Trane VUV Installation, Operation And Maintenance Manual page 112

Diagnostics and Troubleshooting
Fans with UC400-B/Symbio™ 400-B
Controller
Table 61. Fan does not energize
Probable Cause
Unit wiring
Failed end device
Normal operation
No power to
the controller
Diagnostic present
Unit configuration
Random start observed
Cycling fan operation/continuous
Unoccupied operation
Fan mode off
Requested mode off
Valves with UC400-B/Symbio™ 400-B
Controller
Table 62. Valves remain closed
Probable Cause
Unit wiring
Failed end device
No power to the controller
Diagnostic present
Normal operation
Unit configuration
Random start observed
Requested mode off
Entering water temperature
sampling logic
Valve configuration
Table 63. Valves remain open
Probable Cause
Unit wiring
Failed end device
Normal operation
Diagnostic present
Unit configuration
Entering water temperature
sampling logic
Valve configuration
Freeze avoidance
112
Explanation
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.
The fan motor and relay must be checked to ensure proper 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.
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.
Several diagnostics affect fan operation. For detailed information about these diagnostics, refer to
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.
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.
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.
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.
If a local fan mode switch determines the fan operation, the OFF position controls the fan to 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.
Explanation
The wiring between the controller outputs and the valve(s) must be present and correct for normal valve operation. Refer to
applicable wiring diagram.
The valves must be checked to ensure proper operation.
If the controller does not have power, the unit valve(s) will 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.
Several diagnostics affect valve operation. For detailed information about these diagnostics, refer to
The controller opens and closes the valves to meet the unit capacity requirements.
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.
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.
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.
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.
Ensure the valves are correctly configured, using the Tracer® TU service tool, as normally open or normally closed as dictated by
the application.
Explanation
The wiring between the controller Soutputs and the valve(s) must be present and correct for normal valve operation. Refer to
applicable wiring diagram.
The valves must be checked to ensure proper operations.
The controller opens and closes the valves to meet the unit capacity requirements.
Several diagnostics affect valve operation. For detailed information about these diagnostics, refer to
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.
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.
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.
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.
Table 60, p. 111.
Table 60, p. 111.
Table 60, p. 111.
UV-SVX005G-EN