This is the component that controls how long the heater stays on when the machine is in defrost mode. Say the defrost cycle is thirty minutes, the heater may only be on for ten of those thirty minutes on the timer controls. On Adaptive Defrost Controls, when the heater shuts off, shortly after the machine exits defrost mode. Basically if the heater only stays on for ten minutes, the whole defrost cycle will only be about 12 or 13 minutes longe is continueing to build up due to one of the defrost cycle parts not fucntioning properly this is the most likely piece to be causing your ice up issue do a continuity test on the thermostat to assure that it is working properly
Basically when the heater comes on, it starts to melt the frost on the evaporator. Once all the ice and frost is gone, the temperature behind the panel will start to rise. Once the temperature behind the panel rises to a certain temperature, the thermostat will break the current of electricity going to the heater. Bam, it shuts off and prevents your freezer from becoming a sauna, or an oven. I'm sure you get the drift. The heater is on the bottom of the evaporator coils and the defrost thermostat sits on top of the evaporator coils.
This is the last component in the defrost system. This one should be pretty simple. By now if you have read this far you should already know what this does and how important is it. Some defrost heaters are a coil of wire in a glass tube under the evaporator coils. Works like a light bulb basically. The other style looks like the bake element in your stove. They both get red hot either way and melt the frost
Defrost control or timer.
Some refrigerators have a defrost timer. This type works like a clock. Every eight hours or so the machine hits the defrost spot and that's when defrost occurs
Some refrigerators have an Adaptive Defrost Control. This is what makes a refrigerator energy efficient. It varys the length of time it takes the machine to go into defrost. So instead of the energy hogging heater
coming on every eight hours, it may be 24 hours, 18 hours, 10.5 hours, who knows. It depends on how many times you have opened the doors, how long the compressor has run. This is good because the refrigerator may not need to go into defrost every eight hours. Now you are saving energy.
and lastly there is the fan also if it is not working will not allow the flow of air to leave the inside of the freezer. Continuity test can also be done on the heater as well and the least likely would be the timer to go bad in some models they have a board on the back of the machine instead of a defrost timer if you have any further questions please message me back and please remember to rank how this opinion has helped as well Thanks again Rick