Tracer UC 400 Controller
146 UNT-SVX07E-EN
Troubleshooting UC400 Controller
Fans
Generic AIP failure
Invalid or missing value for generic
analog input.
•Fan Unaffected
•Valves Unaffected
• Outdoor air damper Unaffected
• DX cooling/electric heat Unaffected
Informational
Local fan mode failure
Invalid or missing fan-speed switch
(reverts to default fan speed).
•Fan Unaffected
•Valves Unaffected
• Outdoor air damper Unaffected
• DX cooling/electric heat Unaffected
Automatic
Local setpoint failure
Invalid or missing value for zone
temperature setpoint (reverts to default
setpoint).
•Fan Unaffected
•Valves Unaffected
• Outdoor air damper Unaffected
• DX cooling/electric heat Unaffected
Automatic
Note:
1
For detailed information about zone temperature control methods, refer to “Zone Temperature Control,” page 115
Table 87. Diagnostics generated by UC4000 controller
Diagnostic Probable Cause Consequences Diagnostic Type
Table 88. Fan does not energize
Probable Cause Explanation
Unit wiring
The wiring between the controller outputs and the fan relays and contacts must be present and correct for normal
fan operation. Refer to applicable wiring diagram.
Failed end device The fan motor and relay must be checked to ensure proper operation.
Normal operation
The fan will turn OFF when:
• The controller receives a communicated off signal
• The fan-speed switch is set to OFF if no communicated value is present
• Specific diagnostics are generated
• The default fan speed is set to OFF and the fan is operating in the Auto mode.
If the controller is in unoccupied mode, the fan cycles between OFF and the highest fan speed.
No power to
the controller
If the controller does not have power, the unit fan does not operate. For the controller to operate normally, it must
have 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 fan operation. For detailed information about these diagnostics, refer to Table 87,
page 145.
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 fans may not work correctly.
Random start observed
After power-up, the controller always observes a random start from 5 to 30 seconds. The controller remains OFF
until the random start time expires.
Cycling fan operation/
continuous
The controller continuously operates the fan when in the occupied, occupied standby, or occupied bypass mode.
When the controller is in the unoccupied mode, the fan is cycled between high speed and OFF with capacity.
Unoccupied operation
Even if the controller is configured for continuous fan operation, the fan normally cycles with capacity during
unoccupied mode. While unoccupied, the fan cycles ON or OFF with heating/cooling to provide varying amounts
of heating or cooling to the space.
Fan mode off If a local fan mode switch determines the fan operation, the OFF position controls the fan to off.
Requested mode off
The user can communicate a desired operating mode (such as OFF, heat, and cool) to the controller. If OFF is
communicated to the controller, the unit controls the fan to off. There is no heating or cooling.
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