Installation and Maintenance Manual

Diagnostics
UNT-SVX07D-EN 11 3
Note: The automatic diagnostic reset function does not
operate during the manual output test sequence.
If a special diagnostic occurs within 24 hours after an
automatic diagnostic reset, the controller must be
manually reset. Other possible methods of resetting
diagnostics are described in the sections that follow.
Manual Output Test (Tracer ZN520)
To verify proper end device operation, press the
controller’s Test button. This exercise will verify all outputs
in a predefined sequence, the first of which will attempt to
reset the controller diagnostics if any are present.
Cycling Power to the Controller (Tracer ZN520)
After removing and reapplying the 24 Vac power from the
board, the unit cycles through a power-up sequence. By
default, the controller attempts to reset all diagnostics
present at power-up. Diagnostics present at power-up and
those that occur after power-up are handled according to
Tab l e 3 7 .
Using Trane’s Service Tool, Rover (Tracer
ZN520)
Rover, Trane’s service tool, can reset diagnostics present in
the controller and troubleshoot the unit. For more
information, refer to the Trane publication EMTX-SVX01G-
EN (Rover Service Tool: Installation, Operation, and
Programming Guide).
Diagnostic Reset (Tracer ZN520)
Any device that can communicate the network variable
nviRequest (enumeration “clear_alarm”) can reset
diagnostics in the Tracer ZN520 controller.The controller
also attempts to reset diagnostics whenever power is
cycled.
Cycling the Fan Switch (Tracer ZN520)
Cycle the fan speed switch from Off to any speed and the
controller resets all diagnostics. Diagnostics may recur
immediately if the problem still exists.
Table 37. Tracer ZN510 controller diagnostics
Diagnostic Latching? Fan Valves
Elec
Heat Damper
Auxiliary temp.
failure
No
Enable
d
No
action
No action No action
Condensate overflow
detection
Yes Off Closed Off Closed
Entering water temp.
failure
No
Enable
d
Enabled Enabled Enabled
Fan mode failure No
Enable
d
Enabled Enabled Enabled
Invalid unit
configuration failure
Yes
Disable
d
Disabled Disabled Disabled
Low temp. detection Yes Off Open Off Closed
Maintenance
required
Yes
Enable
d
No
action
No action No action
Setpoint No
Enable
d
No
action
No action No action
Zone temp. failure No Off Closed Off Closed
Notes:
1. Priority Level: Diagnostics are listed in order from highest to lowest
priority. The controller senses and records each diagnostic
independently of other diagnostics. It is possible to have multiple
diagnostics present simultaneously. The diagnostics affect unit
operation according to priority level.
2. Latching: A latching diagnostic requires a manual reset of the
controller; while a non-latching diagnostic automatically resets when
the input is present and valid.
3. Enabled: End device is allowed to run if there is a call for it to run.
4. Disabled: End device is not allowed to run even if there is a call for it
to run.
5. No Action: The diagnostic has no affect on the end device.
Table 38. Fan outputs do not energize (Tracer ZN520)
Probable
Cause Explanation
Random start After power-up, the controller always observes a random
start that varies observed between 0 and 25 seconds. The
controller remains off until the random start time expires.
Power-up
control wait
When power-up control wait is enabled (non-zero time), the
controller remains off until one of two conditions occurs:
1. The controller exits power-up control wait once it receives
communicated information.
2. The controller exits power-up control wait once the
power-up control wait time expires.
Cycling fan
operation
When the fan mode switch is in the auto position, the unit
fan cycles off when there is no call for heating or cooling. The
heating/cooling sources cycle on or off periodically with the
unit fan to match the capacity according to pulse-width-
modulation (PWM) logic.
Unoccupied
operation
The fan cycles with capacity when the unit is in unoccupied
mode. This occurs even if the unit is in continuous fan
operation. While unoccupied, the fan cycles on or off with
heating/cooling to provide varying amounts of heating or
cooling to the space to match the to pulse-width-modulation
(PWM) logic.
Fan mode off When using the local fan mode switch to determine the fan
operation, the off position controls the unit fan to off.
Requested
mode: off
It is possible to communicate the operating mode (such as
off, heat, and cool) to the controller. When “off” is
communicated to the controller, the unit controls the fan to
off. The unit is not capable of heating or cooling when the
controller is in this mode.
Diagnostic
present
A specific list of diagnostics effects fan operation. For more
information, see “Diagnostics,” p. 112.
No power to
the controller
If the controller does not have power, the unit fan will not
operate. For the controller to operate normally, it must have
an input voltage of 24 Vac. When the green LED is off
continuously, the controller does not have sufficient power
or the controller has failed.
Manual output
test
The controller includes a manual output test sequence to
verify binary output operation and the associated wiring.
However, based on the current step in the test sequence, the
unit fan may not be powered on. Refer to “Manual Output
Test (Tracer ZN520),” p. 113.
Unit wiring The wiring between the controller outputs and the fan relays
and contacts must be present and correct for normal fan
operation. Refer to the typical unit wiring diagrams (see
“Wiring Diagrams,” p. 133).
UNT-SVX07_-EN.book Page 113 Friday, April 27, 2012 9:40 AM