How do I oil and Clean the Whirlpool dehumidifier Model AD0402XS

Mary,
There is a recall on Whirlpool dehumidifiers that may cover your unit, the website lists serial numbers of units on the recall list.
Dehumidifier Recall FAQs
I assume from your question that at least the fan is running. There are many reasons why a dehumidifier is not removing water from the air. Most likely is accumulation of dust and pet hair that restricts the air flow. If you can, unplug it, take off the covers and vacuum out all the dirt from the evaporator and condenser (little radiator like parts). This website has some good blow up pictures of how it is put together and part nomenclature:
WHIRLPOOL DEHUMIDIFIER Parts Model AD25J3 SearsPartsDirect
If the air flow is restricted, the compressor has to work harder to the point that the overload gets tripped. It may or may not be resettable; it is part #10 in the diagram on this page:
http www searspartsdirect com Whirlpool Dehumidifier Parts Model AD25J3...
If you do take the covers off, check that the fan turns freely and you may want to add a drop of oil to each end of the motor if there is a place to oil it. Light oil like sewing machine oil or light engine oil will do.
You cannot really tell if the compressor is working with all of the covers on; and I cannot recommend plugging it in with covers removed because there may be open electrical connections that you do not want to touch. However if the compressor is running, the outlet tube will get hot; that is the one that goes to the condenser [radiator like bundle of tubes nearest the fan] [it may get too hot to touch]. The evaporator [bundle of tubes farthest from the fan] should start to get cold where the tiny little tube from the condenser joins. If neither is happening and you are sure the compressor is running, it is out of refrigerant [freon] and may or may not be worth fixing. If the evaporator ices up [gets covered with frost] it may be low on refrigerant indicating a leak; again it may not be worth fixing.

Might be a dirty coil and condenser.
I have had a AD75UST0 WHIRLPOOL Dehumidifier for several years. If it actually still runs, I would suggest you take off covers and give the coils a good thorough cleaning. Otherwise the units are not designed to be serviceable aka - "disposable small appliance". if you do dispose of it take it to a qualified recycle organization for Freon products. Shut unit off. Remove "bucket". You should find a "tab" at top of where bucket goes in middle front of unit. Pull down to remove tab of Filter. Clean thoroughly and dry Filter before re installation. Visually inspect the coils and condenser while filter is out ( a flashlight helps). If it looks slightly dusty or like covered in felt, then it would be wise to remove front and rear covers and give the coils and condenser a thorough cleaning.

WHIRLPOOL DEHUMIDIFIER Parts Model ad75ust0 Sears PartsDirect

Check fans etc all clear and running full speed. May be short of gas

Kim, it may simply be a case of the humidity extraction level being set to HIGH. Lower it to 35%. If it's an analog unit (No LED Display) turn the humidity extraction knob to Maximum. More often than not, this will solve the problem. If it doesn't the humidity sensor may need to be replaced.

I hope this helped you and thanks for choosing FixYa.

Look on the each end of the motor. If you see a rubber plug that you can remove then it can be oiled. More than likely you will find none. The vast majority of electric motors today are sealed for life and there is no provision to add oil.

How can not get water to flow from the bucket through the water hose when the hose is attached.

Take the unit outside and wash the coil out with a garden hose. Careful not to get water on the controls. Water will not hurt the motor or compressor as long as you keep it unplugged. Allow the unit to completely dry before running it again.

I have a Whirlpool dehumidifier model AD50LJ0: the compressor starts but then appears to trip out. The fan keeps running. It does not condense and water. Can you help?

Make sure the coils are clean. (check the inside part of the coils. If they look ok then see if your compressor is running. if its not running then it could be any number of things. I recommend that you have a pro look at it

If a dehumidifier seems incompetent, it may be undersized for the space. Check the unit's specifications to be sure it can handle the room size. If you don?t want to replace it with a larger one, try closing doors and dehumidifying your space a section at a time. You can also: 1) Disconnect the power cord. 2) Remove the cover and clean the condenser and evaporator coils, as discussed above. 3) Lubricate the fan motor bearings with a couple of drops of oil if the motor has oil ports (some units don't need to be oiled). While you?re at it, make sure that the condenser isn?t clogged with dust or dirt. 4) If it still operates poorly, call an appliance repairperson for advice or take the unit into an appliance repair shop.