Maintenance diagnostics
Translating Multiple Diagnostics
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 failure1
•Entering water temp failure1
•Discharge air temp failure1
•Outdoor air temp failure1
•Local setpoint failure1
•Local fan mode failure1
•CO2 sensor failure1
•Generic AIP failure1
•Humidity input failure1
•Defrosting compressor lockout1
•Maintenance required
•Invalid unit configuration
•Generic temperature failure
•Discharge air low limit
Table
diagnostic | latching? | fan | valves | elec heat | damper |
auxiliary | no | enabled | no action | no action | no action |
temp. failure |
|
|
|
|
|
condensate | yes | off | closed | off | closed |
overflow |
|
|
|
|
|
detection |
|
|
|
|
|
entering | no | enabled | enabled | enabled | enabled |
water temp. |
|
|
|
|
|
failure |
|
|
|
|
|
fan mode | no | enabled | enabled | enabled | enabled |
failure |
|
|
|
|
|
invalid unit | yes | disabled | disabled | disabled | disabled |
configuration |
|
|
|
|
|
failure |
|
|
|
|
|
low temp. | yes | off | open | off | closed |
detection |
|
|
|
|
|
maintenance | yes | enabled | no action | no action | no action |
required |
|
|
|
|
|
setpoint | no | enabled | no action | no action | no action |
zone temp. failure | no | off | closed | off | closed |
Notes:
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.
Latching: A latching diagnostic requires a manual reset of the controller; while a
Enabled: End device is allowed to run if there is a call for it to run.
Disabled: End device is not allowed to run even if there is a call for it to run.
No Action: The diagnostic has no affect on the end device.
1
Resetting Diagnostics
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 device ab le to access the controller’s diagnostic reset input.
6.Tracer ZN520: by cycling the fan switch from Off to any speed setting.
Automatic Reset by the Controller 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
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 After removing and reapplying the 24 VAC power from the board, the unit cycles through a
Using Trane’s Service Tool, Rover™ Rover™, Trane’s service tool, can reset diagnostics present in the controller and troubleshoot the unit. For more information, refer to the Trane publication
Diagnostic Reset
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
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.
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