Diagnosing operational problems
CNT-SVX12C-EN 91
Unit configuration The controller must be properly configured based on the actual installed end devices and
application. If the unit configuration does not match the actual end device, the outdoor air
damper may not work correctly.
No power to the
controller
If the controller does not have power, the outdoor air damper does not operate. For the
ZN517 controller to operate normally, you must apply an input voltage of 24 Vac. If the
green LED is off continuously, the controller does not have sufficient power or has failed.
Table 33. Outdoor air damper remains open
Probable cause Explanation
Unit wiring The wiring between the controller outputs and the outdoor air damper must be present
and correct for normal outdoor air damper operation. Refer to applicable wiring diagram.
Failed end device Check damper actuator to ensure proper operation.
Normal
operation
The controller opens and closes the outdoor air damper based on the controller’s occu-
pancy mode and fan status. Normally, the outdoor air damper is open during occupied
mode when the fan is running and closed during unoccupied mode.
Manual output test The controller includes a manual output test sequence you can use to verify output oper-
ation and associated output wiring. However, based on the current step in the test
sequence, the outdoor air damper may be open. Refer to the “Manual output test” on
page 74.
Unit
configuration
The controller must be properly configured based on the actual installed end devices and
application. If the unit configuration does not match the actual end device, the outdoor air
damper may not work correctly.
Table 32. Outdoor air damper remains closed (Continued)
Probable cause Explanation
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