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3. More than one UCM connected to a
single zone sensor
— Cut jumper wires (W1 and W2) on all
slave units.
In the event that the UCM is not
reading or incorrectly reading the
set point knob, properly inspect
the following:
4. Open circuit or shorted wiring to set
point knob
— Check the resistance across the wires
at the UCM and compare the resistance
to the values shown in Table 8.
5. Zone Sensor set point wheel is disabled
— Enable the zone sensor in the UCM
setup menu.
6. More than one UCM connected to a
single zone sensor
— Cut jumper wires (W1 and W2) on all
slave units.
In the event that the measured
flow reads incorrectly (i.e.
different from the balance report),
properly inspect the following:
1. 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.
2. Wrong unit size downloaded into the
UCM setup menu
— Verify that the actual unit size matches
the unit's nameplate.
3. 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).
4. UCM going through a recalibrate
— Check the recalibrate override and wait
for the unit to finish the calibration.
5. Measured flow reading from flow hood
differs from UCM's flow reading
— After verifying that none of the above
conditions exist, follow the steps for
calibration listed under the Air Valve
Reading Position Instead of Flow
section. If a discrepancy between the
flow hood CFM and the UCM CFM still
VAV-SVX01B-EN
Trouble
Analysis
exists, change the flow calibration
factor by entering the actual CFM as the
"Measured Cooling Flow" in the UCM
setup menu.
In the event that the fan and/or
heat outputs are not energizing,
properly inspect the following:
1. UCM downloaded incorrectly
— Check fan and heat type parameter.
2. Minimum heating CFM is not being
met, airflow is too low
— Increase the airflow or lower the
minimum heating flow.
3. Fan/Heat relays have failed
— Remove fan/heat wires from UCM and
apply 24 VAC directly.
Note: UCM Outputs are switched to
ground. Do not jumper 24 VAC to J9, J10,
or J11 because damage will occur.
4. Tracer Summit has the fan/heat outputs
disabled
— Check group, global, and/or Tracer
overrides.
5. A flow override exists locking out the
fan/heat outputs
— Check group, global, and/or Tracer
overrides.
6. Outputs on the UCM are configured as
normally closed
— Verify the output configuration in the
UCM setup menu.
7 . Zone temperature is at or above the
heating set point
— Increase the UCM heating set point.
In the event that the air valve is
not modulating, properly inspect
the following:
1. Tracer Summit or UCM has
enabled an override function
— The overrides are Open, Closed, Min, or
Max. Disable all overrides.
2. UCM is going through a recalibrate
(reset) command
— Wait for calibration to finish.
3. Air valve motor has failed
— Check motor by applying 24 VAC
directly to common (blue) and open
(black)/close (red) wires.
Note: UCM Outputs are switched to
ground. Do not jumper 24 VAC to J1-3 or
J1-4 because damage will occur.
4. Zone temperature is greater than the
heat set point or less than the cool set
point
— Change the heat and/or cool set points.
In the event that the air valve is
reading position instead of flow,
properly inspect the following:
1. Airflow is below 5% or above 110%
cataloged
— The UCM reverts to pressure
dependent mode (position control) and
position is displayed rather than CFM.
2. Unit type is not VariTrane nor Generic
— Change the unit type to VariTrane or
Generic.
3. Transducer has failed
— Pressure transducers are responsible
for reading the airflow across the flow
ring and converting it to an electronic
signal. This signal is sent back to the
UCM board and flow is read at the
UCM status and setup screens. When a
pressure transducer fails, the air valve
will assume pressure dependent
operation and reverts to position
control. To determine whether or not the
transducer has failed, perform the
following steps:
A.Check the 24 volts AC supply at TB1 on
the UCM board. Voltage should be
between 20 volts AC and 28 volts AC.
B.Read the input voltage to the
transducer from the UCM controller
between the green and red wires on J3
of the UCM board. The voltage should
be between 4.50 volts DC and 5.50 volts
DC (5 volts DC cataloged).
C.Remove the high and low tubes from
the transducer (to simulate no flow).
Read the transducer output voltage on
J3 of the UCM board 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).
D.Replace the tubes on the transducer.
Check the transducer tubes and the
flow ring to make sure that they are
positioned correctly and properly
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