Carrier 69NT40-541-306, Операция и обслуживание

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5–11 T-354
5.10.3 Sequence of Operation - Frozen Mode Cooling
NOTE
In the Frozen Mode of operation the evaporator motors run in low speed.
NOTE
In low temperature ambients, the condenser fan will be cycled by the controller to maintain proper con-
densing pressure.
1. With supply air temperature above set point and decreasing, the unit will be cooling with the condenser fan
motor (CF), compressor motor (CH), evaporator fan motors (ES) energized and the COOL light illuminated
(see
Figure 5.7 ).
2. When the air temperature decreases to a predetermined tolerance above set point, the in-range light is illu-
minated.
Figure 5.7 Frozen Mode
3. Contacts TC and TN are opened to de-energize the compressor and condenser fan motors when the re turn
air temperature decreases to 0.2

C (0.4

F) be low set point. The cool light is also de-energized.
4. The evaporator fan motors continue to run to circulate air throughout the container. The in-range light re
mains illuminated as long as the return air is within tolerance of set point.
5. When the return air temperature increases to 0.2

C (0.4

F) above set point and the three minute off time has
elapsed, relays TC and TN are energized to restart the compressor and condenser fan motors. The cool
light is also illuminated.
CONTROL TRANSFORMER
POWER TO
CONTROLLER
SIGNAL TO
CONTROLLER
SIGNAL TO
CONTROLLER
ENERGIZED
DE-ENERGIZED
FOR FULL DIAGRAM AND
LEGEND, SEE SECTION 7