Trane VUV Installation, Operation And Maintenance Manual page 115

Troubleshooting Tips
• VelociTach motor control board configuration must
perfectly match the factory-supplied ECM.
– Refer to "Adjustments," p. 62
motor control board.
• The VelociTach™ motor control board will display
troubleshooting information, and contains dual
tachometers to aid in performance verification.
• Under normal circumstances, the VelociTach display will
display the operational status of the motors and electric
heat circuit/sensors, however, a malfunction will drive a
priority display mode that will present the error code
instantly to the screen. The error must be cleared by
solving by powering down, removing the cause of the
problem and restarting the engine board.
• VelociTach™ label setup document (affixed to the back of
the low voltage access lid) should be used to verify engine
configuration settings.
Table 68. Motor does not spin, spins too slowly
Situation Probable Cause
Motor 1 has an obstruction. "Status Display" will be interrupted to
display:
Motor has been locked out due to
engine locked rotor protection
LOCK Æ Mtr1 Æ LRPT
Motor 1 has an overspeed condition. The "Status Display" will be
interrupted to display:
Motor has been locked out due to
overspeed or runaway condition
Ospd
VSP Inputs (0–10V inputs) are of
Variable speed (VSP) inputs may not be properly wired to 1TB4
the wrong polarity
Customer Controller output signal
to VSP Inputs are too low.
Note: If the customer supplied
Noise floor is set too high.
controller outputs signals
that are below the noise
threshold, they will be
ignored by the ECM Engine.
Typical equipment and controls design practice will ensure that
the fans will come on if there is a call for heat, cool, or
ventilation. In most cases, we will depend on the controller/
thermostat to call for the fan to come on when appropriate, but
during calls for electric heat, or calls for heat on CSTI units
equipped with electric heat, as a call for the appropriate fan
speed. This behavior, as described previously, is an indirect
request.
When a call for electric heat is made, the system will positively
drive the fan on to the correct speed, regardless of whether the
controller has asked for fan operation or not. The unit design
incorporates an interlock instead of a lock-out. (It does not lock
out electric heat if the fan is set to off; it brings the fan on.)
UV-SVX005G-EN
for configuration of the
→ →
Mtr1 Ospd
Diagnostics and Troubleshooting
• For proper operation of the system, all plugs must be firmly
seated in all boards and motors. Insecure connections will
cause malfunction and the system will shutdown.
• Do not unplug or plug-in motors or connectors while the
system is receiving a speed request of any kind. The
system must be powered down before plugging or un-
plugging connections to the adapter boards, engine
boards or motors. Failure do so will register diagnostics or
cause unsafe operation and reduction in the contact life of
the connectors.
• The motor will not spin if plugged in while the ECM engine
is requesting power.
Motor
The motor connections and motor plug connections to the
adapter boards should be secure. Unit should be powered off
to check the fit of the connectors.
When configured correctly, the system will always respond
positively to direct, indirect, and conflicting speed requests
with very few exceptions.
Solution
• Remove obstruction from the fan wheel.
• Ensure that motor plugs and all plugs to adapter boards and the ECM
engine board are secure
• Verify that the configuration does not specify a motor that is
physically missing. Most units require only one motor. The controller
is made aware of the missing motor by specifying all speeds related
to Motor 2 to 0 rpm.
M1Lo
• Verify that
are set correctly.
• Ensure that set-screw is attached firmly to the motor shaft.
• Ensure that motor plugs and all plugs to adapter boards and the ECM
engine board are secure.
• Verify that the configuration does not specify a speed lower than
450 rpm for the affected motor.
• Do not short the courtesy 10 Vdc supply to chassis or loads that
require greater than 10 mA of DC current.
• Observe proper polarity of 0–10 Vdc inputs. Failure to observe
proper polarity can cause failure of the VelociTach™ motor control
board, the customer-supplied controller, or the Tracer® ZN
controller.
• The VelociTach™ motor control board contains an adjustable noise
vflr
floor parameter,
below the noise floor.
• The noise floor parameter is set too high, it can be lowered as long
as there are acceptable noise levels on the inputs lines.
Notes: In many cases, indirect requests will result in fan
behavior change regardless of whether the end-
device fails to actuate (due to device failure, or
safety/down-stream lockouts). If there is hot water
available on CSTI units with changeover coils and
electric heat, we will still drive the fan to the
appropriate electric heat speed.
If the preceding conditions do not describe the behavior of the
unit, the following checks should be performed:
M2Lo
and , the low motor signal output limits,
that can be configured to reject signals
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