Wired Zone Sensor Failure - Trane Tracer Uc

Troubleshooting
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Wired Zone Sensor Failure

Hazardous Service Procedures!
The maintenance and troubleshooting procedures recommended in this section of the manual
could result in exposure to electrical, mechanical or other potential safety hazards. Always
refer to the safety warnings provided throughout this manual concerning these procedures.
When possible, disconnect all electrical power including remote disconnect and discharge all
energy storing devices such as capacitors before servicing. Follow proper lockout/tagout
procedures to ensure the power can not be inadvertently energized. When necessary to work
with live electrical components, have a qualified licensed electrician or other individual who
has been trained in handling live electrical components perform these tasks. Failure to follow
all of the recommended safety warnings provided, could result in death or serious injury.
In the event that the UC400 controller reports an incorrect zone temperature, check the following:
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62
– Connect the shield portion of the wire at the first unit controller in the link.
– Tape back the shield at the end of the unit controller line.
– Wire together and tape all other shields at each unit controller.
Check application version and build or download the latest application version using the Tracer
TU service tool.
Note: For instructions on how to use Tracer TU, refer to the Tracer TU online Help and the
Tracer TU Service Tool Getting Started Guide (TTU-SVN02).
If communication loss persists, we recommend connecting to the link with Serial Spy MS/TP
analyzer to review the token passing. For detailed instructions about use, analysis and Comm
link voltage tests, refer to the BACnet MS-TP Wiring and Link Performance Best Practices and
Troubleshooting Guide (BAS-SVX51).
Verify that the actual room temperature is higher or lower than what the UC400 controller reads.
Check the location and installation of the zone sensor for heat sources or drafts. If necessary,
a calibration offset can be added with Tracer TU, in the Space Temperature Local configuration
screen.
Note: If the zone sensor is OFF more than ± 2 degrees, proceed to the next bullet item.
Verify that the zone sensor is wired correctly. Refer to the section,
Verify that the zone sensor is working properly.
– Disconnect the zone sensor terminal plug from the UC400 controller and using an
ohmmeter, measure the resistance across the terminals 1 and 2. Compare the resistance to
the temperature (refer to
near those measured with an accurate temperature measuring device. If not, replace the
zone sensor.
Verify that neither the wiring or the UC400 controller are defective. With wires still connected
to the UC400 controller, disconnect zone sensor wires that were connected to terminals 1 and
2 of zone sensor. Measure for 2.6–3.0 Vdc and if it is not present, then verify whether the UC400
controller is outputting 2.6–3.0 Vdc.
To do this, disconnect the wires on the UC400 controller from terminals AI1 and
measure the Vdc– it should be 2.6–3.0 Vdc. If 2.6–3.0 Vdc is present at the UC400 controller, the
wires going to the zone are OPEN. If the correct voltage is not present, check the incoming
power to the UC400 controller on XFMR 24 Vac input and
If the proper voltage is measured at the XFMR 24 Vac input and
AI1 and , replace the UC400 controller.
WARNING
Table 11, p. 63). The resistance value should be within ± 2 degrees
"Wiring Installation, " p.
, and
. It should measure 24 Vac ± 15%.
, and there is no voltage at
VAV-SVX07B-EN
13.