is simple; just press down and slide it out, shake the dirt into the trash, and slide it back in. Cleaning out the filter chamber is almost as easy--just a matter of snapping open a door and .