Carrier 69NT40-561-300, Operation And Service Manual

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T-365 4–8
At the start of each cooling or heating cycle, the evaporator fans will run in high speed for three minutes. They will
then be switched to low speed any time the supply air temperature is /- 0.2°C (0.36°F) of the set point and
the return air temperature is less than or equal to the supply air tempe3°C (5.4°F). The fans will continue to
run in low speed for one hour. At the end of the hour, the evaporator fans will switch back to high speed and the
cycle will be repeated. If bulb mode is active, economy fan mode will be overridden.
4.3.11 Perishable Mode Cooling - Sequence of Operation
NOTICE
In Standard Perishable Mode, the evaporator motors run in high speed. In Economy Fan Mode,
the fan speed is varied.
a. When supply air temperature is above set point and decreasing, the unit will cool with the condenser fan
motor (CF and FS), compressor motor (CH), evaporator fan motors (EF) energized, and the white COOL
light illuminated. (See
Figure 4.6 ).
Figure 4.6 Perishable Mode Cooling
b. When supply air temperature decreases to a predetermined tolerance above set point (Cd30), the green IN
RANGE light is illuminated.
c. Condenser fan speed will change dependent on the following conditions:
Change high speed to low speed (LC):
Compressor loading ratio falls below 38%
Change low speed to high speed:
Compressor loading ratio above 45%
If compressor discharge pressure is above 200psig and condenser fan speed is high speed, then it will ratio.
d. The controller continuously monitors supply air temperature. Once the supply air temperature falls below set
point, the controller periodically records supply air temperature, set point and time. A calculation is then per-
formed to determine temperature drift from set point over time. If the calculation determines that cooling is
no longer required, contacts TC and TN are opened to de-energize the compressor motor and the con-
denser fan motor. In addition the controller will close the EEV.
e. The evaporator fan motors continue to run to circulate air throughout the container. The green IN RANGE
light remains illuminated as long as the supply air temperature is within tolerance of the set point.
ENERGIZED
DE-ENERGIZED
24 VOLT POWER
ST
F
HPS
CH
IP-CM
TC
CF
TE
IP-EM1
EF
IP-EM2
HTT
TH
HR
ESV
TS
TV EF ES
TN
FS
LC
TG
CF FS
LC
TG