8
Electronic Functional Description
Adaptive Defrost Operation
Defrost occurs after predetermined length of
compressor run hours. Compressor run time
between defrost changes, or adapts, depending
upon recent history of defrost lengths (time it
takes for defrost terminator to open after defrost
heater has been turned on).
•
Defrost terminator opens at 55
°
F (-
13
°
C).and closes at 20
°
F (-7
°
C).
•
Compressor run time between defrost
(CRDT) will be one of 3 values under
normal operation CRDT 1 (8 hours) or
CRDT 2 (12 hours) or CRDT 3 (15
hours).
If defrost length is low (DT-LO defined
as 21 minutes) indication small frost
load, CRDT for next defrost cycle is
advanced to next level.
If defrost length is high (DI-HI defined
as 24 minutes) indicating large frost
load, CRDT for next defrost cycle is
lowered to next level.
If defrost length is between 21 and 24
minutes, CRDT for next defrost cycle
remains the same.
Initial value at power up CRDT is 4 hours.
•
Vacation Mode CRDT equals 96
hours. Vacation Mode CRDT is
interrupted with door openings.
Defrost interval will revert back to
interval before vacation mode.
Three things must occur to reach
Vacation Mode CRDT.
1) Defrost interval must be
CRDT 3 (16 hours).
2) Both
refrigerator
and
freezer doors must have
remained closed since last
defrost cycle.
3) Defrost thermostat must
have opened in less than 21
minutes during last defrost
cycle.
•
Six minutes dwell time occurs after
defrost terminator opens before
compressor and condenser fan
motor will operate. Ten minutes
dwell time occurs after defrost
terminator opens before evaporator
fan motor will operate. Dwell time
can be bypassed be disconnecting
power to the unit for 30 seconds.
•
Conventional defrost can be selected
in Program Mode B.
