Trane Tracer Unit Ventilator, ZN.520 manual Questionable unit operation, Troubleshooting, Fans

Troubleshooting

power, the unit cycles through a power-up sequence and clears all timers.

By default, the controller attempts to reset all diagnostics at power- up. Diagnostics present at power- up and those that occur after pow- er-up are handled according to the defined unit diagnostics sequenc- es (For more information see,Table

28:Tracer™ ZN.520 Unit Controller diag- nostics, on page 52 for more information.).

Building automation system

Some building automation sys-

tems (i.e., Tracer Summit building automation system) can reset di- agnostics in the Tracer™ ZN.520 unit controller. For more complete information, refer to the product literature for the building automa- tion system.

Rover service tool

Rover service tool can reset diag- nostics in the Tracer™ ZN.520 unit controller. For more complete in- formation, refer to the Rover In- stallation, Operation, and Programming manual.

Diagnostic reset

Any device that can communicate the network variable nviRequest (enumeration “clear_alarm”) can reset diagnostics in the Tracer™ ZN.520 unit controller. The con- troller also attempts to reset diag- nostics whenever power is cycled.

Cycling the fan switch

If the user cycles the fan speed switch from OFF to any speed, the controller resets all diagnostics. Diagnostics may recur immediate- ly if the problem still exists.

Questionable unit operation

Fans

Table 29: Fan outputs do not energize

Probable cause	Possible Explanation
Unit wiring	The wiring between the controller outputs and the fan relays and contacts must be present and correct
	for normal fan operation.
	If the controller does not have power, the unit fan does not operate. For the Tracer™ ZN.520 Unit
No power to the controller	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 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 devices, the fans may not work correctly.
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.
	When power-up control wait is enabled (non-zero time), the controller remains off until one of two
Power-up control	conditions occurs:
wait	1. The controller exits power-up control wait once it receives communicated information.
	2. The controller exits power-up control wait once the power-up control wait time expires.
Diagnostic present	A specific list of diagnostics affects fan operation. For more information see, Tracer™ ZN.520 Unit
	Controller diagnostics, on page 52 for more information.)
	The controller includes a manual output test sequence you can use to verify output operation and
Manual output test	associated output wiring. However, based on the current step in the test sequence, the unit fan may not
	be on. For more information see, Manual Output Test, on page 48 for more information.)
Fan mode OFF	When a local fan mode switch (provided on the Trane zone sensor) determines the fan operation, the
	off position controls the unit OFF.
Requested mode OFF	You can communicate a desired operating mode (such as OFF, HEAT, and COOL) to the controller. When
	OFF is communicated to the controller, the unit controls the fan OFF. There is no heating or cooling.
UNOCCUPIED operation	When the controller is in the UNOCCUPIED mode, the fan is cycled.
	The controller operates the fan continuously when in the OCCUPIED, OCCUPIED STANDBY, or OCCUPIED
Cycling fan operation/continuous	BYPASS mode. When the controller is in the unoccupied mode, the fan is cycled between HIGH speed and
	OFF with capacity.

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