Dehumidifiers need little upkeep or care. The following simple procedures are sufficient:
Always unplug the power cord before cleaning the unit. For regular cleaning, dust the grilles or louvers with a soft brush or the dusting attachment of a vacuum cleaner. Either dust the cabinet or wipe it with a damp cloth. Every few weeks, scrub the inside of the water container with a sponge or soft cloth and a mild detergent to discourage the growth of mold, mildew, or bacteria. At least once each season, remove all dust and lint from the cold coils with a soft brush.
Always plug a dehumidifier into a three hole grounded outlet. If there is none where you want to put the unit, make sure you install one properly. Using extension cords is not advised because if an extension rests on a damp floor or if water spills on it, is a shock hazard. If you must use an extension cord, be sure it has a three-hole receptacle and three-prong plug for grounding. If a three-hole, grounded outlet is not available, convert it following our instructions and grounding properly. This is particularly important for a dehumidifier because it may be operated on a damp floor that could conduct electricity and because it collects water, which could spill and cause an electrical accident. Never remove the third prong from a dehumidifier plug; to do so invites an electrical accident. This article has been contributed in part by Michigan State University Extension
A dehumidifier's fan motor should either be permanently oiled or easy to reach for oiling; the refrigeration system motor is sealed and never needs oiling.
Information courtesy of http://www.msue.msu.edu/portal/