60 VAV-SVX07F-EN
Troubleshooting
VAV Damper Failure
WARNING
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 air valve does n
ot modul
ate, check the following:
• Tracer SC or Tracer TU service tool has enabled an override function in
the UC400. Verify no
overrides are present by clicking on the override icon of multi-state value 2, Air Flow Override,
on the TU Multi-state Status page.
– The overrides are Open, Closed, Min, or Max
. Release all over
rides.
– The UC400 controller is going through a recalibrate (reset) command. This is shown in the
diagnostic l
ist in Tracer TU service tool.
– Wait for calibration to finish.
• Zone temperature is greater than the heat setpoint o
r le
ss than the cool setpoint. Change the
heat and/or cool setpoint.
• Actuator not driving full drive ti
me.
– Drive time on TU Setup Parameters page, Stroke Times grou
p, not set at 90 seconds on
current Varitrane units.
– Adjust to correct damper travel tim
e using
Tracer TU service tool.
– Damper actuator loose on shaft.
– Tighten damper actuator set screw
to damper shaft by first rotating
damper fully clockwise
until closed, releasing actuator clutch and rotating actuator collar fully clockwise, and then
tightening the setscrews. Incorrect adjustment can result in broken stub axle adapters.
– Measure the power input to XFMR 24 Vac input and
on the UC400 controller. The supply
voltage should be between 20.4 to 27.6 Vac (24 Vac nominal). H
owever, voltages at either
extreme may result in system instability and cause damper to not be driven its full range.
– If no voltage, check up stream of controller to see were voltag
e has been interrupted. Refer
to the section, “Appendix: Typical Trane Factory Wiring Diagrams,” p. 68.
• Actuator motor has failed.
– Check voltage at the TRIAC supply B
to common
, which should be 24 Vac. If 24 Vac is not
present, check the incoming
power to the UC400 controller on XFMR 24 Vac input and
TRIAC supply. The voltage should measure 24 Vac, ± 15%. After measuring for the proper
voltage at XFMR 24 Vac input and
, and there is no voltage at the TRIAC B output and
common , check the wiring between the UC400 24Vac transformer supply terminals and
the TRIAC supply terminals.
– Check damper actuator motor by applying 24 Vac directly to com
mon (blue) and jumper
open (black) wire to ground to drive damper open. Damper should drive open. If not, replace
damper actuator.
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