Carrier TRANSICOLD 69NT20-274 Operation And Service page 24

de-energized to allow the system to recover. The
out-of-range timer starts as soon as the temperature
exceeds the in-range tolerance value set by code Cd29.
Cooling capacity reduction by modulation is the
same as described for the conventional operating mode
when any of the above 4 conditions are invalid.
With set points below ---10_C (+14_F), operation is
the same as previously described for conventional mode
--- heating and dehumidification are locked out.
b. Frozen range below --- 10_C (+14_F)
The return air probe is used for control and is so
indicated by the LED on the display board.
The Frozen temperature range is not sensitive to
minor temperature changes. The method of temperature
control employed in this range takes advantage of this
fact, to greatly improve the energy efficiency of the
system. Temperature control in the Frozen range below
---10_C (+14_F) is accomplished by cycling the
compressor on and off as the load demand requires.
If the return air temperature in the container drops
0.2_C (0.4_F) below the set point temperature, the
compressor is cycled off. When the temperature is
greater than 0.2_C (0.4_F) above set point and 6 minute
time delay has been met, the compressor will restart. The
system will always operate at full capacity which means
both the solenoid modulating (SMV) and suction
solenoid (SSV) valves are fully open unless suction
solenoid override is activated. See section 1.11 for
explanation of suction solenoid override.
The temperature control is still within the tight
limits. Conditions could exist, however, which may cause
the return air temperature to rise rapidly. Such a case
would be the initial reaching of set point temperature.
When the set point temperature is initially reached, the
load may still be warmer than the set point temperature.
This could cause a rapid rise in return air temperature
when the compressor is off, causing a rapid restart or
on/off cycling of the compressor which is undesirable. To
prevent this from occurring, a 6 minute compressor off
time must be satisfied before the compressor will restart.
Under a condition of a rapidly changing return air
temperature, the time delay may allow the return air
temperature to rise slightly more than 0.2_C (0.4_F)
above the set point temperature before the compressor
can restart.
1.13.4 Function and Data Codes
There are 30 functions which the operator may
access to examine the operating status of the unit. To
access these functions, perform the following: Press the
code select key, press an arrow key until the left window
displays the desired code number (see Table 1-4). The
right window will display the value of this item for 5
seconds before returning to the normal display mode. If a
longer time is desired, pressing the Enter key will extend
the time to 30 seconds after the last pressing of the Enter
key. Below is an explanation of all Function codes.
Revised 8-6-93
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Table 1-4. Function Code Assignments
FUNCTION
CODE DATA
Display Only Functions
Cd00 Alarm List
Cd01 Suction Modulation Valve Opening (%)
Quench Valve (Open --- Closed)
DCd02
Cd03 Suction Solenoid Valve (Open --- Closed)
Cd04 Line Current, Phase A
Cd05 Line Current, Phase B
Cd06 Line Current, Phase C
Cd07 Supply Voltage
Cd08 Supply Frequency
Cd09 Ambient Air Temperature
Cd10 Compressor Suction Temperature
Compressor Discharge Temperature
DCd11
Saturated Condenser Temperature
DCd12
Compressor Discharge Pressure
DCd13
Cd14 Future Expansion
Cd15 Future Expansion
Cd16 Compressor Motor Hour Meter
Hours Since Last Trip Start
DCd17
Cd18 Software Revision Number
Serial # (First 4 of 8)
DCd19
Serial # (Second 4 of 8)
DCd20
USDA #1 Probe Temperature
DCd21
USDA #2 Probe Temperature
DCd22
Secondary Return Air Temperature
DCd23
(USDA)
Cd24 Secondary Supply Air Temperature
Cd25 Time Remaining Until Defrost
Display/Select Functions
Cd26 Defrost Interval
Cd27 Temperature Units (_C or _F)
Cd28 Failure Action
Cd29 In-Range Tolerance
Cd30 Stagger Start Offset Time
Cd31 Current Limit
Cd32 Dehumidification Control (Optional)
D = Codes that are NOT APPLICABLE for some units
Code 00 --- Alarm List Display Selection
(See Table 1-3 and Table 1-4)
This process will allow the user to examine all alarms
that are written in the list. To notify the user of the top of
the list, "Strt" is displayed. By using the arrow keys, the
entire list may be displayed. Each alarm number will be
preceded by a status indication, "IA" for inactive alarm
and "AA" for active alarm. See Alarm section.
Code 01 --- Suction Modulation Valve Opening (%)
The suction modulation valve (SMV) is a normally
open valve which restricts flow of refrigerant to the
compressor when energized by a pulse width modulated
(PWM) output. The amount of closing of the valve is
proportional to the applied current over the range of 0.2
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