Troubleshooting
CNT-SVX05B-EN 95
Table 66. Valves stay closed
Probable cause Explanation
Requested mode Off You can communicate a desired operating mode (such as Off, Heat, and Cool) to the
controller. When Off is communicated to the controller, the unit controls the fan Off.
There is no heating or cooling (valves are closed).
Power-up control wait When power-up control wait is enabled (non-zero time), the controller remains Off
until one of two conditions occurs:
The controller exits power-up control wait when it receives communicated
information.
The controller exits power-up control wait when the power-up control wait time
expires.
Manual output test The controller includes a manual output test sequence you can use to verify output
operation and associated output wiring. However, based on the current step in the
test sequence, the valve(s) may not be open. Refer to “Performing a manual output
test” on page 84.
Fan mode Off When a local fan mode switch (provided on the Trane zone sensor) determines the fan
operation, the Off position controls the unit Off and closes the valves.
Diagnostic present Specific diagnostics affect valve operation. For more information, see Table 63 on
page 91.
No power to the
controller
If the controller does not have power, a normally open valve remains closed. For the
controller or valve to operate normally, it must have an input voltage of 24 Vac. When
the green LED is Off continuously, the controller does not have sufficient power or
has failed.
No power to the valves If the valve does not have power, a normally open valve remains closed. The valves
are powered separately from the controller's output signal. If the valves do not have
24 Vac, the controller cannot operate the valves.
Unit configuration The controller must be properly configured based on the actual installed end devices
and application. When the unit configuration does not match the actual end devices,
the valves may not work correctly.
Unit wiring The wiring between the controller outputs and the valve(s) must be present and cor-
rect for normal valve operation.
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