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During the cooling operation, the main control
board monitors both fresh food door openings,
freezer drawer openings and compressor run times.
The board counts the time that the doors are open,
and reduces the length of time between defrosts
by 1,260 seconds (multiplication factor) for each
second that door is open. If the freezer drawer and
fresh food door(s) are open at same time, the time is
doubled. One or both fresh food doors are counted
as one. The door open times with the multiplication
factor reduces compressor run time by that amount.
If the doors are not opened, the compressor will run
up to 96 hours between defrosts. If the doors are
opened frequently and/or for long periods of time,
the compressor run time between defrosts will be
reduced to as little as 9 hours.
Example: If between defrosts the fresh food was
open for a total of 2 minutes and the freezer was
open for a total of 1 minute, the compressor run
time between defrosts would be reduced by 63
hours.
When the main control board determines that
defrost is necessary, it will force the refrigerator into
a continuous cool mode called pre-chill. During pre-
chill, the freezer temperature may be driven below
the set point. However, the fresh food temperature
will be regulated by the evaporator fan running at
low speed. Pre-chill will last up to 60 minutes. These
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pre-chill. This will reset the pre-chill time back to 60
minutes. After 8 hours of pre-chill the defrost heater
will be activated even if the doors are opened.
After the operation, the main control board turns
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compressor, condenser fan, and evaporator
fan. During defrost operation, the main control
board monitors the evaporator temperature
using evaporator thermistor inputs. Typically, the
evaporator thermistor will sense a temperature of
45°F within approximately 16 minutes. When the
thermistor senses 45°F, the main control board
will terminate the defrost heater operation. The
maximum defrost cycle (heater on) time is 35
minutes (main control board time out). The defrost
system is protected by a safety over-temperature
thermodisc (bimetal switch). The thermostat opens
when the evaporator temperature rises to 140°F
and closes when the evaporator temperature
lowers to 110°F.
Defrost System
Adaptive Defrost
Adaptive Defrost (Cooling Operation)
Adaptive Defrost (Pre-Chill Operation)
Defrost Heater Operation
Dwell Period
Adaptive Defrost is a defrost system that adapts
to a refrigerator’s surrounding environment and
household usage. Unlike conventional defrost
systems that use electromechanical timers with a
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Defrost utilizes
electronic controls to determine when the defrost
cycle is necessary. In order to accomplish the
optimum defrost cycle time, the main control board
monitors the following refrigerator operations:
• Length of time the refrigerator doors were open
since the last defrost cycle
• Length of time the compressor has run since the
last defrost cycle
• Amount of time the defrost heaters were on in
the last defrost cycle
Adaptive
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Those operations are:
• Cooling
Operation
• Pre-Chill
Operation
• Defrost Heater Operation
• Dwell
Period
• Post
Dwell
After the defrost heater operation has been
terminated by the main control board, a 10
minute dwell period occurs. During this period, the
compressor, condenser fan, and evaporator fan
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evaporator will continue to drip and drain so that,
prior to the cooling operation, the evaporator will be
totally clear of any moisture.
At the end the dwell period the compressor and fans
are restarted and the cooling cycle begins again.
