Installation and Maintenance Manual

Diagnostics
UNT-SVX07D-EN 127
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 p
lugged in while the ECM
engine is requesting power.
Troubleshooting a motor that does not spin,
or spins too slowly (ECM)
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:
These exceptions are:
1. If a motor has been locked out due to engine locked
rotor protection:
– Assuming Motor 1 has an obstruction. In this case,
the “Status Display” will be interrupted to display:
→→
Solution:
i. Remove obstruction from the fan wheel.
ii. Ensure that motor plugs and all plugs to adapter
boards and the ECM engine board are secure
iii. 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.
iv. Verify that
 and , the low motor
signal output limits, are set correctly.
2. If a motor has been locked
out due to overspeed or
runaway condition:
– Assuming Motor 1 has an o
verspeed condition. In
this case, the “Status Display” will be interrupted to
display:
→→
Solution:
i. Ensure that set-screw is attached firmly to the
motor shaft.
ii. Ensure that motor plugs and all plugs to adapter
boards and the ECM engine board are secure.
iii. Verify that the configuration does not specify a
speed lower than 450 rpm for the affected motor.
Speeds below 450 rpm are not supported on fan-
coil units.
3. VSP Inputs (0–10V inputs) ar
e of the wrong polarity
– Verify that variable speed (VSP)
inputs are properly
wired to 1TB4.
Notes:
• 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 ECM engine board, the customer-supplied
controller or the Tracer ZN controller.
4. Customer Controller output signal to VSP Inputs are
too low
.
Note: If t
he customer supplied controller outputs
signals that are below the noise threshold, they
will be ignored by the ECM Engine.
– The ECM Engine board contains an adjustable
noise floor parameter,
 that can be configured
to reject signals below the noise floor.
– If the noise floor parameter is set too high, it can be
lowered as long as there are acceptable noise levels
on the inputs lines.
Troubleshooting a motor that spins too fast, or
spins without any apparent speed request
(ECM)
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.)
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.
• The new fan coil designs incorporate sophisticated fan
interlocks that will lockout heat if there is a fan failure.
If the preceding conditions do not describe the behavior of
the unit, the following checks should be performed:
UNT-SVX07_-EN.book Page 127 Friday, April 27, 2012 9:40 AM