How does a frost free refrigerators defrost system work?
There are many separate components in a refrigerator’s defrost system that must work in consort for a frost free system to work properly. We will attempt to explain the workings using simplified electrical schematics. The heart of the defrost system is the defrost timer. The timer is a motorized device that opens and closes electrical contacts. Each contact can be thought as a light switch, one controls the defrost cycle, the other the cooling system. When one of these is switched on, the other is switched off. A motor on the timer (NOT illustrated) turns a cam that opens and closes these contacts at set intervals (see below for other types). Cooling Cycle During the cooling mode, the defrost timer closes a contact to the compressor circuit so it will run. The circuit to the defrost heater is open. While in this mode, the thermostat (a.k.a. cold control) cycles the compressor and fan motors on and off to maintain an appropriate temperature. Defrost Cycle The defrost timer eventually sw
There are many separate components in a refrigerator’s defrost system that must work in consort for a frost free system to work properly. We will attempt to explain the workings using simplified electrical schematics. The heart of the defrost system is the defrost control. The most common control is a mechanical defrost timer which is a motorized device that opens and closes several electrical contacts. Each contact can be thought of as a simple light switch but instead of a light, one connects the defrost heater circuit, another connects the cooling system. When one of these is switched on, the other is switched off. A motor on the timer (NOT illustrated) turns a cam that opens and closes these contacts at set intervals (see below for other types). Cooling Cycle During the cooling mode, the defrost timer closes a contact to the compressor circuit so it will run. The circuit to the defrost heater is open. While in this mode, the thermostat (a.k.a. cold control) cycles the compressor an
