Installation and Maintenance Manual

11 2 UNT-SVX07D-EN
Diagnostics
Output Testing and Diagnostics
(Tracer ZN520)
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 an
y 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 (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.
Table 36. Tracer ZN520 diagnostics
Diagnostic Fan Other Outputs
(a)
(a)The generic binary output (TB4-1, TB4-2) state is unaffected by all unit
diagnostics.
Condensate
overflow
Off Valves Closed, Fresh air damper Closed, Electric
heat Off, Baseboard heat Off
Low temperature
detection
Off Valves Open, Fresh air damper Closed, Electric heat
Off, Baseboard heat Off
Low air flow - fan
failure
Off Valves Closed, Fresh air damper Closed, Electric
heat Off, Baseboard heat Off
Space
temperature
failure
Off Valves Closed, Fresh air damper Closed, Electric
heat Off, Baseboard heat Off
Entering water
temp failure
On Valves Enabled
(b)
, Fresh air damper Enabled
(b)
,
Electric heat Enabled
(b)
, Baseboard heat Off
(b)When the entering water temperature is required but not present, the
Tracer ZN520 controller generates a diagnostic to indicate the sensor
loss condition. The controller automatically clears the diagnostic once
a valid entering water temperature value is present (non-latching di-
agnostic). When the entering water temperature sensor fails, the con-
troller prohibits all hydronic cooling operation, but allows the delivery
of heat when heating is required. In the Cool mode, all cooling is locked-
out, but normal fan and outdoor air damper operation is permitted.
Discharge air
temp low limit
Off Valves Open, Fresh air damper Closed, Electric heat
Off, Baseboard heat Off
Discharge air
temp failure
Off Valves Closed, Fresh air damper Closed, Electric
heat Off, Baseboard heat Off
Fresh air temp
failure
On Valves Enabled, Fresh air damper Minimum
position
(c)
, Electric heat Enabled, Baseboard heat
Enabled
(c) When the outdoor air temperature sensor has failed or is not present,
the Tracer ZN520 controller generates a diagnostic to indicate the sen-
sor loss condition. The controller automatically clears the diagnostic
once a valid outdoor air temperature value is present (non-latching di-
agnostic). When the outdoor air temperature sensor fails or is not pres-
ent, the controller prohibits economizer operation.
Relative humidity
failure
On Valves Enabled, Fresh air damper Enabled, Electric
heat Enabled, Baseboard heat Enabled
Generic 4–20mA
failure
On Valves Enabled, Fresh air damper Enabled, Electric
heat Enabled, Baseboard heat Enabled
CO
2
Input failure On Valves Enabled, Fresh air damper Enabled, Electric
heat Enabled, Baseboard heat Enabled
Maintenance
required
On Valves Enabled, Fresh air damper Enabled, Electric
heat Enabled, Baseboard heat Enabled
Local fan mode
failure
On Valves Enabled, Fresh air damper Enabled, Electric
heat Enabled, Baseboard heat Enabled
Local setpoint
failure
On Valves Enabled, Fresh air damper Enabled, Electric
heat Enabled, Baseboard heat Enabled
Invalid unit
configuration
Off Valves Disabled, Fresh air damper Disabled,
Electric heat Disabled, Baseboard heat Disabled
Normal—power
up
On Valves Enabled, Fresh air damper Enabled, Electric
heat Enabled
1
Non-latching diagnostics automatically reset when the input is present and valid.
UNT-SVX07_-EN.book Page 112 Friday, April 27, 2012 9:40 AM