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4–7
T-359
4.3.7
Perishable Mode Cooling - Sequence of Operation
NOTE
In the Standard Perishable Mode of Operation, the evaporator motors run in high speed. In the Econ-
omy Perishable Mode, the fan speed is varied.
With supply air temperature above set point and decreasing, the unit will cool with the condenser fan motor (CF),
compressor motor (CH), evaporator fan motors (EF) energized and the COOL light illuminated. (See
Also, if current or pressure limiting is not active, the controller may close contacts TS to open the economizer sole-
noid valve (ESV) and place the unit in economized operation.
When the air temperature decreases to a predetermined tolerance above set point, the in-range light is illuminated.
4.3.8
Perishable Mode Heating - Sequence of Operation
a. If the air temperature decreases 0.5°C (0.9°F) below set point, the system enters the heating mode. (See
). The controller closes contacts TH (see
) to allow power flow through the heat termi-
nation thermostat (HTT) to energize the heaters (HR). The HEAT light is also illuminated. The evaporator
fans continue to run to circulate air throughout the container.
b. When the temperature rises to 0.2°C (0.4°F) below set point, contacts TH open to de-energize the heaters. The
HEAT light is also de-energized. The evaporator fans continue to run to circulate air throughout the container.
c. The safety heater termination thermostat (HTT) is attached to an evaporator coil circuit and will open the
heating circuit if overheating occurs.
4.3.9
Sequence of Operation - Perishable Mode (Capacity Trim Heat)
If the system capacity has been decreased to the lowest allowable capacity and conditions exist that warrant max-
imum temperature stability the controller will pulse the HR relay to energize the evaporator heaters in sequence
with the compressor digital signal. Trim heat is enabled only if (12.77°C < set point < 15.55°C [54.99°F < set point
< 59.99°F]) and (-6.67°C < ambient temperature < 1.66°C [19.99°F < ambient temperature < 34.99°F]).
Figure 4.6 Perishable Mode - Cooling
Figure 4.7 Perishable Mode Heating
NOTE
The EEV and DUV are independently operated by
the microprocessor. For full diagrams and legend,
see
.
NOTE
The EEV and DUV are independently operated
by the microprocessor. For full diagrams and
legend, see
24 VOLT POWER
ENERGIZED
DE--ENERGIZED
TN
ST
F
HPS
CH
IP--CM
TC
CF
TE
IP--EM1
EF
IP--EM2
HTT
TH
HR
ESV
TS
TV
EF
ES
24 VOLT POWER
ENERGIZED
DE--ENERGIZED
TN
ST
F
HPS
CH
IP--CM
TC
CF
TE
IP--EM1
EF
IP--EM2
HTT
TH
HR
ESV
TS
TV
EF
ES
Summary of Contents for 69NT40-561-019
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Page 128: ...T 359 8 4 Figure 8 3 UNIT WIRING DIAGRAM Evergreen Unit Configuration Sheet 1 of 2 ...
Page 129: ...8 5 T 359 Figure 8 4 UNIT WIRING DIAGRAM Evergreen Unit Configuration Sheet 2 of 2 ...
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