62-12259 4–10
4.6.4.1 Pulldown
Pulldown will be entered:
• Following a Start-Up
• Following a Setpoint change (requiring additional cooling)
• Following an operational change (Start-Stop vs Continuous or Engine Operation vs Electric Operation)
• Following a defrost termination
OR
• When all other Stop Parameters have been met except the refrigerated compartment Temperature Stop
Parameter
Pulldown will end when one of the following occurs:
• When in Engine Operation and the control system is calling for low speed
• When in Start-Stop and the refrigerated compartment Temperature Stop Parameter has been satisfied while
one or more of the other Stop Parameters has not been satisfied
• If in Continuous Operation - perishable and the High Speed Pulldown Configuration is OFF and the tempera-
ture is in the required range. This range is calculated when Supply Temperature (ST) is equal to or less than
the Return Temperature (RT). The calculation is:
Off Value = (ST - RT)/2
When the Control Temperature is within a range of +/- the Off Value of set point, Pulldown mode ends.
• If in Continuous Operation - Perishable, and the High Speed Pulldown Configuration is ON: when the tem-
perature is equal to setpoint.
• When active probe is within the control temperature which allows the unit to shut off.
4.6.4.2 CSMV Control
CSMV Control will be entered when additional cooling is required and Pulldown is not allowed. In CSMV
Control the valve will be modulated so as to balance compressor capacity with the refrigeration load.
4.6.5 Heat Mode
When Heat mode is required the system will operate with the evaporator fans energized. Operation of the heaters
is determined in accordance with the calculated Controlling Temperature value (CT) and the difference between
this value and Setpoint (SP) in accordance with the following table.
HTCON1 may also be activated when the unit is in Continuous Operation Cooling to assist in balancing unit capacity
with the load. In all other operating states and modes HTCON1 and HTCON2 will not be activated.
4.6.6 Null Mode
for descriptions of operation in the Null mode, refer to Section 2.13 and Section 4.6.3.
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