Bottom freezer is covered with heavy frost. What's up doc ? [email protected]

It isn't defrosting. How old is the unit? Could be a defrost timer or the defrost heating element.

Your problem can be either in the defrost system or the fan is bad if the coils were not blocked with dirt; more than likely it’s the defrost system. If it is a “non-computer” type it has a defrost timer which turns off the fan in freezer and the compressor and energizes the defrost heater until the defrost terminator (or defrost t-stat) turns it off or the defrost timer turns it off, whichever one is first. It's a very straightforward system that is easy to work on. The electronic ones are totally different, but normally when they go bad only the heater and terminator need to be replaced. Just remove the cover to the coils in the freezer to access heater and terminator. Many times the timer is under the unit near the coils or near the t-stat in the refrigerator section. Let unit thoroughly defrost before working on it. After removing the cover to coils you will see wires leading to a heater attached to the coils. On a side-by-side the heater is a glass rod with an element inside that you can see if it is bad; on a freezer on top model it is aluminum and wrapped around the coil that will often burn apart. There is a defrost t-stat attached by wire to one side of the heater and clipped onto the coils. It is round and has two wires, one to the heater and one to the power from defrost timer. With the refrigerator unplugged turn the timer one-way plastic screw until you hear it click and stop at that point. Have the wires unplugged that attach to the defrost heater and defrost t-stat and read from the plug that supplies power to the refrigerator and the wire supplying power to heater. Put meter on ohms and put one lead on wire supplying power to heater and one to either plug prong and if timer is good you will read about zero on one of the prongs. Then put one lead on each side of heater, and if you have no continuity you need a new heater. Replace heater and terminator together and be very careful when replacing it, especially on the freezer on top model because if you bend the wrong thing you will break one of the delicate capillary tubes and lose all of the refrigerant, which will ruin the unit. If the timer is bad you will need to replace it with one that matches. You can test it before you take anything apart by advancing the timer until the refrigerator turns off. Then see if the heater defrosts the unit and then brings the unit back on; if it does not then all you may need is a new timer, but the parts are cheap, so if you need to replace the heater and terminator you should replace the timer and keep the old one for an emergency. Also, make sure to clean the coils under the refrigerator with spray soap and water; I use a quick spray from a water hose nozzle. Here are some manuals: https://dl.dropboxusercontent.com/u/8010163/Whirlpool-Kenmore%20Refrigerators.zip
https://dl.dropboxusercontent.com/u/8010163/Electrical%20Theory%20and%20Diagnosis%20of%20Major %20Appliances%20Service%20Manual.pdf
https://dl.dropboxusercontent.com/u/8010163/Whirlpool_27%20inch%20French%20Door%20Refrigerator s%20with%20Ice%20In%20Door%20Service%20Manual.pdf