Researching reasons for the freezer to not defrost, there were determined to be three potential causes: malfunctioning defrost timer, defective bi-metalic switch, or a defective defrost heater element. Research indicated that the most common source of the issue was a malfunctioning defrost timer. So, I purchased the defrost timer (which was the lowest cost option) and installed it, which took about 30 minutes. I would rate the replacement effort as "easy". Most of the time was spent collecting the proper tools and planning the repair. When placed back into service, the freezer did not appear to begin defrosting. I gave it about two days, and based upon visual evidence that the problem was NOT fixed, I removed the panels in the freeze to inspect the bi-metallic switch and the defrost heater. Using a VOM, I determined that the heating element was good; however, the bi-metallic switch appeared to be failed open, even after placing the switch in ice water while testing for continuity. So, I ordered a new bi-metallic switch which included a wiring harness. It took about 4-5 days to diagnose the problem, order, and receive the new switch. During this time, I did not have cause to inspect the freezer. Once received, I collected the needed tools and opened the freezer, only to find that the freezer was fully defrosted! So, in the final analysis, the defrost timer was the culprit! It apparently took 4-5 days for the defrost timer to cycle enough times into defrost to effect the true defrost of the freezer. Lesson learned: give the defrost timer time to do its job!
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