T-372
4–4
4.3.2
Start Up - Compressor Bump Start
At start up, the controller logic will initiate a compressor bump start procedure to clear liquid refrigerant from the
compressor. If suction and discharge pressures have equalized, the compressor will perform three compressor
bump starts. A compressor bump start may also occur after a defrost cycle has been completed.
During bump start, the electronic expansion valve (EEV) will close. Relays TS, TN, TE, and TV will be de-ener
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gized (opened). The result of this action will close the economizer solenoid valve (ESV) and shut all fans off. The
compressor will start for 1 second, then pause for five seconds. This sequence will be repeated two more times.
After the final bump start, the unit will pre-position the EEV to the correct starting position, pause and then start up.
4.3.3
Perishable Mode (Temperature Control)
In Perishable Mode, the controller maintains the supply air temperature at setpoint, the SUPPLY indicator light is
illuminated and the default reading on the display window is the supply temperature sensor reading.
When the supply air temperature enters the in-range temperature tolerance (Cd30), the green IN-RANGE light will
energize.
When variable CnF26 (Heat Lockout Temperature) is set to -10°C, Perishable mode is active with setpoints above
-10°C (+14°F). When CnF26 is set to -5°C, Perishable mode is active with setpoints above -5°C (+23°F).
4.3.4
Perishable Pulldown Mode
In Perishable Pulldown Mode, the highest priority is given to bringing the container down to setpoint. When cooling
from a temperature that is more than 2.5°C (4.5°F) above setpoint, the system will be in Perishable Pulldown mode
in economized operation. However, pressure and current limit functions may restrict the valve if either exceeds the
preset value.
4.3.5
Perishable Steady State Mode
In Perishable Steady State Mode, the control temperature is maintained near a setpoint that is above the Heat
Lockout Temperature. Once setpoint is reached, the unit will transition to Perishable Steady State Mode. This
results in unloaded operation by cycling the digital unloader valve (DUV) to limit capacity and maintain steady tem
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perature control.
The unit is capable of maintaining supply air temperature to /- 0.2°C (+/- 0.36°F) of setpoint. Supply air tem
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perature is controlled by positioning of the electronic expansion valve (EEV), cycling of the DUV, cycling of the
compressor, and cycling of the heaters.
4.3.6
Perishable Idle Mode (Air Circulation)
When it is unnecessary to run the compressor to maintain control temperature, the system enters Perishable Idle
Mode. If the controller has determined that cooling is not required or the controller logic determines suction pres
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sure is at the low pressure limit, the unit will transition to Perishable Idle Mode. In this mode, the compressor is
turned off, but the evaporator fans continue to run to circulate air throughout the container. If temperature rises
+0.2°C (0.4°F) above setpoint, the unit will transition back to Perishable Steady State Mode.
4.3.7
Perishable Heating Mode
When it is necessary to raise the control temperature, the system will enter Perishable Heating Mode. If the tem
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perature drops to 0.5°C (0.9°F) below setpoint, the unit will transition to Perishable Heating Mode, and the heaters
will be energized. The unit will transition back to Perishable Idle Mode when the temperature rises to 0.2°C (0.4°F)
below the setpoint, and the heaters will de-energize.
