Unit Description
27
intervals of 2, 4, 6, 8, or 12 hours. Demand defrost
cycles occur if the differences between the return
air temperature, discharge air temperature, and
coil temperature exceed certain limits. The unit
can enter defrost cycles as often as every 30
minutes if required.
Manual Defrost:
In Manual Defrost Mode, the
operator initiates a defrost cycle. See “Initiating a
Manual Defrost Cycle” on page 45.
NOTE: The unit will not perform a Manual
Defrost cycle unless the unit has been turned on
with the
O
N
key, the unit is running in
Continuous or CYCLE-SENTRY mode (or shut
down in CYCLE-SENTRY Null mode), and the
coil temperature is below 45 F (7 C).
The evaporator coil temperature must be below
45 F (7 C) to allow defrost.
The following four defrost timers are used. These
timers can be set for intervals of 2, 4, 6, 8 or 12
hours.
•
Defrost Interval In Range with Fresh Setpoint
(standard setting 6 hours)
•
Defrost Interval Not In Range with Fresh
Setpoint (standard setting 4 hours)
•
Defrost Interval In Range with Frozen
Setpoint (standard setting 6 hours)
•
Defrost Interval Not In Range with Frozen
Setpoint (standard setting is 4 hours)
This feature allows a shorter Defrost interval to be
used when the unit is out of range during a
pull-down and more frequent Defrost cycles may
be beneficial.
Normally, longer defrost timer intervals are used
for colder loads. The defrost interval may need to
be changed if the unit will not hold the
compartment temperature at setpoint.
Use a longer defrost interval if defrost is not being
initiated on demand.
Use a shorter defrost interval if defrost is
frequently being initiated on demand.
If the unit is in CYCLE-SENTRY Null mode, the
engine will start when defrost is initiated. The unit
will stay in defrost until the evaporator coil
temperature rises to 58 F (14 C).
Opening the Front Doors
Pull the door latch handle to open the doors and
access the engine compartment. Do not push the
door closed while holding the door latch handle
open or the door will not close properly.
1.
Door Latch
Figure 7: Door Latch Location
1
