BAS-SVX48H-EN
59
Table 12. Diagnostic Causes and Diagnostics (continued)
Probable Cause
Diagnostic
Failed End Device
Check damper actuator to ensure proper operation.
No Power to the
Controller
If the UC400 Controller does not have power, the outdoor air damper does not operate. For the
controller to operate normally, apply an input voltage of 24 Vac. If the Marquee/Power LED is OFF
continuously, the controller does not have sufficient power or has failed.
Diagnostic Present Several diagnostics affect outdoor air damper operation.
Normal Operation
The UC400 Controller opens and closes the outdoor air damper based on the occupancy mode of
the controller and the fan status. Normally, the outdoor air damper is open during occupied mode
when the fan is running and closed during unoccupied mode.
Unit Configuration
The UC400 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.
Warm-up and Cool-down
Sequence
The UC400 Controller includes both a morning warm-up and cool-down 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.
Requested Mode Off
The user can communicate a desired operating mode (such as OFF, heat, or cool) to the controller.
If OFF is communicated to the UC400 Controller, the controller closes the outdoor air damper.
Outdoor Air Damper Remains Open
Unit Wiring
The wiring between the UC400 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 UC400 Controller opens and closes the outdoor air damper based on the controller occupancy
mode and fan status. Normally, the outdoor air damper is open during occupied mode when the
fan is running and closed during unoccupied mode.
Unit Configuration
The UC400 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.
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