CNT-SVX07D-EN
51
Troubleshooting
Use
through
to assist you in diagnosing any of the following operational
problems that you might encounter with the Tracer ZN521 zone controller:
•
Fan does not energize (
•
Valves remain closed (Table 18 on page 52)
•
Valves remain open (Table 19 on page 52)
•
Compressors are not running (Table 20 on page 53)
•
Electric heat does not energize (Table 20 on page 53)
•
An outdoor air damper stays closed (Table 21 on page 53)
•
An outdoor air damper stays open (Table 22 on page 54)
Table 17. Fan does not energize
Probable cause
Explanation
Unit wiring
The wiring between the controller outputs and the fan relays and contacts must be pres-
ent and correct for normal fan operation. Refer to applicable wiring diagram.
Failed end device
The fan motor and relay must be checked to ensure proper operation.
Normal operation
The fan will turn off when the controller receives a communicated off signal, when the
fan-speed switch is set to OFF, when specific diagnostics are generated, or when the
default fan speed is set to Off and the fan is operating in the Auto mode. If the controller
is in unoccupied mode, the fan cycles between off and the highest fan speed.
No power to the con-
troller
If the controller does not have power, the unit fan does not operate. For the Tracer ZN521
controller to operate normally, it must have an input voltage of 24 Vac. If the green LED is
off continuously, the controller does not have sufficient power or has failed.
Power-up control-wait
If power-up control-wait is enabled (non-zero time), the controller remains off until one of
two conditions occurs:
1) The controller exits power-up control-wait after it receives communicated information.
2) The controller exits power-up control-wait after the power-up control-wait time expires.
Diagnostic present
Several diagnostics affect fan operation. For information about these diagnostics, see
.
Unit configuration
The controller must be properly configured based on the actual installed end devices and
application. If the unit configuration does not match the actual end device, the fans may
not work correctly.
Manual output test
The controller includes a manual output test sequence you can use to verify output oper-
ation and associated output wiring. However, based on the current step in the test
sequence, the unit fan may not be on. Refer to the
Random start
observed
After power-up, the controller always observes a random start from 5 to 30 seconds. The
controller remains off until the random start time expires.
Cycling fan operation/
continuous
The controller operates the fan continuously when in the occupied, occupied standby, or
occupied bypass mode. When the controller is in the unoccupied mode, the fan is cycled
between high speed and off with capacity.
Unoccupied operation
Even if the controller is configured for continuous fan operation, the fan normally cycles
with capacity during unoccupied mode. While unoccupied, the fan cycles on or off with
heating/cooling to provide varying amounts of heating or cooling to the space.
Fan mode off
If a local fan mode switch determines the fan operation, the off position controls the fan
off.
Requested mode off
You can communicate a desired operating mode (such as off, heat, and cool) to the con-
troller. If off is communicated to the controller, the unit controls the fan off. There is no
heating or cooling.
Summary of Contents for Tracer ZN521
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