4–9
T-372
4.3.16
Frozen Idle Mode
When temperature drops to setpoint minus 0.2°C (0.4°F) and the compressor has run for at least five minutes, the
unit will transition to the Frozen Idle Mode. The compressor is turned off and the evaporator fans continue to run to
circulate air throughout the container. If temperature rises above se0.2°C (0.4°F), the unit will transition back
to the Frozen Steady State Mode.
Figure 4.7 Controller Operation - Frozen Mode
4.3.17
Frozen “Heat” Mode
If the temperature drops 10°C (18°F) below setpoint, the unit will transition to the Frozen “Heat” Mode. The evapo
-
rator fans are brought to high speed, and the heat from the fans is circulated through the container. The unit will
transition back to Frozen Steady State Mode when the temperature rises back to the transition point.
4.3.18
Frozen Economy Mode
In order to activate Frozen Economy Mode, a frozen setpoint temperature must be selected, and Cd34 (Economy
Mode) is set to “ON.” When this mode is active, the system will perform normal Frozen Mode operations except
that the entire refrigeration system, excluding the controller, will be turned off when the control temperature is less
than or equal to the setpoint -2°C (4°F).
After an off-cycle period of 60 minutes, the unit will turn on the high speed evaporator fans for three minutes, and
then check the control temperature. If the control temperature is greater than or equal to the frozen se0.2°C
(0.4°F), the unit will restart the refrigeration system and continue to cool until the off-cycle temperature criteria are
met. If the control temperature is less than the frozen se0.2°C (0.4°F) the unit will turn off the evaporator
fans and restart another 60 minute off-cycle.
4.3.19
Frozen Mode Cooling - Sequence of Operation
a. When the return air temperature is above setpoint and decreasing, the unit will transition to economized
cooling with the condenser fan motor (CF), compressor motor (CH), economizer solenoid valve (ESV), low
speed evaporator fan motors (ES) energized and the white COOL light illuminated. (See
).
b. When the return air temperature decreases to a predetermined tolerance above setpoint, the green IN
RANGE light is illuminated.
Controller Set Point at or BELOW
ï
10
q
C (+14
q
F),
or
ï
5
q
C (+23
q
F) optionally
ï
.20
q
C
+.20
q
C
Air Circulation
Cooling,
Economized
Set Point
+2.5
q
C
(+4.5
q
F)
Frozen Mode
Falling
Temperature
Rising
Temperature
