Psc (Permanent Split Capacitor) Variable Speed Motor Check - Trane Tracer Uc

Troubleshooting
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Equipment Damage!
The UC400 controller outputs are switched to ground. Do not jumper 24 Vac to binary output
TRIAC(s) because damage will occur.
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PSC (Permanent Split Capacitor) Variable Speed Motor Check

Live Electrical Components!
During installation, testing, servicing and troubleshooting of this product, it may be necessary
to work with live electrical components. Have a qualified licensed electrician or other
individual who has been properly trained in handling live electrical components perform these
tasks. Failure to follow all electrical safety precautions when exposed to live electrical
components could result in death or serious injury.
If the PSC Variable speed motor control does not change the motor speed, check the following:
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– Override damper open until CFM is above enabled flow setpoint fan will cycle OFF .
If the UC400 controller is calling for the fan to be ON (viewed in the Status screen), and it is not,
then check the TRIAC output wiring and relay output
– Check BO4 to common
on XFMR 24 Vac input and
between 20.4 and 27.6 Vac (24 Vac catalogued). However, voltages at either extreme may
result in system instability.
– TRIACs can be checked by purchasing a 24 Vac LED. Connect LED wires to triac outputs on
controller. Raise setpoint to initiate call for heat. If the UC400 BO LEDs are lit, but the test LED
does not, replace the controller.
Note: Measuring the output voltage with a meter is not a reliable test for TRIAC output
voltage. The TRIAC output requires a small amount of current draw in order to fully
switch 24 Vac to ground. The LED provides the required current draw.
– Remove fan wires from the UC400 controller and apply 24 Vac directly to fan relay wires.
– Fan relay should energize. If it does not energize, check wiring. If the wiring check is good,
replace fan relay.
After all checks have been completed, check motor fan winding integrity and bearing failure.
Wires connected improperly. Refer to the section,
Diagrams, " p. 77.
Check voltage selection switch on side of variable speed motor control. It should be set for
motor voltage.
Check speed control by:
– Turning the voltage selection switch fully counterclockwise.
– Turning the motor speed control potentiometer fully counterclockwise.
– Ensuring the motor remains OFF .
Turn voltage selection switch fully clockwise, but:
– The motor speed control potentiometer still remains fully counterclockwise.
– Measure the motor voltage. It should be no more than 8 Vac lower than line voltage.
. It should have 24 Vac. If it does not, measure the power input to
of the UC400 controller. The supply voltage should be
NOTICE:
WARNING
"Appendix: Typical Trane Factory Wiring
VAV-SVX07B-EN