Some basic operational facts:
Think of a refrigerator as a window air conditioner. If the cold setting is too high, the coils through which cold air must pass will ice up if they are not given time to defrost. So if the defroster isn't cycling on and off correctly, it will fail to defrost the coil and the coil will become ice-covered and the fan will not be able to push air through the accumulated ice (which is on the coil in the freezer section behind the thin metal cover at the back of the freezer). Ironically, the freezer will still be cold, even if the ice covers the coils. But without periodically defrosting the coil, the small fan won't be able to blow cold air from the freezer section to the refrigerator section of the appliance.
For the temperature sensing control and the defrost timer to function, the two components of the defroster heater located in the freezer section must also be functioning correctly. For DIY technicians, it makes sense to replace the electrical components on both sides of this freezer/refrigerator combination. The DIY cost of all four parts is less than $150. So, if the compressor, heat exchanger coil, and two fans are functioning correctly, the appliance will run like new when these four new parts are installed.
I replaced the two switches controlling the defrost cycle. These are the "defrost timer switch" and the "temperature (sensitive) control switch", both of which are located in the upper portion of the refrigerator section of the appliance just above the light bulb socket behind the housing assembly containing the two controlling slide switches (or knobs on some models) for freezer temperature and fresh food temperature.
Appliance Parts Pros show how simple it is to replace the timer. There is no video for the defrost temperature control thermostat, which is more challenging to replace. The reason the defrost thermostat is more challenging is because it must physically link with the geared nylon wheel that connects the refrigerator temperature control lever (slide or knob) to the shaft of the temperature control device.
Also, the replacement temperature control is slightly different from the original control The original has a temperature sensing coil attached to the temperature switch and this coil is a spiral shaped thin piece of wire that is part of the switch. The replacement part arrives with this coil correctly attached to the temperature sensor, but it is in an undefined shape looking like a straight but flexible piece of wire. Gently coil this wire in a spiral shape to approximately match the appearance of the original part. It is easier to do this before you install the new temperature sensing control.
To access the screws to remove the old temperature sensing control, you will need to move the sliding controller lever to the extreme left and right to access the first one screw and then the other screw. The sliding controller will need to be in the far-right position after installing the new temperature controller. And the controller shaft will need to be in the most clockwise position to match up with the sliding controller lever when you reinstall the cover.
Remember that the screws securing the temperature controller to the housing of the controller must go through both the plastic control lever housing and the metal housing for both the temperature controller and the timer. So, if the original screws do not match the threads on the replacement temperature sensing switch, remember the original screws only need to grab about 1/8 of an inch of the metal on the new temperature sensing switch to secure the switch. Carefully tightening and loosening the screws on the replacement part several times should be enough to modify the differences in the thread gauge so the original screws will work.
Once you have the defrost temperature control correctly installed, you can replace the timer. The defrost timer is very much like the $6 timer you can buy at Walmart or Target to turn the lights on and off in your house. Appliance Parts Pros provide an accurate and easy to follow install video for this timer. But they don't tell you that the new timer is likely to arrive with a setting that is "off." Consequently, when you correctly install it, reinstall the controller and timer assembly, and put the light bulb back in the socket, the refrigerator may not operate. Relax.
Look closely at the small wheel that is visible on the front of the housing for both the temperature sensor and the timer, and you will see that there are two tabs on the tiny wheel that is visible just above the light bulb socket. If you have saved the old-timer you can experiment with it. Look closely at this wheel on the old part and you will see the same small tabs. You could put a screwdriver (or a thumbnail) next to this wheel and if you get the position correctly, you can turn the timer one click at a time clockwise. One-click is all it needs to turn the refrigerator on. It will manage the clock on its own after you start it. Or you can just wait 14 hours and it will start itself.
Some basic operational facts:
Think of a refrigerator as a window air conditioner. If the cold setting is too high, the coils through which cold air must pass will ice up if not given time to defrost. So if the defroster isn't cycling on and off correctly, it will fail to defrost the coil and the coil will become ice-covered and the fan will not be able to push air through the accumulated ice which is on the coil in the freezer section behind the thin metal cover at the back of the freezer. Ironically, the freezer will still be cold, even if the ice covers the coils. But without periodically defrosting the coil, the small fan won't be able to blow cold air from the freezer section to the refrigerator section of the appliance.
For these two parts to function, the two components of the defroster heater located in the freezer section must be functioning correctly. For DIY technicians, it makes sense to replace the electrical components on both sides of this freezer/refrigerator combination. The DIY cost of all four parts is less than $150.
If the compressor, heat exchanger coil, and two fans are functioning correctly, the appliance will run like new when new four new parts are installed.
Good luck!