54
BCXC-SVX01A-EN
Maintenance
Diagnostics
Table M-D-4. Valves Stay Closed
Probable Cause
Explanation
Normal operation
The controller opens and closes the valves to meet the unit capacity require-
ments.
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 the
“Manual Output Test” section.
Diagnostic present
A specific list of diagnostics affects valve operation. For more information,
see the “Diagnostics” section.
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 the “Entering Water Temperature
Sampling” section.
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
If the controller does not have power, the unit fan does not operate. For
controllerthe Tracer
®
ZN010,510 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 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 unit unit wiring diagram
on the unit.
Table M-D-5. Valves Stay Open
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 the
“Manual Output Test” section.
Diagnostic present
A specific list of diagnostics affects valve operation. For more information,
see the “Diagnostics” section.
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
the “Entering Water Temperature Sampling” section.
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 unit wiring diagram on
