Installation and Maintenance Manual

Diagnostics
114 UNT-SVX07D-EN
Table 39. Valves stay closed (Tracer ZN520)
Probable
Cause Explanation
Normal
operation
The controller opens and closes the valves to meet the unit
capacity requirements.
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.
Valve override The controller can communicate a valve override request.
This request affects the valve operation.
Manual output
test
The controller includes a manual output test sequence to
verify analog and binary output operation and the associated
wiring. However, based on the current step in the test
sequence, the valves may not be open. Refer to “Manual
Output Test (Tracer ZN520),” p. 113.
Diagnostic
present
A specific list of diagnostics affects valve operation. For more
information, see “Diagnostics,” p. 112.
Sampling
logic
The controller includes entering water temperature
sampling logic that automatically invokes during 2-pipe or
4-pipe changeover. It determines when the entering water
temperature is either too cool or too hot for the desired
heating or cooling mode. Refer to “Entering Water
Temperature Sampling Function (Tracer ZN010 and
ZN510),” p. 89.
Unit
configuration
The controller must be properly configured based on the
actual installed end devices and application. When the unit
configuration does not match the actual end device, the
valves may not work correctly.
No power to
the controller
If the controller does not have power, the valves do 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.
Unit wiring The wiring between the controller outputs and the valve(s)
must be present and correct for normal valve operation.
Refer to the typical unit wiring diagrams (see “Wiring
Diagrams,” p. 133).
Table 40. Valves stay open (Tracer ZN520)
Probable
Cause Explanation
Normal
operation
The controller opens and closes the valves to meet the unit
capacity requirements.
Valve override
The controller can communicate a valve override request to
affect the valve operation.
Manual output
test
The controller includes a manual output test sequence that
verifies analog and binary output operation and the
associated wiring. However, based on the current step in the
test sequence, the valves may be open. Refer to “Manual
Output Test (Tracer ZN520),” p. 113.
Diagnostic
present
A specific list of diagnostics affects valve operation. For more
information, see “Diagnostics,” p. 112.
Sampling
logic
The controller includes entering water temperature
sampling logic that automatically invokes during 2-pipe or
4-pipe changeover to determine if the entering water
temperature is correct for the unit operating mode. Refer to
“Entering Water Temperature Sampling Function (Tracer
ZN010 and ZN510),” p. 89.
Unit
configuration
The controller must be properly configured based on the
actual installed end devices and application. When the unit
configuration does not match the actual end device, the
valves may not work correctly.
Unit wiring
The wiring between the controller outputs and the valve(s)
must be present and correct for normal valve operation.
Refer to the typical unit wiring diagrams (see “Wiring
Diagrams,” p. 133).
Table 41. Electric heat not operating (Tracer ZN520)
Probable
Cause Explanation
Normal
operation
The controller cycles electric heat on and off to meet the
unit capacity requirements.
Requested
mode: off
It is possible to communicate the operating mode (such as
off, heat, cool) to the controller. When off is communicated
to the controller, the units shuts off the electric heat.
Communicated
disable
Numerous communicated requests may disable electric
heat, including an auxiliary heat enable input and the heat/
cool mode input. Depending on the state of the
communicated request, the unit may disable electric heat.
Manual output
test
The controller includes a manual output test sequence that
verifies analog and binary output operation and associated
output wiring. However, based on the current step in the
test sequence, the electric heat may not be on. Refer to
“Manual Output Test (Tracer ZN520),” p. 113.
Diagnostic
present
A specific list of diagnostics affects electric heat operation.
For more information, see “Diagnostics,” p. 112.
Unit
configuration
The controller must be properly configured based on the
actual installed end devices and application. When the unit
configuration does not match the actual end device, the
electric heat may not work properly.
No power to
the controller
If the controller does not have power, electric heat does not
operate. For the controller to operate normally, a 24 Vac
input voltage must be applied. When the green LED is off
continuously, the controller does not have sufficient power
or has failed.
Unit wiring The wiring between the controller outputs and the electric
heat contacts must be present and correct for normal
electric heat operation. Refer to the typical unit wiring
diagrams (see “Wiring Diagrams,” p. 133).
ECM Motor /
Control Board
Failure
ECM controls include sophisticated fan proving / interlock
circuitry that will disable electric heat if one or more motors
are not performing normally
Hot water is
present on a
changeover
unit
On units with changeover coil and electric heat,
simultaneous operation of hydronic heat and electric heat
is not allowed.
Table 42. Fresh air damper stays open (Tracer ZN520)
Probable
Cause Explanation
Normal
operation
The controller opens and closes the fresh air damper based
on the controller’s occupancy mode and fan status.
Normally, the fresh air damper is open during occupied mode
when the fan is running and closed during unoccupied mode.
Manual output
test
The controller includes a manual output test sequence that
verifies analog and binary output operation and associated
output wiring. However, based on the current step in the test
sequence, the fresh air damper may not be open. Refer to
“Manual Output Test (Tracer ZN520),” p. 113.
Unit
configuration
The controller must be properly configured based on the
actual installed end devices and application. When the unit
configuration does not match the actual end device, the
damper may not work correctly.
Unit wiring The wiring between the controller outputs and the fresh air
damper must be present and correct for normal damper
operation. Refer to the typical unit wiring diagrams (see
“Wiring Diagrams,” p. 133).
UNT-SVX07_-EN.book Page 114 Friday, April 27, 2012 9:40 AM