Carrier 69NT40-561-019, Operation And Service Manual

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4–5 T-359
To access the function codes, perform the following:
a. Press the CODE SELECT key, then press an arrow key until the left window displays the desired code number.
b. The right window will display the value of this item for five seconds before returning to the normal display mode.
c. If a longer time is desired, press the ENTER key to extend the time to five minutes.
4.3 CONTROLLER SEQUENCE AND MODES OF OPERATION
General operation sequences for cooling, heating, and defrost are provided in the following sub-paragraphs. Sche-
matic representation of controller action is provided in
Figure 4.5 .
The operational software responds to various inputs. These inputs come from the temperature and pressure sensors,
the temperature set point, the settings of the configuration variables and the function code assignments. The action
taken by the operational software will change if any one of the inputs change. Overall interaction of the inputs is
described as a “mode” of operation. The modes of operation include perishable (chill) mode and frozen mode.
Descriptions of the controller interaction and modes of operation are provided in the following sub paragraphs.
4.3.1 Start Up - Compressor Phase Sequence
The controller logic will check for proper phase sequencing and compressor rotation. If sequencing is allowing the
compressor and three-phase evaporator fan motor to rotate in the wrong direction, the controller will energize or
de-energize relay TCP as required (see
Figure 8.2 ). Relay TCP will switch its contacts, energizing or de-energizing
relays PA and PB. Relay PA is wired to energize the circuits(s) on L1, L2, and L3. Relay PB is wired to energize the
circuit(s) on L3, L2, and L1, thus providing reverse rotation.
4.3.2 Start Up - Compressor Bump Start
The controller logic will initiate a compressor bump start procedure to clear refrigerant from the compressor. If suc-
tion and discharge pressures have equalized, the compressor will perform three compressor bump starts. A com-
pressor bump start may occur after a defrost has been completed.
During the procedure, the EEV will close. Relays TS, TQ, TN, TE, TV will be de-energized (opened). The result of
this action will close the ESV and shut all fans off. The compressor will start for 1 second, then pause for five sec-
onds. This sequence will be repeated two additional times. After the final bump start the unit will pre-position the
EEV to correct starting position pause and startup.
4.3.3 Perishable Set Point Temperature - Perishable Pulldown
When cooling from a temperature that is more than 2.5°C (4.5°F) above set point, the system will be in the perish-
able pulldown mode in economized operation. However, pressure and current limit functions may restrict the valve
if either exceeds the preset value.
4.3.4 Perishable Set Point Temperature - Standard Temperature Control Mode
The unit is capable of maintaining supply air temperature to /-0.2°C (+/-0.36°F) of set point. Supply air tem-
perature is controlled by positioning of the electronic expansion valve (EEV), cycling of the digital unloader valve
(DUV), cycling of the compressor and cycling of the heaters.
Once set point is reached, the unit will transition to the perishable steady state mode. This results in unloaded
operation by cycling the DUV to limit capacity and maintain steady temperature control.
If the controller has determined that cooling is not required or the controller logic determines suction pressure is at
the low pressure limit, the unit will transition to the perishable idle mode. The compressor is turned off and the
evaporator fans continue to run to circulate air throughout the container. If temperature rises above set point
+0.2°C, the unit will transition back to the perish able steady state mode
If the temperature drops to 0.5°C (0.9°F) below set point, the unit will transition to the perishable heating mode and
the heaters will be energized. The unit will transition back to the perishable idle mode when the temperature rises
to 0.2°C (0.4°F) below the set point and the heaters will de-energize.
4.3.5 Perishable Set Point Temperature - Economy Fan Operation Mode
The economy mode is an extension of the standard mode. The mode is activated when the setting of function code
Cd34 is “ON”. Economy mode is provided for power saving purposes. Economy mode could be utilized in the
transportation of temperature-tolerant cargo or non-respiration items which do not require high air flow for removing
respiration heat. There is no active display indicator that economy mode has been activated. To check for economy
mode, perform a manual display of code Cd34.