Trane Tracer ZN.520 Manual page 101

CNT-SVX04A-EN
Troubleshooting
Table 65 Outdoor air damper stays closed
Probable cause Explanation
Unit wiring The wiring between the controller outputs and the outdoor air
damper must be present and correct for normal damper operation.
Unit configuration The controller must be properly configured based on the actual
installed end devices and application. When the unit configuration
does not match the actual end devices, the damper may not work
correctly.
Random start After power-up, the controller always observes a random start
observed from 5 to 30 seconds. The controller remains off until the random
start time expires.
Power-up control When power-up control wait is enabled (non-zero time), the
wait controller remains off until one of two conditions occurs:
The controller exits power-up control wait once it receives
communicated information.
The controller exits power-up control wait once the power-up
control wait time expires.
Diagnostic present A specific list of diagnostics affects outdoor air operation. For
more information, see Table on page 92.
Manual output test The controller includes a manual output test sequence you can
use to verify output operation and associated output wiring.
However, based on the current step in the test sequence, the unit
damper may not be open. Refer to "Manual output test" on
page 88.
Fan mode off When a local fan mode switch (provided on the Trane zone sensor)
determines the fan operation, the off position controls the unit off
and damper to close.
Requested mode off You can communicate a desired operating mode (such as off, heat,
and cool) to the controller. When off is communicated to the
controller, the unit controls the fan off. There is no heating or
cooling (valves are closed).
Freeze avoidance When the fan is off and the outdoor air temperature is below the
freeze avoidance setpoint, the controller disables economizing and
keeps the outdoor air damper closed. This includes unoccupied
mode when there is no call for capacity or any other time the fan is
off.
Unoccupied mode When the controller is in the unoccupied mode, the outdoor air
damper remains closed unless economizing is enabled.
Warm-up and The controller includes both a morning warm-up and cool-down
cool-down sequence sequence to keep the outdoor air damper closed during the
transition from unoccupied to occupied. This is an attempt to
bring the space under control as quickly as possible.
Normal operation The controller opens and closes the outdoor air damper based on
the controller's occupancy mode and fan operation. Normally, the
outdoor air damper is open during occupied, occupied standby,
and occupied bypass mode when the fan is running and closed
during unoccupied mode unless the controller is economizing.
Refer to "Modulating outdoor air damper operation" on page 66
for more information.
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