Trane UniTrane User Manual

Diagnostics and Troubleshooting
148 UNT-SVX07J-EN
Table 89. Valves remain open
Probable Cause Explanation
Unit wiring
The wiring between the controller outputs and the valve(s) must be present and correct for normal valve operation.
Refer to applicable wiring diagram.
Failed end device The valves must be checked to ensure proper operations.
Normal operation The controller opens and closes the valves to meet the unit capacity requirements.
Diagnostic present
Several diagnostics affect valve operation. For detailed information about these diagnostics, refer to Table 86,
p. 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 valves may not work correctly.
Entering water temperature
sampling logic
The controller includes entering water temperature sampling logic, which is automatically initiated during 2-pipe
and 4-pipe changeover, if the entering water temperature is either too cool or too hot for the desired heating or
cooling.
Valve configuration
Ensure the valves are correctly configured, using the Tracer
®
TU service tool, as normally open (NO) or normally
closed (NC) as dictated by the application. For modulating valves, ensure the stroke time is set correctly. Refer
to Tab l e 2 3 , p. 5 8 .
Freeze avoidance
When the fan is OFF with no demand for capacity (0%), and the outdoor air temperature is below the freeze
avoidance setpoint, the 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 the fan is OFF.
DX Coils or Electric Heat with UC400-B Controller
Table 90. DX or electric heat does not energize
Probable Cause Explanation
Unit wiring
The wiring between the controller outputs and the end devices must be present and correct for normal operation.
Refer to applicable wiring diagram.
Failed end device
Check the control contactors or the electric heat element, including any auxiliary safety interlocks, to ensure proper
operation.
No power to the controller
If the 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 continuously, the controller does not have sufficient
power or has failed.
Diagnostic present
Several diagnostics affect DX and electric heat operation. For detailed information about these diagnostics, refer
to Table 86, p. 145.
Normal operation The controller controls compressor or electric heat outputs as needed to meet the unit capacity requirements.
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, DX or electric heat may not operate correctly.
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 shuts off the compressor or electric heat.
Freeze avoidance
When the fan is OFF with no demand for capacity (0%), and the outdoor air temperature is below the freeze
avoidance setpoint, the 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.

Trane UniTrane Specifications

General

Brand	Trane
Model	UniTrane
Category	Heater
Language	English