Document Part # 026-4703 Rev 8 10-JUN-2009
Page 15 of 18
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Installation Instructions: Control Link ACC Anti-Condensate Controller System
technical bulletin
simply changing it on the dewpoint sensor), and it also allows multiple cases to use the same sensor while using
different temperature offsets.
When setting up Control Link ACCs and temperature offset jumpers, choose either a HIGH offset (4 degrees C),
a MEDIUM offset (2 degrees C) or a LOW offset (0 degrees C) and set each Control Link ACC and the dewpoint
sensor to the required position for the chosen offset.
Step 8 - Replace the Control Link ACC Enclosure Covers and Restore Power
Network configuration is complete. Replace the enclosure cover by pressing it against the enclosure until it snaps
into place. Restore power to the Control Link ACC. Check the status of the network by observing the LEDs on
the front of each Control Link ACC enclosure:
•If network communication is active, you should see the Rx LEDs blinking about once every 15 seconds. If you see no activity or
a regular blinking pattern, there may be a problem with the MODBUS network wiring or configuration.
•For Control Link ACCs equipped with dewpoint sensors, you should see the Tx LED blink to indicate transmission. If not, there
may be a problem with MODBUS or dewpoint sensor wiring.
•For Control Link ACCs that do not have dewpoint sensors directly connected to them, verify the STATUS LED is blinking once
every 2 seconds to indicate status is OK. If this LED blinks in a repeating pattern of three short blinks, it means the Control
Link ACC is not receiving a dewpoint sensor value broadcast over the network. There may be a problem with the MODBUS
or dewpoint sensor wiring.
Operation
Control Link ACC Status LEDs
The Control Link ACC has four status LEDs that indicate what the controller is
doing. They are: the Heater Status LED (HEAT), the General Status LED (Status)
and the two Network Status LEDs (Tx and Rx).
Heater Status LED
The Heater Status LED (HEAT) glows red any time the door heaters are ON, and
is OFF when the heaters are OFF.
Under normal operation, this LED should pulse ON and OFF when no door sweat
is visible, indicating it is pulsing the heaters to maintain the necessary amount of
heat to prevent door sweating (given the current dewpoint and case temperature).
When a case door is opened, the LED will remain ON for longer periods of time
(and may even remain ON without pulsing) to compensate for the change in case
door temperature.
Note that it is possible for this LED to remain OFF for long periods of time if the dewpoint is very low (e.g., dur-
ing dry winter days).
TIP: Experiment with offsets to find the lowest possible setting that still offers good
performance. In many cases, depending on the placement of the door frame tempera-
ture sensor, a LOW offset will still provide good anti-condensate performance. The
lower the offset being used, the higher the energy savings.
Figure 22 - LED Locations
