Trane Tracer Uc page 66

Troubleshooting
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Wrong unit size downloaded into the UC400 controller setup screen. Verify that the actual unit
size matches what is listed on the unit nameplate.
Poor inlet configuration.
– Trane recommends 1½-duct diameters of straight duct before the inlet of the box (a 12-inch
box should have 18 inches of straight run duct before the inlet).
To determine whether or not the transducer has failed, check the following:
– Check the 24 volts AC supply at XFMR 24 Vac input and
should be between 20.4 and 27.6 Vac.
– Read the input voltage to the transducer from the UC400 controller between the green and
red wires on P1 of the controller. The voltage should be between 4.50 volts DC and 5.50 volts
DC (5 volts DC cataloged). If voltage not available, replace the UC400 controller.
– Remove the high and low tubes from the transducer (to simulate no flow). Read the
transducer output voltage on P1 of the UC400 controller between the green and the black
wires with a voltmeter. The voltage should be between 0.20 volts DC and 0.30 volts DC (0.25
volts DC is the null voltage output of the transducer indicating zero flow). If voltage not
available, replace the transducer.
Note: The formula for the transducer output voltage is 0.25 + 0.75 * <delta P>, where
delta P is the pressure in inches of water column. Delta P can range from 0 to 5
inches of W.C.
With flow going across the flow ring, measure the differential pressure with a magnahelic and
use the transducer output voltage formula to check accuracy of reported value. Read the
transducer output voltage between the green and the black wires. The measured value should
correspond to the value given in the transducer output formula. If transducer is off by ± 5%,
replace transducer.
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on the r UC400 controller. Voltage
VAV-SVX07B-EN
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