Trane Tracer ZN.520 Installation Owner Diagnostics page 62

Valves
Table 30: Valves stay closed
Probable cause
Unit wiring
Random-start observed
Unit configuration
Power-up control
wait
Diagnostic present
Manual output test
Fan mode off
Requested mode off
Sampling logic
Table 31: Valves stay open
Probable cause
Unit wiring
Unit configuration
Diagnostic present
Manual output test
Sampling logic
UV-SVP01A-EN
Troubleshooting
The wiring between the controller outputs and the valve(s) must be present and correct for normal
valve operation.
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 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.
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 once it receives communicated information.
The controller exits power-up control wait once the power-up control wait time expires.
A specific list of diagnostic affects valve operation. For more information see, Tracer™ ZN.520 Unit
Controller diagnostics, on page 52 for more information.)
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. For more information see, Manual Output Test, on page 48 for more information.)
When a local fan mode switch (provided on the Trane zone sensor) determines the fan operation, the
off position controls the unit off and valves to close.
You can communicate a desired operating mode (such as
is communicated to the controller, the unit controls the fan
OFF
(valves are closed).
The controller includes entering water temperature sampling logic which is automatically invoked
during 2-pipe and 4-pipe changeover when the entering water temperature is either too cool or too hot
for the desired heating or cooling. For more information see, Entering Water Temperature Sampling,
on page 43 for more information.)
Example: A 2-pipe heat/cool changeover unit will not cool if the entering water temperature is too
warm for cooling or if the entering water sensor is not present. The unit will not heat if the entering
water temperature is too cool for heating. If failed the controller will close valve for one hour then
reattempt sampling routine.
The wiring between the controller outputs and the valve(s) must be present and correct for normal
valve operation.
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.
A specific list of diagnostic affects valve operation. For more information see, Tracer™ ZN.520 Unit
Controller diagnostics, on page 52 for more information.)
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 be
open.For more information see, Manual Output Test, on page 48 for more information.)
The controller includes entering water temperature sampling logic which automatically invoked during
2-pipe and 4-pipe changeover when the entering water temperature is either too cool or too hot for the
desired heating or cooling. For more information see, Entering Water Temperature Sampling, on page
43 for more information.)
Possible Explanation
, , and
OFF HEAT
. There is no heating or cooling
OFF
Possible Explanation
) to the controller. When
COOL
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