Auto-Zone Control Systems Auto-Zone Plus Systems Installation & Operation (Version 03A) - Manual (Page 188)

Section 4 Auto-Zone Plus
4-38 Start-Up and Troubleshooting
3.0 Zone Controller
Overview
3.1 How It Works
3.1.1 Initialization
On system powerup the SCAN LED remains extinguished for five seconds. After this
delay, the SCAN LED will blink out the address of the controller (Address Switch
Setting). The SCAN LED will then extinguish for another five seconds and then begin to
blink for a twenty second startup delay. At the conclusion of this twenty second period,
the SCAN LED will begin blinking a diagnostic code every ten seconds. This code is
described later in this document. The duration of a powerup initialization sequence is
roughly one minute.
During this initialization period, the controller retrieves all operating setpoints from its
non-volatile EEPROM memory and initializes all outputs to an OFF condition. It also
tests to see if the optional relay expansion board is installed.
3.1.2 Calibration
During the powerup process, a self check of the zone damper actuator is performed. This
guarantees the damper is operating and also records the feedback range for use in
calculating 0 - 100 percent damper position readings. The damper is first driven to its
fully closed position. While the damper is fully closed, the controller checks for an
airflow sensor connected to the Airflow input. If it exists, the null voltage reading is
stored away for future use in airflow calculations. Next, the damper drives to its full open
position. At this point, it stores feedback values and remains open if no relay expansion
board is attached. If the relay expansion is attached, the damper drives to its fully closed
position. This is to protect series fan boxes from air in the main duct causing the series
fan to spin backwards before it can be powered up.
Note: If you change the zone damper operation from direct acting to reverse acting,
you must remove power from the zone and allow it to re-start and perform the
damper calibration in the new open/close directions.