Pump not working - DeLonghi DH40P Dehumidifier

id be inclined to think that for some reason the pump is taking too long to pump tank out (or it thinks it is ) this would cause the fault you describe and the safety control shuts pump off for fear of a problem

I think this means your pump is not working, and therefore the tank is full. The pump could just be switched off, could have failed, or could be clogged. See the other messages regarding this model, for an excellent description of how to clean out a clogged pump.

A blocked drain tube was the cause of the pump not working issue with this dehumidifier. I removed the back cover (5 screws on back, 1 screw on each side) and cleaned out the accumulated gunk in the small, clear reservoir on the back right. It took a little time using compressed air and pipe cleaners, but the effort ultimately worked.

The pump and water level sensor are one piece replace the pump.

This will work for all models. You just need to get a condensate pump. Hook drain from dehumidifier to the condensate pump. the dehumidifier will need to be higher than the pump so it can drain.

I only got as far as disconnecting the filter between the small water bucket and the pump. I was able to get the pump working again after I cleaned the water bucket and filter by flushing them repeatedly with fresh water. The lines after the pump contained cloudy water, but I figured since the pump was able to push it out past the pump already, it shouldn't cause problems this far down. It saved a lot of time and hard work not having to disconnet the rest of the tubing or take the water bucket off. I also realized if I disconnet the first water collection tubing from just under the front panel and point the open end down, all the water in the bucket flows out. This part is so easy to get to. Just pull out the big collection tank and it's right there on the left toward the back. I can do this every week! Maybe then nothing will sit long enough in the small water bucket to turn into any kind of filter-clogging material.

It's not a one way valve, it's a water strainer. It has a barrel with a fitting on each end, the upper leads into the barrel, the lower has a strainer tube attached. When it's plugging up, it seems like a one-way valve because when you try to force water into the top, it pushes the lint and junk against the strainer screen, blocking it. When you try to force water in from the bottom, the water pushes the lint away from the screen, allowing a reduced flow. Some have an arrow; it's to indicate flow direction to keep the lint on the outside of the screen; the inside, being mush smaller than the barrel, would plug up much sooner. Before you replace the strainer, clean the lint & stuff out of the small pump reservoir (above the pump). If you don't, the strainer will plug up quickly again, if it can even get water to it.

Dehumidifiers and how they work
Heat pump dehumidifiers

Dehumidifiers use a heat pump (similar to an air conditioner's heat pump) or chemical adsorbents to remove moisture from the air without cooling the air.

A heat pump dehumidifier uses a fan to draw indoor air over a heat exchange coil. The coil is almost freezing. The water in the air condenses on the coil and is drained. A second heat exchange coil reheats the air, which the dehumidifier exhausts into the room.

A heat pump dehumidifier dumps heat lost from the compressor and fan motors into the air. It returns to the indoor air the heat generated by the dehumidifier turning water vapour to liquid. I got this off the internet

I had a similar problem with the pump not working and the water flowing into the main drainage bucket instead. I had to disassemble the housing...not an easy project to reassemble...and found that the pump has its own smaller drainage tank with a float device, a pump pre-filter, the actual pump, then of course, more drainage tubes. The entire pump drainage system of components needed cleaned of accumulated, mucoid, slime! I cleaned the channel in which water flows into the pump's tank...located on the screen filter side of the dehumidifier. Then I moved to the other side of the dehumidifier and cleaned-out the entire pump drainage tank. Note that the pump's drainage tank only empties about 1/2 inch of water each time the pump activates. Thus, there is always alot of water in the pump's drainage tank. Thus, alot of time for slime to accumulate. Next, I cleaned off the float mechanism. I then cleaned-out the pump's pre-filter. Cleaning out the pump's pre-filter was paramount to the pump functioning properly and quietly! I checked that my pump was properly installed and NOT rubbing against its mounting so that it operated quietly. I added fresh water to the pump's tank several times to insure that the pump was working properly and that all slime was eliminated. Finally, I reassembled the housing...not an easy task! My pump now functions like new. All this work had to be done to insure proper function of the dehumidifier's pump system. My dehumidifier is only 11 months old. It is still covered by the one year warranty, but it is too expensive to ship the entire unit, as Delonghi requires you to do at your expense for them to fix it under warranty. You can be assured that I will check for future slime build-up to keep my dehumidifier functioning properly. The dehumidifier works great, it's just that it's high maintenance.

I have the same problem. Very annoying. My suggestion is to go to your nearest dealer and throw the unit through their front window.