Trane Tracer UC400 Installation, Operation And Maintenance Manual page 58

O O p p e e r r a a t t i i o o n n a a l l C C a a u u s s e e s s a a n n d d D D i i a a g g n n o o s s t t i i c c s s
Table 12. Diagnostic Causes and Diagnostics (continued)
Diagnostic
Probable Cause
The user can communicate a desired operating mode (such as OFF, heat, and cool) to the
controller. If OFF is communicated to the UC400 Unit, it controls the fan to off. There is no heating
Requested Mode Off or cooling.
Entering Water The UC400 Controller includes entering water temperature sampling logic It is automatically
Temperature Sampling initiated during 2-pipe and 4-pipe changeover if the entering water temperature is either too cool
Logic or too hot for the desired heating or cooling.
Ensure the valves are correctly configured, using the Tracer TU service tool, as normally open
Valve Configuration (NO) or normally closed (NC) as dictated by the application.
Isolation Valves Remain Open
The wiring between the UC400 Controller outputs and the valve(s) must be present and correct
Unit wiring for normal valve operation. Refer to applicable wiring diagram.
The valves must be checked to ensure proper operations.
Failed End Device
Normal Operation The UC400 Controller opens and closes the valves to meet the unit capacity requirements.
Diagnostic Present Several diagnostics affect valve operation.
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 valves may not
Unit Configuration work correctly.
Entering Water The UC400 Controller includes entering water temperature sampling logic. It is automatically
Temperature Sampling initiated during 2-pipe and 4-pipe changeover if the entering water temperature is either too cool
Logic or too hot for the desired heating or cooling.
Ensure the valves are correctly configured, using the Tracer TU service tool, as normally open
Valve Configuration (NO) or normally closed (NC) as dictated by the application.
When the fan is OFF with no demand for capacity (0%), and the outdoor air temperature is below
the freeze avoidance setpoint, the UC400 Controller opens the water valves (100%) to prevent
coil freezing. This includes unoccupied mode when there is no call for capacity or any other time
Freeze Avoidance the fan is OFF.
DX or Electric Heat Outputs Do Not Energize
The wiring between the UC400 Controller outputs and the end devices must be present and
Unit Wiring correct for normal operation.
Check the UC400 Controller contactors or the electric heat element, including any auxiliary safety
interlocks, to ensure proper operation.
Failed End Device
If the UC400 Controller does not have power, heat outputs do not operate. For the controller to
operate normally, apply an input voltage of 24 Vac. If the Marquee/Power LED is OFF
No Power to the
continuously, the controller does not have sufficient power or has failed.
Controller
Diagnostic Present Several diagnostics affect DX and electric heat operation.
The UC400 Controller controls compressor or electric heat outputs as needed to meet the unit
Normal Operation capacity requirements.
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, DX or electric heat
Unit Configuration may not operate correctly.
The user can communicate a desired operating mode (such as OFF, heat, and cool) to the
controller. If OFF is communicated to the UC400 Controller, the controller shuts off the
Requested Mode Off compressor or electric heat.
When the fan is OFF with no demand for capacity (0%), and the outdoor air temperature is below
the freeze avoidance setpoint, the UC400 Controller disables compressors and electric heat
outputs (100%) to prevent coil freezing. This includes unoccupied mode when there is no call for
capacity or any other time the fan is OFF.
Freeze Avoidance
Outdoor Air Damper Remains Closed
The wiring between the UC400 Controller outputs and the outdoor air damper must be present
Unit Wiring and correct for normal outdoor air damper operation. Refer to applicable wiring diagram.
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