Carrier Transicold X4 7300, Operation & Service Manual

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62-11637 4–14
Once the control system detects that the ambient tem-
perature has dropped below the pre-programmed tem-
perature, the unit will switch into ProductShield Winter
which will force the unit to operate in Continuous Oper-
ation. The unit will continue to operate in Continuous
Operation for a minimum of 30 minutes. After 30 min-
utes, the unit will return to auto Start/Stop if the ambi-
ent temperature has risen above the pre-programmed
ProductShield Winter temperature.
d. ProductShield Fresh:
When the unit is operating with the FreshProtect Func-
tional Parameter active, the ProductShield Fresh Con-
figuration may be used to override the FreshProtect
setting when the unit is operating under high ambient
conditions.
Operation in ProductShield Fresh is controlled by three
Configurations; PRODUCTSHIELD FRESH, PROD-
UCTSHIELD FRESH TEMPERATURE and PROD-
UCTSHIELD FRESH PROTECT.
The PRODUCTSHIELD FRESH Configuration may be
set to OFF or ON. With the Configuration set to ON, the
override is allowed.
The PRODUCT SHIELD FRESH TEMP Configuration
may be set from 70 to 90°F (21 to 48°C). The override
will be allowed when ambient temperature is above the
setting. The unit will return to the FreshProtect setting
when the ambient falls to 3.6°F (2°C) below the setting.
The PRODUCT SHIELD FRESH PROTECT setting
establishes the overriding limit on how far below set-
point the supply air temperature can drop. The settings
displayed for selection will depend on the FreshProtect
Functional Parameter setting for this application. Only
the values that allow less temperature drop will be
available for selection. For example, if the FreshProtect
Functional Parameter is set to C, then the Product-
Shield FreshProtect overrides displayed for selection
will be A & B.
NOTE
All of the ProductShield settings may be
viewed in the Data List (Refer to Section
3.13 ). For units with IntelliSets, the Data List
will reflect the ProductShield settings for the
IntelliSet that is currently active.
4.10.4 Air Flow
AIR FLOW Functional Parameter may be set to place
the unit in continuous high air flow when the setpoint is
in the perishable range. The Parameter may be set to
NORMAL or HIGH. The factory default setting is NOR-
MAL.
Some products generate a considerable amount of
heat (heat of respiration) during transportation. This
frequently occurs with produce. The HIGH selection
can be used for these loads, since continuous high air
flow may be required to keep the entire load at a con-
stant temperature. The engine will remain in high
speed when HIGH is selected, unless a low speed
override (refer to
Section 4.11.2 ) is active.
4.11 PREPROGRAMMED SOFTWARE OVER-
RIDES
4.11.1 Cargo Protect Mode
The control system will activate Cargo Protect Mode
when the A00122 - “CHECK RETURN AIR SENSOR”
and A00123 - “CHECK SUPPLY AIR SENSOR” alarms
activate at the same time.
• If the setpoint is in the perishable range (refer to
Section 4.5.2 ), the unit will shutdown.
• If the setpoint is in the Frozen Range the engine
will go to low speed.
The MessageCenter will display “WARNING: NO TEM-
PERATURE CONTROL” when the unit is operating in
Cargo Protect Mode.
4.11.2 Engine Speed Overrides
This section lists the different factors that determine
engine speed (high or low) in addition to the speed
controls used in temperature control.
Speed Control Overrides in priority order are:
1. High Ambient.
If ambient temperature is 120°F (48.9°C) or above
during the engine starting sequence, the unit will run in
low speed for the first 2 minutes of operation. This
applies to Heat and Cool modes only - not Defrost.
2. Low Suction/High Discharge Pressure.
If UL1 has unloaded and the suction pressure is less
than 3 PSIG (0.2 bar) for at least 20 seconds or the dis-
charge pressure is greater than the calculated maxi-
mum for more than five seconds, the engine will be
forced to run in low speed for a minimum of five min-
utes. After five minutes, the engine can return to high
speed if suction pressure is greater than 3 PSIG (0.2
bar) for 30 seconds or discharge pressure is less than
the calculated maximum for 30 seconds.
3. Engine Coolant Warm-Up.
The engine will run in low speed until the coolant is
above 79°F (26°C).
4. Defrost.
The engine Is generally in high speed but will run in low
speed during the high ambient pump down and at the
end of the defrost cycle while the refrigerant control
solenoids are realigned.
5. Door/Remote Switch Configuration.
If the DOOR/REMOTE SWITCH Configuration is set
for low speed, the engine will run in low speed when
the door/remote switch is open/active.