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4.7 AutoFresh Air Exchange
AutoFresh Air Exchange is a factory installed option that allows control of the atmospheric conditions within the
refrigerated compartment. When air is being exchanged, two air ports are opened. The upper port allows fresh
ambient air to enter while stale air exits through the lower port. Air Exchange is allowed with setpoints above 28°F
(-2.2°C). It is always closed when in defrost or in a Start-Stop OFF cycle regardless of Configuration or Functional
Parameter settings.
Operation is dependent on two Configurations and one or two Functional Parameters. When AutoFresh Air is
installed at the factory, the AUTO FRESH AIR configuration is set to INSTALLED. The control point at which it
becomes active is set in the control system configurations. The AUTO FRESH AIR DELAY Configuration may be
set to SETPOINT or a time value of 0 to 48 hours. If set to SETPOINT, control will begin when the control tempera-
ture is 1.5°F (0.8°C) away from setpoint. If a time value is entered, it will become active after the time has expired
and the system is no longer in Pulldown or Pull-up even if the control temperature has not reached 1.5°F (0.8°C)
away from setpoint.
The first parameter is the AUTOFRESH AIR Functional Parameter. It may be set to CLOSED, OPEN or CFM CON-
TROL. When set to CLOSED, AutoFresh Air is not operational. When set to OPEN, the ports will always be open
with setpoints above 28°F (-2.2°C).
When set to CFM CONTROL the AUTOFRESH AIR CONTROL Functional Parameter becomes available. The
Parameter may be set form 5 to 50 CFM in 5 CFM increments. Under CFM CONTROL, AutoFresh Air will operate on
a 20 minute cycle. During the cycle the ports will open until the required CFM has been exchanged and then close for
the remainder of the cycle.
Control Temperature with Fuel Saver OFF
HTCON1
Switch On when CT- SP is
less than -0.54°F (-0.3°C)
Switch Off when CT-
SP is greater than
-0.36°F (-0.2°C)
HTCON2
Switch On when CT- SP is
less than -3.6°F (-2.0°C)
Switch Off when CT-
SP is greater than
-3.24°F (-1.8°C)
Control Temperature with Fuel Saver ON
HTCON1
Switch On when CT- SP is
less than -1.44°F (-0.8°C)
Switch Off when CT-
SP is greater than
-1.26°F (-0.7°C)
HTCON2
Switch On when CT- SP is
less than -3.6°F (-2.0°C)
Switch Off when CT-
SP is greater than
-3.24°F (-1.8°C)
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