Autoshutoff does not work

Nine times out of ten, a problem with a dehumidifier can be traced to electrical parts-not to the compressor. If the problem is being caused by the compressor and the unit is out of warranty (most have a 1-year limited warranty), strongly consider replacing the unit rather than trying to have the compressor repaired. If you're thinking about having the unit repaired, be sure to ask for an estimate.

Unless it is designed to drain automatically, a dehumidifier should be emptied fairly often during hot and muggy or damp weather- sometimes as often as once a day. In humid, damp climates, a dehumidifier's reservoir can pull as much as 50 pints of water from the air a day. Failure to keep the reservoir clean and dry will just contribute to the problems you're trying to solve. If you're in the market for a new dehumidifier, consider its reservoir capacity: Larger capacity reservoirs work more efficiently and have to be emptied less often.
Many dehumidifiers have a float switch that prevents the unit from spilling over with the water that has been drawn out of the air. Sometimes this switch goes bad and must be replaced. If your dehumidifier is overflowing, you can test the overflow prevention switch with a volt-ohm meter.
1) Unplug the dehumidifier and remove the switch.
2) Disconnect the leads and clip the leads to the terminals on the switch.
3) Check the pan or reservoir and empty it if necessary, or make sure the drain isn't clogged.
4) Straighten any kinks or bends in the unit's hose.
5) Set a volt-ohm meter to the RX1 scale (or to K-ω or ω resistance on a digital meter) and depress the bar or trip lever on the switch. If the meter's needle shows no continuity as the switch is clicked back and forth, the switch is probably faulty and will need replacement.