Tracer, Zn.520 – Trane LO User Manual
Page 80
Tracer
®
ZN.520
80
UNT-IOM-6
Note 3: When the outdoor air temperature sensor has failed or is not
present, the Tracer
®
ZN.520 controller generates a diagnostic to
indicate the sensor loss condition. The controller automatically clears
the diagnostic once a valid outdoor air temperature value is present
(non-latching diagnostic). When the outdoor air temperature sensor
fails or is not present, the controller prohibits economizer operation.
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
CO2 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
1
Non-latching diagnostics automatically reset when the input is
present and valid.
There are six ways to reset unit diagnostics:
Automatically by the controller
By initiating a manual output test at the controller
By cycling power to the controller
By using a building automation system
By using the Rover service tool
By using any other communicating device able to access the
controllers diagnositc reset input
By cycling the fan switch from off to any speed setting
Automatically: The Tracer
®
ZN.520 controller includes an automatic
diagnostic reset function.This function attempts to automatically
recover a unit when the Low Temperature Detection diagnostic
occurs.When this diagnostic occurs, the controller responds as
defined in the Diagnostics table in the previous Summary section.
After the controller detects the Low Temperature Detection diagnos-
tic, the unit waits 30 minutes before invoking the automatic diagnostic
reset function.The automatic diagnostic reset function clears the Low
Temperature Detection diagnostic and attempts to restore the control-
ler to normal operation.The controller resumes normal operation until
another diagnostic occurs.
Translating Multiple
Diagnostics
Resetting
Diagnostics