My 13 year old Amana bottom freezer refrigerator stopped defrosting, and the refrigerator warmed up as the frost accumulated. A repair technician told me it was most likely a faulty defrost thermostat that was causing the problem. His estimate for a repair was about $300. He suggested that I might want to try replacing the thermostat myself as it was not very difficult. I located the part at appliancepartspros.com, and placed the order in the afternoon. Late the next morning the part arrived via FedEx. It took me about 30 minutes to replace the thermostat, and the refrigerator is working good as new! Price for the part? $36, including that amazingly fast shipping!