Installation and Maintenance Manual

76 VAV-SVX07A-EN
Troubleshooting
• Tracer™ TU service tool will indicate that calibration is taking place by a calibration percent
complete indicator.
• When calibration is complete, the box will release to auto. Drive the box open to make sure
that the box is not below 5% of its cataloged CFM. The controller is accurate in reading flow
from 5% to 110% of cataloged CFM.
• Release the box to auto and perform any necessary balancing work. See Tracer TU Help for
balancing details.
• Check to see if flow has been established, If flow not established or inaccurate proceed to
Step 2.
2. The tubing or flow ring is off, reversed, plugged, or has a leak.
• Check with a magnehelic gauge and compare with the delta pressure (DP) chart located on
the VAV box.
• Check the tubing for reversal and/or leaks.
• Check the flow ring for plugged holes. Blow out with compressed air if necessary.
3. Wrong unit size downloaded into the Tracer UC400 controller setup screen. (See programming
section for menu details.)
• Verify that the actual unit size matches the unit's nameplate.
4. 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).
5. To determine whether or not the transducer has failed, perform the following steps:
• Check the 24 volts AC supply at XFMR 24 VAC input and on the Tracer UC400 controller.
Voltage should be between 20 volts AC and 28 volts AC.
• Read the input voltage to the transducer from the Tracer™ UC400 controller between the
green and red wires on P1 of the Tracer UC400 controller. The voltage should be between
Figure 35. Sensor signal vs. airflow delivery
0.01
0.1
1
5
10 100 1,000 10,000
Cfm
Flow Sensor DP (In . w g )
4"
12"10"8"6"
5"
14"16"