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Humidity Sensor
This device senses the humidity in the kitchen and
assists the control board in adjusting the wattage
outputs of the 3 mullion heaters accordingly.
The humidity sensor receives 5 VDC from the
main control board and sends back 1 to 3.6 VDC,
depending on the relative humidity. There is no
resistance check for the humidity sensor.
The humidity sensor is contained in a housing that
is attached to the front of the base with a Phillips-
head screw.
To access the humidity sensor, it is necessary to
remove the 2 Phillips-head screws and the base
grille from the refrigerator.
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Humidity Sensor
Mullion Heaters
The refrigerator utilizes 2 AC mullion heaters and
1 DC mullion heater. They are the articulating door
mullion (DC), freezer/fresh food mullion (AC), and
freezer face DD (Double Drawer) mullion heaters
(AC).
The 3 mullion heaters are controlled by the main
board software logic. The main control board takes
into account the percentage of room humidity,
room temperature, and either freezer or fresh food
temperatures. As the room humidity increases,
the amount of voltage supplied to the heaters
is increased to keep the mullion surfaces from
sweating. At lowest humidity, the articulating door
mullion and freezer/fresh food mullion may turn off
completely, but the freezer face DD mullion heater
will always have some voltage present.
If the energy saver is off, all heaters are on.
When the energy saver is on, the articulating door
mullion and the freezer/fresh food mullion are off.
The freezer face mullion heater is on at a lower rate.
The freezer face DD mullion heater will not operate
with either freezer drawer in the open position.
Every 20 minutes, the main control board utilizes a
"duty cycle" to monitor and react to the condition
of the humidity sensor. Control board corrections, if
needed, are made at a speci
fi
c time period during
the duty cycle.
If the control detects a failed humidity sensor, and
the energy saver is off, all mullion heaters will be
operated at 100%.
If the control detects a failed humidity sensor, and
the energy saver is on, the freezer drawers mullion
heater will be operated and cycle at a rate of 21%
on time and 79% off time. The articulating door and
freezer/fresh food mullion heaters will remain off.
Sweat or frost on mullion surfaces indicate
malfunctioning heaters, wiring, or control board.
Humidity Sensor-Front View
Humidity Sensor-Rear View
