Diagnostics and Troubleshooting
86
UNT-SVX041D-EN
Replacing ECM Components
Replacement Guidelines
•
ECM motors contain capacitors which store residual
energy. Please keep clear of the fan wheels for
five minutes after the power has been removed from
the system, as a power request with the motor
powered off, could result in a very short period of
actuation. Unplugging the motor is adequate to ensure
that there will be no power request.
•
Configuration adjustments to the VelociTach motor in
accordance with the parameters that are printed on the
label adjacent to the VelociTach board. These
parameters reflect the factory settings for the unit.
Subsequent changes to parameters made during
commissioning will not be reflected in the printed
parameters.
•
Initial hookups to the CSTI and standard adapter board,
including low voltage interconnections, must be made
with the power off.
•
Do not make connections to the motors or the adapter
boards while power is ON. Do not remove connections
to the motor or the adapter boards while the power is
ON.
•
Caution should be taken to stay clear of hazardous
voltages, moving parts and electric heat elements
while making adjustments to the VelociTach motor
control board. If it is not practical to stay clear of these
areas during adjustment, please contact Trane Global
Parts for configuration kit that allows easy powering of
the engine board outside of the unit with a 9V battery.
•
For safe operation, it is necessary to configure
replacement boards to match the setup/switch
configuration of the previously installed boards.
•
Ensure that new circuit modules are firmly seated on
the nylon standoffs, and that the nylon standoffs are
firmly seated on the metal panel
•
Ensure that drip-loops are maintained on wiring on
pipe end of unit to avoid wicking of water into the unit.
•
Before assuming that any of the boards or components
in the new system have failed, please ensure that the
VelociTach motor control board has been configured
correctly and that the switches on the CSTI board
(where applicable) are set correctly.
•
It is necessary to configure the service replacement
VelociTach motor control board before commissioning
the unit. The board is pre-configured with safe values,
but will NOT work correctly unless properly
configured. The factory shipped parameter settings
are on the label adjacent to the VelociTach.
•
Only genuine Trane replacement components with
identical Trane part numbers should be used.
•
Unit fan assemblies contain concealed wires that
should be removed before the fan-board is removed,
to avoid nicking the wire.
•
Care should be maintained to retain the order of the
motors with respect to the motor plugs. On a unit with
two motors, the double-shafted motor will always be
to the left side, and will be designated as Motor 2 by the
controller.
Table 48. Motor spins too fast or spins without any apparent speed request
Situation
Probable Cause
Motor not controllable
Verify that the voltage jumper on the motor plug harness is absent for 208-230V units and 277V units. If the jumper
is present for these units, the motor electronics will be damaged, and the motor will not be controllable.
Fan speed request too low
Verify that the fan speed request is not below 500 rpm. Speeds below 500 rpm are not supported on the fan coil
product.
Inputs not of consistent
polarity
Verify that the all binary inputs to the customer terminal blocks are of proper and consistent polarity.
• For CSTI units, the fan inputs and end device inputs on TB3 must receive signals that are 24 Vac with respect to the unit
chassis.
Note:
Do not short 24 Vac (pos 1 or pos 2) to chassis; refer to the unit schematic.
Failure of motor control board
Verify that variable speed (VSP) inputs are properly wired to 1TB4.
• Do not short the courtesy 10 VDC supply to chassis or loads that require greater than 10 mA of DC current.
• Please 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.
Output signals being ignored
Verify that the signal on the VSP inputs is noise free. The VelociTach motor control board contains an adjustable noise
floor parameter,
, that can be configured to reject signals below the noise floor.
• If the customer supplied controller outputs signals that are below the noise threshold, they will be ignored by the ECM
engine.
Motor spinning too fast
Verify that VSP input settings are correct. The motor control board contains an adjustable digital amplifier,
,
to compensate for long 10 VDC cable runs. For normalized (0–10 VDC) signals, this setting should be set to 1.000.
If it is set too high, the motors will run faster than the requested ratio, and will hit the limit
before the input
voltage has reached its upper limit.
Motor not controllable
Verify that
and
, the low motor signal output limits, are set correctly.
WARNING
Hazardous Voltage w/Capacitors!
Failure to disconnect power and discharge capacitors
before servicing could result in death or serious injury.
Disconnect all electric power, including remote
disconnects and discharge all motor start/run
capacitors before servicing. Follow proper lockout/
tagout procedures to ensure the power cannot be
inadvertently energized. Verify with a CAT III or IV
voltmeter rated per NFPA 70E that all capacitors have
discharged.
