Trane UniTrane User Manual

Diagnostics and Troubleshooting
UNT-SVX07J-EN 147
Fans with UC400-B Controller
Table 87. 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 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 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 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.
Valves with UC400-B Controller
Table 88. Valves remain closed
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 operation.
No power to the controller
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.
Diagnostic present
Several diagnostics affect valve operation. For detailed information about these diagnostics, refer to Table 86,
p. 145.
Normal operation The controller opens and closes the valves 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, the valves 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.
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.
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 or normally closed
as dictated by the application. For modulating valves, ensure the stroke time is set correctly. Refer to Table 23,
p. 58.

Trane UniTrane Specifications

General

Brand	Trane
Model	UniTrane
Category	Heater
Language	English