Adaptive Defrost Operation - Viking VCBB360R Service Manual

Electronic Functional Description

Adaptive Defrost Operation

Defrost occurs after predetermined length of
compressor run hours.
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.
Compressor run time
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
Three things must occur to reach
Vacation Mode CRDT.
1) Defrost interval must be
2) Both
3) Defrost
•
Six minutes dwell time occurs after
defrost terminator opens before
compressor
motor will operate.
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.
8
before vacation mode.
CRDT 3 (16 hours).
refrigerator
freezer doors must have
remained closed since last
defrost cycle.
thermostat
have opened in less than 21
minutes during last defrost
cycle.
and condenser
Ten minutes
and
must
fan