LG LFX31995ST Training Manual page 112

Defrost Circuit
LFX31995ST Refrigerator
Defrost circuit
The LFX31995ST being a dual evaporator refrigerator has two defrost
heaters and two thermal fuses as safety devices along with three defrost
sensors.
The refrigerator heater is a 160 watt heater with a thermal fuse that
opens @ 171°F. To OHM out from CON3 on the Main Power Control
Board (PCB) check between YL & BL, 80-90 . At 1.3 amps.
The freezer heater is a 300 watt heater with a thermal fuse that opens
@ 162°F. To OHM out at CON3 on the PCB check between BO & BL,
40 to 50 . At 2.5 amps. Note: the freezer evaporator has two defrost
sensors.
Defrost is controlled by the Main Control Board taking in many factors
such as time since last defrost, room temperature, humidity, door
openings and duration of openings.
When defrost is initiated both heaters are energized if both defrost
sensors are below 46°F. If one sensor exceeds 46°F the power is
removed from that heater and the other heater continues to heat until
46°F is sensed by it's defrost sensor.
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