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T-318
3
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22
Table 3-5 Controller Function Codes (Sheet 3 of 9)
Code
No.
TITLE
DESCRIPTION
Configurable Functions
Configurable Functions
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Cd27 through Cd37 are user-selectable functions. The operator can change the value of
these functions to meet the operational needs of the container.
Cd27 Defrost Interval
(Hours or Automatic)
There are two modes for defrost initiation, either user-selected timed intervals or
automatic control. The user-selected values are (OFF), 3, 6, 9, 12, 24 hours,
AUTO, or PuLS. Factory default is 3 hours.
Automatic defrost starts with an initial defrost at three hours and then adjusts the
interval to the next defrost based on the accumulation of ice on the evaporator
coil. Following a start-up or after termination of a defrost, the time will not begin
counting down until the defrost temperature sensor (DTS) reading falls below set
point. If the reading of DTS rises above set point any time during the timer count
down, the interval is reset and the countdown begins over.
If the DTS fails, alarm code AL60 is activated and control switches over to the
return temperature sensor. The controller will act in the same manner as with the
DTS except the return temperature sensor reading will be used.
If CnF23 is configured to “SAv” (save), then the value of the defrost interval timer
will be saved at power down and restored at power up. This option prevents short
power interruptions from resetting an almost expired defrost interval, and possibly
delaying a needed defrost cycle.
NOTE
The defrost interval timer counts only during compressor run time.
Configuration variable (CnF11) determines whether the operator will be allowed to
chose “OFF” as a defrost interval option.
Configuration variable (CnF64) determines whether the operator will be allowed to
choose “PuLS” as a defrost interval option. For units operating with “PuLS” se-
lected, defrost interval is determined by the unit temperature setpoint and the
Evaporator Fan Pulsing Temperature Setting (Cd60). When the unit temperature
setpoint is equal to or less than the Evaporator Fan Pulsing Temperature Setting,
the defrost interval is set to 6 hours. Otherwise, the defrost interval is determined
using the Automatic Defrost Interval Determination logic. In either case, “PuLS”
remains displayed in this function select code.
After a new Defrost Interval is selected, the previously selected Interval is used
until the next defrost termination, the next time the DTT contacts are OPEN, or
the next time power to the control is interrupted. If the previous value or the new
value is “OFF”, the newly selected value will be used immediately.
If any Auto Pretrip sequence is initiated, Cd27 will be set to ’AUTO’ unless CnF49
(OEM Reset) is set to “Custom” AND CnF64 (Evaporator Fan Pulsing Logic) con-
figuration variable is set to IN, in which case Cd27 will be set to “PuLS”.
Cd28
Temperature Units
(Degrees C or
Degrees F)
This code determines the temperature units (
°
C or
°
F) which will be used for all
temperature displays. The user selects
°
C or
°
F by selecting function code Cd28
and pushing the ENTER key. The factory default value is Celsius units. This
function code will display “
-----“ if
CnF34 is set to
°
F.
Cd29 Failure Action Mode
This is the desired action to be taken if an alarm occurs that severely limits the
capability of the control system. Depending upon what alarm has occurred, the
actual action taken may not be the same as the desired failure action.
The user selects one of four possible actions as follows:
A
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Full Cooling (stepper motor SMV at maximum allowed opening)
B
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Partial Cooling (stepper motor SMV 11% open)
C
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Evaporator Fan Only
D
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Full System Shutdown
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Factory Default