Installation and Maintenance Manual

Diagnostics
90 UV-SVN02C-EN
Translating Multiple Diagnostics (Tracer
ZN520)
The controller senses and records each diagnostic
independently of other diagnostics. It is possible to have
multiple diagnostics present simultaneously. The
diagnostics are reported in the order they occur.
Possible diagnostics include:
• Low temperature detection
• Condensate overflow
• Low air flow—fan status
• Discharge air temp limit
• Space temperature failure
1
• Entering water temp failure
1
• Discharge air temp failure
1
• Outdoor air temp failure
1
• Local setpoint failure
1
• Local fan mode failure
1
•CO
2
sensor failure
1
• Generic AIP failure
1
• Humidity input failure
1
• Defrosting compressor lockout
1
• Maintenance required
• Invalid unit configuration
• Generic temperature failure
• Discharge air low limit
Resetting Diagnostics (Tracer ZN520)
There are a number of ways in which diagnostics are reset:
1. Automatic reset by the controller
2. By initiating a manual output test at the controller
3. By cycling power to the controller
4. Through Rover, Trane’s service tool
5. Tracer ZN520: by using any other communicating
devic
e ab le to access the controller’s diagnostic reset
input.
6. Tracer ZN520: by cycling the fan switch from Off to any
speed set
ting.
Automatic Reset by the Controller (Tracer
ZN520)
The controller includes an automatic diagnostic reset
function that attempts to automatically restore the unit
when a low temperature diagnostic occurs.
Note: The controller implements the automatic
diagnostic reset function only once every 24 hours.
For the controller to increment the 24 hour timer,
you must maintain power to the controller. Cycling
power resets all timers and counters.
After the controller detects the first special diagnostic, the
unit waits 30 minutes before invoking the automatic
diagnostic reset function. The automatic diagnostic reset
function clears the special diagnostic and attempts to
restore the controller to normal operation. The controller
resumes normal operation until another diagnostic
occurs.
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
Table 30.
1
Non-latching diagnostics automatically reset when the input is present and valid.
Table 30. Tracer ZN520 controller diagnostics
Diagnostic Latching Fan Valves
Elec
Heat Damper
Auxiliary temp.
failure
No Enabled
No
action
No action No action
Condensate overflow
detection
Yes Off Closed Off Closed
Entering water temp.
failure
No Enabled Enabled Enabled Enabled
Fan mode failure No Enabled Enabled Enabled Enabled
Invalid unit
configuration failure
Yes Disabled Disabled Disabled Disabled
Low temp. detection Yes Off Open Off Closed
Maintenance
required
Yes Enabled
No
action
No action No action
Setpoint No Enabled
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.
UV-SVN02_-EN.book Page 90 Thursday, January 24, 2013 4:48 PM