This is a series circuit part that interrupts power to the heater when the temp is warm enough to melt frost on the coils. The defrost cycle is 21 minutes long. If the heater element was to stay on that long it would not be purty. So a thermostat is wired into the circuit to stop the heater once it is warm enough to melt the frost. The basic bimetal terminator closes and allows power to go through it @25f. It opens ans stops the heater when the ambient temp inside the evaporation area goes to 50f. This takes about 5 minutes or less. Most times the failure of the defrost program occurs when the bimetal separates and permanently kills the flow to the element. The defrost at first will work a little bit but the frost will linger and begin to build. After a week milk is not chilled anymore but still cold. After 2 weeks the milk is spoiled and the temps inside the fresh food section are taking a beating because the frost buildup is choking off the air flow to the fresh food compartment. Unplug the icebox and wait 4 hours and it might perk up. for a week.I worked on an icebox and found a failed bi-metal:
« Last Edit: August 01, 2012, 08:28:36 PM by JWWebster »
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