Carrier TRANSICOLD VECTOR 8100 Operation & Service Manual Download

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TIP

Ice is not the only thing that will cause the air differential to increase across the evaporator coil. Shrink
wrap, paper, plastic bags, and other such items when caught in the return air stream and pulled up
against the evaporator coil or the return air grille can also cause the DAS contacts to close.

b. Defrost based on time:

Time interval between defrosts is selected in the Functional Parameters. The parameter value may be set to 1.5, 3,
6, or 12 hours. The factory default setting is 6 hours.

NOTE

The defrost timer will not count when the unit is in defrost, the unit is in a Start/Stop off cycle or the
DTT is greater than 40.0°F (4.4°C).

4.7.2

Defrost Modes

There are two Defrost Modes available:

Normal Defrost Mode will be entered if RAT is less than 32.0°F (0.0°C) and SAT is less than 45.0°F (7.2°C).
Defrost will be accomplished by shutting down the refrigeration system while the heaters (HTCON1 & HTCON2)
are energized.
Electric heaters will be used for all defrost with fans off when temperatures are less than 32°C (89.6°F) for RAT and
less than 45°C (113°F) for SAT. For defrost requests at temperatures higher (RAT > 35°C, SAT > 45°C, heaters will
not be energized.

Natural Defrost Mode uses a combination of heat from the product and the electric heaters to melt ice.

Natural defrost is available when:

• the Natural Defrost Configuration is set to YES

and

• defrost is initiated by closing of the DAS contacts with RAT greater than or equal to 39.2°F (4.0°C) and

• at least one normal defrost has been performed since power up and

• this initiation will not result in more than 3 natural defrosts between normal defrosts

When a natural defrost is initiated, the unit will operate for the first five minutes with the evaporator fan and
HTCON2 de-energized, and only HTCON1 energized. After 5 minutes the evaporator fan is energized while both
HTCON1 & HTCON2 are de-energized.

4.7.3

Defrost Termination

When in defrost mode, defrost will terminate when the DTT rises to 55°F (12.8°C).

When operating in Natural Defrost mode, defrost will continue for a minimum of 5 minutes, a maximum of 10 min-
utes, or until the SAT is equal to or higher than RAT.

During Defrost Termination the heaters will de-energize.

The EVXV will open, and the evaporator coil will begin to cool down. The evaporator fans will not come on right
away, so that warm air is not blown into the refrigerated compartment, but will wait for the evaporator to cool down,
up to a maximum of 8 minutes.

If there is a DTT sensor alarm present, defrost will terminate after 10 minutes.

NOTE

Defrost Mode uses a Defrost Duration Timer that allows for a maximum of 45 minutes in defrost. If
defrost is not terminated during the 45 minutes, the control system will end the defrost cycle, and show
the alarm “DEFROST NOT COMPLETE”. When this occurs, the Defrost Interval Timer is set for 1.5
hours, at which time the unit will go into defrost again.