Tracer UC 400 Controller
UNT-SVX07E-EN 145
Manual (Latching) Diagnostics
Manual diagnostics (also referred to as latching) cause the
unit to shut down. Manual diagnostics can be cleared from
the UC400 controller in one of the following ways:
• By using the Tracer TU service tool to reset latching
diagnostics on the Alarms Status tab or by
temporarily overriding the Reset Diagnostic
Request (bv/2) on the Binary Status tab.
• Through a building automation system.
• By cycling power to the controller. When the 24Vac
power to the controller is cycled OFF and then ON
again, a power-up sequence occurs.
Automatic (Non-latching) Diagnostics
Automatic diagnostics clear automatically when the
problem that generated the diagnostic is solved.
Smart Reset Diagnostics
Smart Reset Diagnostics are latching diagnostics that will
auto-recover if the condition is corrected. After the
controller detects the first smart reset diagnostic, the unit
waits 30 minutes before initiating the smart reset function.
If another diagnostic of this type occurs again within
24 hours after an automatic clearing, clear the diagnostic
manually by using any of the ways listed under the
preceding section, “Manual (Latching) Diagnostics.”
Informational Diagnostics
Informational diagnostics provide information about the
status of the controller. They do not affect machine
operation, but can be cleared from the controller using the
BAS or Tracer SC.
Building Automation System
Some building automation systems can reset diagnostics
in the controller. For more complete information, refer to
the product literature for the building automation system.
Trane Service Tools
Tracer TU can be used to reset diagnostics present in a
Tracer UC400 controller.
Controller Diagnostics
Table 87 lists each diagnostic that can be generated by the
UC400 controller, the diagnostic effect on outputs
(consequences), and diagnostic type.
Note: The generic binary output is unaffected by
diagnostics.
Table 87. Diagnostics generated by UC4000 controller
Diagnostic Probable Cause Consequences Diagnostic Type
Filter change required
Fan run hours exceed the time set to
indicate filter change.
•Fan Unaffected
•Valves Unaffected
• Electric heat Unaffected
Informational
Condensate overflow The drain pan is full of water.
•Fan OFF
•Valves Closed
• Outdoor air damper Closed
• DX/electric heat OFF
Manual
Low coil temp detection
The leaving fluid temperature may be
close to freezing.
•Fan OFF
•Valves Open
• Outdoor air damper Closed
• DX/electric heat OFF
Smart reset/Manual
Low airflow supply fan
failure
The fan drive belt, contactor, or motor has
failed.
•Fan OFF
•Valves Closed
• Outdoor air damper Closed
• DX/electric heat OFF
Manual
Space temperature
failure
1
Invalid or missing value for zone
temperature.
• Discharge air temperature control runs
•Unit shuts OFF if both space temperature and
discharge air temperature fail
Automatic
Entering water temp
failure
Invalid or missing value for zone
temperature.
•Fan Unaffected (enabled)
•Valves Unaffected
• Outdoor air damper Unaffected
• DX/electric heat Unaffected
Automatic
Discharge air temp low
limit
Discharge air temperature has fallen
below the Discharge Air Temperature Low
Limit.
•Fan OFF
•Valves Open
• Outdoor air damper Closed
• DX/electric heat OFF
Smart reset/manual
Discharge air temp
failure
1
Invalid or missing value for discharge air
temperature.
• Simplified zone control algorithm runs
• Unit shuts OFF if zone temperature fails
Automatic
Outdoor air temp failure
Invalid or missing value for outdoor air
temperature.
•Fan Unaffected
•Valved Unaffected
• Outdoor air damper Minimum
Position
• DX cooling/electric heat unaffected
Automatic
Humidity input failure
Invalid or missing value for relative
humidity.
•Fan Unaffected
•Valves Unaffected
• Outdoor air damper Unaffected
• DX cooling/electric heat Unaffected
Automatic
CO
2
sensor failure Invalid or missing value for CO
2
.
•Fan Unaffected
•Valves Unaffected
• Outdoor air damper Unaffected
• DX cooling/electric heat Unaffected
Informational
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