John called a repairman, who arrived a few hours later with a toolbox and a diagnosis: the defrost drain was clogged. Apparently, the drain, which was supposed to carry melted ice and water out of the fridge and into a pan at the bottom, had become blocked by a chunk of ice and debris. The repairman explained that this was a common issue, especially in older fridges.
As a precautionary measure, the repairman also checked the fridge's defrost timer and heating element, ensuring they were functioning correctly. He also recommended that John regularly clean the fridge's drain and condenser coils to prevent future issues. defrost drain fridge